Article

Polyacrylamide Review: Soil Conditioning and Environmental Fate

If you want to read the PDF, try requesting it from the authors.

Abstract

The adoption of polyacrylamide (PAM) in reducing irrigation‐induced erosion in California's San Joaquin Valley has been stymied by the lack of information about its toxicity and environmental fate. A review of the literature was conducted to bring to the forefront knowledge of polyacrylamide, its effectiveness in controlling erosion and its environmental fate. Polyacrylamide is a water‐soluble, high molecular weight synthetic organic polymer that primarily interacts with the clay fraction of soils. The degree of interaction depends on both the properties of the polymer and properties of the soil. It is effective in stabilizing soil aggregates, reducing soil erosion, and increasing water infiltration, and also has an indirect significant impact upon crop growth and yield. For the most part, polyacrylamide is resistant to microbial attack, and its degradation is mainly through physical breakdown. Polyacrylamide has been shown to be non‐toxic to humans, animals, fish, and plants; the only concern has been the toxicity of its residual monomer (acrylamide) content, which is a known neurotoxin to humans. The residual monomer is bio‐degradable and does not accumulate in soils. The major source of acrylamide that is released into the environment if from the use of polyacrylamide products, so the FDA regulates the residual monomer content of PAM used in food contact products. If the acrylamide content is kept to a minimum, PAM itself does not pose any environmental threat, and thus, can be used effectively as a soil conditioner.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the author.

... Polyacrylamide can be manufactured to have long-chain lengths and a high molecular weight. Furthermore, it is a water-soluble synthetic polymer (Seybold 1994). The two polymers that were added to the bentonite-sand mixtures were an anionic and a cationic polyacrylamide, respectively. ...
... When polyacrylamide is mixed with soil composed of silty loam or sandy loam, it causes an increase in stability and a decrease in soil erosion. By binding soil particles together, a polyacrylamide acts as a reinforcement agent that stabilizes soil and lowers erosion potential during the construction of a structure (Seybold 1994). ...
... Polyacrylamide is a water-soluble polymer which has a high binding capacity when it comes into contact with water and clay particles (Seybold 1994). Due to the increase in the polyacrylamide content in bentonite-sand mixtures, the rate of the water absorption onto the polymer chains increases and hydrogel products are formed. ...
Article
Full-text available
Bentonite-sand mixtures are typically used in engineering applications such as cutoff walls for waste containment facilities or barriers in landfills and freshwater reservoirs. However, low or reduced mechanical and hydraulic performance of a bentonite-sand mixture might result in the failure of the engineering structure. In order to enhance the mechanical and hydraulic properties of a bentonite-sand mixture, an anionic and a cationic polyacrylamides with a content of 1, 2, 5, 10, and 15% respectively were added to the bentonite-sand mixtures. The polyacrylamides used in this study were water-soluble synthetic polymers with high molecular weights. They had enhanced flocculation capability when coming into contact with soil and water. Standard Proctor compaction, consolidated-drained direct shear, unconfined compression, falling-head permeability, and free swell tests were performed on the bentonite-sand mixtures that had different bentonite contents. Test results indicated that cohesion, unconfined compressive strength, maximum dry unit weight, and swell index increased while internal frictional angle, permeability, and optimum water content decreased as a result of the polyacrylamide addition. The rate of change was much higher when the polyacrylamide content was increased up to 2%. The performance of the anionic polyacrylamide was found to be slightly better than that of the cationic polyacrylamide in terms of both strength and permeability. In conclusion, 2% anionic polyacrylamide addition resulted in a sufficient increase in the shear and compressive strength, a slight increase in the swell index, and a sufficient decrease in the permeability of the bentonite-sand mixtures.
... It was supplied in granular form and was diluted with water for application (see Figure A1 of the Appendix A section). PAMs are a group of hydrophilic, miscible synthetic polymers formed by the polymerization of acrylamide (AMD) and related monomers (CH 2 =CHC(O)NH 2 ); they can be synthesized in non-ionic, cationic or anionic forms [51]. The anionic variant, as used in the present study, can be developed through two common pathways: (i) hydrolysis of non-ionic PAM with a strong base such as sodium hydroxide (NaOH), as demonstrated in Figure 2a; and (ii) copolymerization of AMD and acrylic acid or a salt of acrylic acid (e.g., sodium acrylate), as illustrated in Figure 2b [52]. ...
... It was supplied in granular form and was diluted with water for application (see Figure A1 of the Appendix A section). PAMs are a group of hydrophilic, miscible synthetic polymers formed by the polymerization of acrylamide (AMD) and related monomers (CH2=CHC(O)NH2); they can be synthesized in non-ionic, cationic or anionic forms [51]. The anionic variant, as used in the present study, can be developed through two common pathways: (i) hydrolysis of non-ionic PAM with a strong base such as sodium hydroxide (NaOH), as demonstrated in Figure 2a; and (ii) copolymerization of AMD and acrylic acid or a salt of acrylic acid (e.g., sodium acrylate), as illustrated in Figure 2b [52]. ...
... The anionic variant, as used in the present study, can be developed through two common pathways: (i) hydrolysis of non-ionic PAM with a strong base such as sodium hydroxide (NaOH), as demonstrated in Figure 2a; and (ii) copolymerization of AMD and acrylic acid or a salt of acrylic acid (e.g., sodium acrylate), as illustrated in Figure 2b [52]. Anionic PAMs are mainly employed to encourage flocculation of aqueous suspensions [51,53,54]. Other common applications, as reported in the literature, include their widespread use in the mining industry for thickening and dewatering of concentrates and tailings, as well as their successful adoption in routine construction practices, such as soil compaction, and for erosion control [52,55,56]. ...
Article
Full-text available
This study investigates the combined performance of ground rubber (GR), the additive, and polyacrylamide (PAM), the binder, as a sustainable solution towards ameliorating the inferior geotechnical attributes of an expansive clay. The first phase of the experimental program examined the effects of PAM concentration on the soil’s mechanical properties—consistency, sediment volume attributes, compactability, unconfined compressive strength (UCS), reactivity and microstructure features. The second phase investigated the effects of GR content, with and without the optimum PAM concentration. An increase in PAM beyond 0.2 g/L, the identified optimum concentration, caused the excess PAM to act as a lubricant rather than a flocculant. This feature facilitated reduced overall resistance to sliding of soil particles relative to each other, thereby adversely influencing the improvement in stress–strain–strength response achieved for ≤0.2 g/L PAM. This transitional mechanism was further verified by the consistency limits and sediment volume properties, both of which exhibited only minor variations beyond 0.2 g/L PAM. The greater the GR content, the higher the mobilized UCS up to 10% GR, beyond which the dominant GR-to-GR interaction (i.e., rubber-clustering) adversely influenced the stress–strain–strength response. Reduction in the soil’s swell–shrink capacity, however, was consistently in favor of higher GR contents. Addition of PAM to the GR-blended samples amended the soil aggregate–GR connection interface, thereby achieving further improvements in the soil’s UCS and volume change behaviors. A maximum GR content of 20%, paired with 0.2 g/L PAM, managed to satisfy a major decrease in the swell–shrink capacity while improving the strength-related features, and thus was deemed as the optimum choice.
... Acrylamide is an ideal material for the synthesis of cross-linked hydrogel particles for use in environmental technologies. These hydrogels exhibit a high water retaining capacity (greater than 90% of their wet mass), good mechanical strength and resistance to microbial attack (Seybold, 1994). Their degradation is very slow (about 10% per year) and occurs mainly through physical breakdown (Barvenik, 1994;Seybold, 1994). ...
... These hydrogels exhibit a high water retaining capacity (greater than 90% of their wet mass), good mechanical strength and resistance to microbial attack (Seybold, 1994). Their degradation is very slow (about 10% per year) and occurs mainly through physical breakdown (Barvenik, 1994;Seybold, 1994). In addition, these polymers have been shown to pose no environmental threat, (although a lack of inhibitory effects on soil organisms through indirect means or degradation products has not been definitively demonstrated) and their synthesis is relatively cheap so they could be used for large-scale in situ remediation of contaminated soils (Seybold, 1994). ...
... Their degradation is very slow (about 10% per year) and occurs mainly through physical breakdown (Barvenik, 1994;Seybold, 1994). In addition, these polymers have been shown to pose no environmental threat, (although a lack of inhibitory effects on soil organisms through indirect means or degradation products has not been definitively demonstrated) and their synthesis is relatively cheap so they could be used for large-scale in situ remediation of contaminated soils (Seybold, 1994). ...
... Since then, research on polymer-soil interaction has transcended into engineering and agricultural applications [7]. Natural polymers including polysaccharides and synthetic polymers such as polyacrylamides have exhibited promising benefits in agricultural applications by enhancing soil aggregate stability and conserving water in addition to reducing the effects of water and wind erosion as well as harmful vegetation growth [8]. In contrast, the application of polymers in engineering has often been constrained due to their high cost and thereby has been overshadowed by the use of traditional stabilizers, mainly Portland cement and lime. ...
... Biopolymers like polysaccharides occur naturally and have been widely used in food industry [14]. Synthetic polymers such as polyacrylamide have been used in irrigation for agricultural purposes for decades [8]. These polymers are proven to be environmentally friendly and boost the enthusiasm of designers and contractors to explore their uses in soil stabilization. ...
... They were later deployed for uses beyond agriculture control, including construction site erosion, use in storm water runoff ponds to accelerate water clarification, soil stabilization and dust prevention in helicopter-landing zones, and various other high-traffic military situations [7]. It is noteworthy that cationic or nonionic PAMs are often toxic, while anionic PAMs are usually nontoxic to plants, animals and humans [8]. Therefore, most of the PAMs that have been used in soil stabilization are anionic. ...
Article
This paper provides a review of the research on use of polymers for soil stabilization in pavement and geotechnical engineering. First, the properties impacting the effectiveness of widely used polymer classes, including geopolymers, biopolymers, and synthetic organic polymers are discussed. These include types and ratios of the precursor and activator of geopolymers, molecular weight, particle size, charge, conformation, solubility, viscosity, pH, and moisture behavior of organic polymers. Next, the paper reviews the mechanisms governing stabilization of soils with the various polymer classes. The key mechanisms for organic polymer–clay interactions are electrostatic forces and entropy increase, which contribute differently depending on whether the polymer is cationic, neutral, or anionic. On the other hand, the interactions between polymers and coarse-grained soils composed predominantly of sands are mainly attributed to three types of structural changes: a thin film covering sand particles, the formation of polymer ties connecting noncontacted neighboring particles, and the development of adhesion between particles. The mechanism of geopolymer stabilization is through the formation of a sodium and/or calcium aluminosilicate gel, which bind the surrounding soil particles and harden into a denser, stronger matrix. The engineering properties of the soil types after stabilization using polymers, including strength improvement, permeability reduction, swell and shrinkage inhibition, and durability and stability enhancement are discussed. Finally, the paper highlights the challenges for wider use of polymer stabilization of soils including limited evaluation standards, life-cycle cost considerations, and moisture susceptibility. To this end, some future research direction to promote the widespread use of polymers in soil stabilization are recommended including the need for establishment of standard testing protocols, evaluation of in-situ properties of polymer stabilized soils, resolution of durability issues and further in-depth examination of stabilizing mechanisms.
... The pH value of APAM solution at 25℃ 163 is 7.1. APAM does not chemically react with minerals or even microorganisms in the 164 soil and degrades very slowly over time (Seybold 1994;Sojka et al. 2007). APAM is 165 not toxic to humans, but its monomer, i.e., acrylamide, is a neurotoxin that can cause 166 numbness in the lower limbs, weakness in the hands and feet and tenderness in the 167 fingers (Seybold 1994). ...
... APAM does not chemically react with minerals or even microorganisms in the 164 soil and degrades very slowly over time (Seybold 1994;Sojka et al. 2007). APAM is 165 not toxic to humans, but its monomer, i.e., acrylamide, is a neurotoxin that can cause 166 numbness in the lower limbs, weakness in the hands and feet and tenderness in the 167 fingers (Seybold 1994). The residual monomer content of APAM was less than 0.05%, 168 which was within the range of safety (Seybold 1994). ...
... APAM is 165 not toxic to humans, but its monomer, i.e., acrylamide, is a neurotoxin that can cause 166 numbness in the lower limbs, weakness in the hands and feet and tenderness in the 167 fingers (Seybold 1994). The residual monomer content of APAM was less than 0.05%, 168 which was within the range of safety (Seybold 1994). 169 The quicklime ( Fig. 4(b)) had a specific gravity of 1.2-1.3 and a bulk density of 3250-170 3380 kg/m 3 . ...
Article
Full-text available
Marine clays often need improvements before construction and how to stabilize such kind of soft soil has been a great challenge. To address this issue, a newly proposed additive, which is named anionic polyacrylamide (APAM), with lime was applied to the clay stabilization. The main objective of this study is to figure out the effect of APAM on lime-treated marine clay and the micromechanism of stabilization. The unconfined compressive strength (UCS) tests and oedometer tests were performed to investigate the mechanical properties of stabilized clays; the X-ray diffraction (XRD) tests were conducted for mineralogical analysis; the mercury intrusion porosimetry (MIP) tests and scanning electron microscopy (SEM) tests were carried out for microstructural study. The experiment results show that with APAM dosage increasing, the stabilization effect first enhanced and subsequently weakened. The mineralogical analysis reveals that no new compounds were detected as APAM was added. The microstructural study shows that the physical adsorption of APAM to clay particles was conducive to form a more stable clay structure. The Ca²⁺ produced by lime served as the cationic bridge, facilitating the APAM adsorption. However, the electrostatic repulsion between APAM and negatively charged clay particles and the inhibitory effects of APAM on pozzolanic reactions were the main factors weakening the stabilization effect. This study indicates that the APAM/lime treatment method is efficient for marine clay stabilization as long as a rational APAM dosage is selected.
... Among the multitude of commercially manufactured and readily available polymeric stabilizers, polyacrylamide (PAM) seems to possess a variety of favorable soil stabilization attributes and hence demands further attention. PAM refers to a group of synthetic polymers constructed from acrylamide (AMD) monomers (CH2 = CHC(O)NH2); they are hydrophilic (and hence water-soluble) in nature and can be synthesized in anionic, neutral or cationic forms (Seybold, 1994). PAM-based agents have been successfully employed within a variety of industries, including their application as a flocculant in sludge dewatering and water treatment processes, as well as their adoption in the agricultural sector to increase the soil-water retention capacity under drought conditions (e.g. ...
... However, clay-PAM attractions can still be developed through the cationic bridging mechanism, explained as follows. Exchangeable cations present near the clay particle surfaces, particularly divalent cations such as Ca 2+ and Mg 2+ , function as 'attraction bridges' between the negatively charged clay and PAM components (Seybold, 1994;Laird, 1997;Lu et al., 2002;Soltani et al., 2018;Georgees and J o u r n a l P r e -p r o o f Hassan, 2020). This immobilizes the exchangeable cations near the clay surfaces, decreasing the soil's overall cation-exchange capacity and accordingly its volume change potential. ...
Article
Full-text available
This laboratory study examines the potential use of an anionic polyacrylamide (PAM)-based material as an environmentally sustainable additive for the stabilization of an expansive soil from South Australia. The experimental program consisted of consistency limits, sediment volume, compaction and oedometer cyclic swell–shrink tests, performed using distilled water and four different PAM-to-water solutions of PD = 0.1 g/L, 0.2 g/L, 0.4 g/L and 0.6 g/L as the mixing liquids. Overall, the relative swelling and shrinkage strains were found to decrease with increasing number of applied swell–shrink cycles, with an ‘elastic equilibrium’ condition achieved on the conclusion of four cycles. The propensity for swelling/shrinkage potential reduction (for any given cycle) was found to be in favor of increasing the PAM dosage up to PD = 0.2 g/L, beyond which the excess PAM molecules self-associate as aggregates, thereby functioning as a lubricant instead of a flocculant; this critical dosage was termed ‘maximum flocculation dosage’ (MFD). The MFD assertion was discussed and validated using the consistency limits and sediment volume properties, both exhibiting only marginal variations beyond the identified MFD of PD = 0.2 g/L. The accumulated axial strain progressively transitioned from ‘expansive’ for the unamended soil to an ideal ‘neutral’ state at the MFD, while higher dosages demonstrated undesirable ‘contractive’ states.
... The degree of interaction depends on both the properties of the polymer and the properties of the soil. It is effective in stabilizing soil aggregates and increasing water infiltration and also has an indirect significant impact upon crop growth and yield (Seybold, 1994). ...
... This may be due to improving effect of PAM on the soil physical properties (Wallace and Wallace 1986), Fok (1987), Dinel et al (1991), El-Morsy et al (1991), and Bathke et al (1992). Similar finding were obtained by Shainberg et al (1990) andSeybold (1994) who indicated that the PAM treated soils had an increased infiltration rate and also had an indirect significant impact upon crop growth and yield. ...
Thesis
Full-text available
Abstract Soil water movement as influenced by soil properties and irrigation A Field experiments was conducted in Minoufiya University experimental farm, (Egypt) to study soil hydrophysical properties and irrigation on soil water movement and distribution and also to study green pepper response to applied water. Another field experiment was conducted in Hawaii (USA) to study the effect of different irrigation treatments on the amount of deep percolation and onion response to applied water. Six evapotranspiration models were also studied to select the most related model to the actual measured data to determine the irrigation requirements under green house (which are followed to grow vegetable crops in Egypt) conditions. The results could be summarized as follows: Green pepper experiment: drip irrigation more efficient than surface irrigation. The lower irrigation application rate (80% of FC) results better irrigation efficiency and lower consumptive use than the higher one (100% of FC), while the obtained yield was higher for the higher irrigation application rate. PAM application: in general, irrigation efficiency and total yield were increased with PAM application. The PAM application also increased the total amount of deep percolation, while the ratio to the total water application was not affected. The obtained data also indicate that PAM application increased soil infiltration rate and hydraulic conductivity and changes the pore size distribution. Onion experiment: crop yield was increased with increasing applied water up to an optimal point, at this there was no deep percolation in the field, and then the yield decreased one more time and there was some deep percolation. Also it could be concluded that, the pan reading could be directly used as required water for optimal production for Hawaii onion, since it was very close to the actual optimal ET. Penman model was the best model in predicting the pan reading based on the weather data (before calculating the crop coefficient). Hargreaves model give the best fit with the actual data for green pepper and was selected to be employed for irrigation scheduling purpose under green house condition in Egypt.
... The degree of interaction depends on both the properties of the polymer and the properties of the soil. It is effective in stabilizing soil aggregates and increasing water infiltration and also has an indirect significant impact upon crop growth and yield (Seybold, 1994). ...
... This may be due to improving effect of PAM on the soil physical properties (Wallace and Wallace 1986), Fok (1987), Dinel et al (1991), El-Morsy et al (1991), and Bathke et al (1992). Similar finding were obtained by Shainberg et al (1990) andSeybold (1994) who indicated that the PAM treated soils had an increased infiltration rate and also had an indirect significant impact upon crop growth and yield. ...
... Specific gravity 2.73 Consistency limit Liquid limit (%) 36.7 Plastic limit (%) 18.9 Plasticity index 17.8 USCS classification CL Polyurethane and polyacrylamide are used in this study because of their wide application as soil conditioners, enhancing aggregates stability, declining soil erosion, and improving soil mechanical properties [35][36][37]. The polyurethane used herein is prepared by the polymerization of poly-oxypropylene diol (PPG, Jining Hongming Chemical Reagent Co., Ltd., Jining, China), poly-oxyethylene glycol (PEG, Shanghai Ika Biotechnology Co., Ltd., Shanghai, China), and toluene diisocyanate (TDI, Nantong Runfeng Petrochemical Co., Ltd., Nantong, China), and exhibited as a light-yellow transparent emulsion (Figure 1a). ...
... Thermogravimetric analysis for PAM was also carried out with a heating rate of 10 • C/min, a heating range of 0-800 • C, and the results are given in Figure 1d. Polyurethane and polyacrylamide are used in this study because of their wide application as soil conditioners, enhancing aggregates stability, declining soil erosion, and improving soil mechanical properties [35][36][37]. The polyurethane used herein is prepared by the polymerization of polyoxypropylene diol (PPG, Jining Hongming Chemical Reagent Co., Ltd., Jining, China), polyoxyethylene glycol (PEG, Shanghai Ika Biotechnology Co., Ltd., Shanghai, China), and toluene diisocyanate (TDI, Nantong Runfeng Petrochemical Co., Ltd., Nantong, China), and exhibited as a light-yellow transparent emulsion (Figure 1a). ...
Article
Full-text available
There has been a growing interest in polymer applied for soil reinforcement in recent years. However, there little attention has been paid to the effects of polymer on soil cracking behavior, and cracks significantly change soil strength and hydraulic properties and alter reinforcement effectiveness. This study investigated the desiccation cracking behavior of polyurethane (PU) and polyacrylamide (PAM) admixed clayey soils with different polymer concentrations by performing desiccation cracking tests. Scanning electron microscope (SEM) observation was also carried out to obtain the internal structure of these soils. The results show that PU and PAM addition both prolonged the initial evaporation stage, accelerated later evaporation processes, and the effects were related to polymer concentration. Final cracks morphology analyses show that PAM addition slightly reduced the cracking and crushing degree and kept the soil relatively intact, while PU addition slightly enhanced the cracking and crushing degree of soil. In addition, PU and PAM addition both increased the width and length of cracks. The scanning electron microscopy (SEM) analyses show that the effects of polymer on soil evaporation and cracking could be concluded as: (1) storing water in voids, (2) influencing water immigration channel, (3) providing space for soil shrinkage, and (4) enhancing the connection between aggregates, which did not fully come into play because of the existence of hydrogel form. These achievements provide a certain basis for the research of desiccation cracking behavior of polymer treated soil and make significant sense for the safe and effective running of related projects.
... The typical molecular weight for anionic PAM is between 10 and 20 Mg/mol (Green and Stott, 1999;Lu et al., 2002;Sojka et al., 2007;Young et al., 2007). This polymer uses cation-bridging to bond to negatively-charged soil particles suspended in water (Seybold, 1994;Sojka et al., 2007;Theng, 1982). Cations form the bridge between the negatively-charged polymer and negatively-charged particulate that would otherwise repel each other. ...
... LAPAM is a synthetic polymer principally used to treat drinking water, for conditioning potable water sludges, and for sugar processing resulting in high-quality sugar and greater yield. However, inherent environmental and human health risks are still present when applying LAPAM due to unpolymerized acrylamide monomer, a neurotoxin suspected to be a human carcinogen (Seybold, 1994;WHO, 1985;Young et al., 2007). As such, the United States Environmental Protection Agency (EPA) and the Food and Drug Administration (FDA) have set the allowable concentrations for residual acrylamide in LAPAM . ...
Article
A large amount of the water diverted for irrigated agriculture seeps from earthen canals during its conveyance to fields. Besides a shortfall in water availability, a variety of environmental and economic damages are caused by canal seepage. Polymer sealants provide an economical alternative to permanent liners for reducing seepage from earthen canals temporarily. Field studies of the polymer sealant linear anionic polyacrylamide (LAPAM) conducted on two canals in Colorado, USA, and on a canal in Sindh, Pakistan, reveal the potential usefulness of LAPAM to substantially lower seepage losses. LAPAM application rates for the three experiments on the canals in Colorado were 14.2, 18.3, and 12.1 kg per ha of canal wetted perimeter area, and was 12.4 kg/ha for the canal in Pakistan. Flowing water balance tests show a decline of 69-100% in seepage rates for a period of up to three months after LAPAM application. Uncertainty analysis of the pre-and post-application tests on the Colorado canals indicates an 85% likelihood that seepage reduction of some magnitude occurred. Guidelines are presented for conducting further studies of LAPAM and other polymer sealants to systematically determine the impact of several factors that influence seepage control effectiveness.
... High molecular weight polymers based on polyacrylamide (PAM) are used successfully as flocculants [5]. PAMs are non-ionic polymers with amide being the primary functional group (Fig. 1a) which forms the molecules through a polyaddition processes [6]. Industrial PAMs are hydrolyzed and modified to produce a series of acrylic units along the main chain containing carboxylic (Fig. 1b), sulfonic (Fig. 1c), and amine groups (Fig. 1d) which render PAMs weakly to moderately anionic or cationic. ...
Chapter
Full-text available
Flocculants type polyacrylamidePolyacrylamide (PAM) plays an important role in mineral processing circuits. It is common practice to reuse water from the thickening stages to other unit operations such as grinding and flotationFlotation. In the case of molybdeniteMolybdeniteflotationFlotation, an important depressing effect on mineral particles has been demonstrated by the residual flocculant dissolved in the recycled water. The aim of this work was to evaluate the effect of the degradation of a PAM type of flocculant on the flotationFlotation recovery of molybdeniteMolybdenite. The study considered experiments of microflotationMicroflotation, adsorptionAdsorptionisotherms, electrophoretic mobilityElectrophoretic mobility, and intrinsic viscosity measurementsViscosity measurement. Molecular dynamic simulations were used to look for mechanisms of interactions between PAM and molybdeniteMolybdenite. The results showed that molybdeniteMolybdenite recovery was less affected by the flocculant when PAM molecules were subjected to more intense conditions of mechanical shearingShearing. This behavior is related to the adsorptionAdsorption of flocculant on the mineral and the disposition and shape anisotropy of the flocculant chains.
... It delays fertilizer dissolution and increases sorption capacity and nutrient uptake by plants and finally the yield (Jhurry et al., 2001). A favorable soil-water-plant continuum aided by hydrogel has indirect nutritional benefits also, besides providing higher moisture availability for producing better yields (Seybold 1994). The economics thus improves due to higher fertilizer recovery also (Li and Zhang 2010). ...
Article
Full-text available
A field experiment was conducted to study the effect of irrigation scheduling and use of superabsorbent polymers on growth, seed and water productivity, soil moisture dynamics in Indian mustard under semi-arid conditions. During the first year of the study, the increase in the mustard seed yield with irrigations applied at IW/CPE (Irrigation water, mm/Cumulative Pan Evaporation, mm (CPU) ratios 0.8, 0.6, 0.4 and no-irrigation (rainfed) with hydrogel application (þHG) was 18.6, 17.9, 14.4 and 28.3%, respectively, over no hydrogel (-HG). The seed yield enhancement by hydrogel application during the second year varied from 3% under sufficient irrigation to 24.9% under rainfed conditions. The pooled data indicated that the production indices and economics with hydrogel use improved significantly (P 0.05) under limited irrigation or rainfed condition. A net increase of 38, 27.7, and 10.7%, in production efficiency (PE), the net return, and profitability of mustard respectively was observed due to the use of hydrogel improved under the rainfed condition. Under limited irrigation (single irrigation at IW/CPE 0.4), a net increase of 24.2 and 31.8%, in the marginal and gross water productivity of mustard respectively, was recorded with hydrogel use. Similarly, in rainfed conditions, hydrogel increased gross water productivity by 22.6%. The energy intensity under irrigations scheduled at IW/CPE 0.8, 0.6, 0.4, and rainfed condition, was enhanced by 4.9, 5.9, 6.7, and 10.5%, respectively, due to hydrogel application. Thus, the use of hydrogel both under the rainfed condition and deficit irrigation has the potential to enhance productivity, profitability, and bio-energy output of Indian mustard in semi-arid agro-ecologies.
... The main aspects of AP structure that affect biodegradation include the C-C backbone length, the side groups, quaternary carbons, and molecular organization (linear, branched, or cross-linked). Other characteristics such as purity of the product and degree of hydrolysis also influence AP biodegradability assessment (Seybold 1994;Larson et al. 1997;Kay-Shoemake et al. 1998a;Stahl et al. 2000). ...
Article
Full-text available
Acrylic polymers (AP) are a diverse group of materials with broad applications, frequent use, and increasing demand. Some of the most used AP are polyacrylamide, polyacrylic acid, polymethyl methacrylates, and polyacrylonitrile. Although no information for the production of all AP types is published, data for the most used AP is around 9 MT/year, which gives an idea of the amount of waste that can be generated after products’ lifecycles. After its lifecycle ends, the fate of an AP product will depend on its chemical structure, the environmental setting where it was used, and the regulations for plastic waste management existing in the different countries. Even though recycling is the best fate for plastic polymer wastes, few AP can be recycled, and most of them end up in landfills. Because of the pollution crisis the planet is immersed, setting regulations and developing technological strategies for plastic waste management are urgent. In this regard, biotechnological approaches, where microbial activity is involved, could be attractive eco-friendly strategies. This mini-review describes the broad AP diversity, their properties and uses, and the factors affecting their biodegradability, underlining the importance of standardizing biodegradation quantification techniques. We also describe the enzymes and metabolic pathways that microorganisms display to attack AP chemical structure and predict some biochemical reactions that could account for quaternary carbon-containing AP biodegradation. Finally, we analyze strategies to increase AP biodegradability and stress the need for more studies on AP biodegradation and developing stricter legislation for AP use and waste control. Key points • Acrylic polymers (AP) are a diverse and extensively used group of compounds. • The environmental fates and health effects of AP waste are not completely known. • Microorganisms and enzymes involved in AP degradation have been identified. • More biodegradation studies are needed to develop AP biotechnological treatments.
... Polyacrylamides (PAM) are widely used flocculants in the mining industry [3], and Figure 1 shows the chemical structures of anionic (carboxylated and sulfonated), and cationic polyacrylamides. The main functional group in PAM is the amide group (Figure 1d), which form the polymer through a polyaddition process [4]. The ionic character and molecular weight of PAM can be achieved through copolymerization reactions to give them anionic or cationic character. ...
Article
Full-text available
Polyacrylamides (PAM) are used as flocculants in the copper-molybdenum mining industry to improve the settling rate of flotation tailings. These types of reagents are recirculated to flotation in the water that is recovered from the thickeners, and as a result of this practice they can cause depression of flotation of some important minerals such as molybdenite. The objective of this work was to study the effect of a PAM of 11.9% of degree of anionicity on the flotation of molybdenite. The effect of the anionic PAM on molybdenite flotation was studied under different levels (three) of flocculant mechanical shearing. The flotation data was discussed along with intrinsic viscosity, adsorption, induction time, and electrophoretic mobility measurements. It was found that the non-sheared PAM (NS-PAM) had the strongest depressing effect on molybdenite flotation, followed by the moderately sheared PAM (MS-PAM). The depressing effect of the strongly sheared PAM (SS-PAM) was negligible. The flotation data correlated with the induction time measurements that showed that molybdenite became more hydrophilic in the presence of the NS-PAM. The SS-PAM has no effect on the induction times. Further work is ongoing to understand the effect of PAM on molybdenite flotation in the presence of clay minerals and different aqueous media.
... Additionally, APAM previously showed no degradation in BSTs and studies found PAM macromolecules resistant to microbial attack, requiring an initial physical−chemical breakdown. 41,42 Extended test durations in the mBST MR and imBST MR allowed the analysis of lag phases, which extended beyond the standard 28 day test duration. These lag phases, particularly for TEA and 4NP, were often followed by fast and complete degradation of the test chemical (Figure 3a and Supporting Information, Figure S15), indicating the presence of an acclimated viable degrading community. ...
Article
Current biodegradation screening tests are not specifically designed for persistence assessment of chemicals, often show high inter- and intra-test variability, and often give false negative biodegradation results. Based on previous studies and recommendations, an international ring test involving 13 laboratories validated a new test method for marine biodegradation with a focus on improving the reliability of screening to determine the environmental degradation potential of chemicals. The new method incorporated increased bacterial cell concentrations to better represent the microbial diversity a chemical is likely to be exposed to in the sampled environments and ran beyond 60 days, which is the half-life threshold for chemical persistence in the marine environment. The new test provided a more reliable and less variable characterization of the biodegradation behavior of five reference chemicals (sodium benzoate, triethanolamine, 4-nitrophenol, anionic polyacrylamide, pentachlorophenol), with respect to REACH and OSPAR persistence thresholds, than the current OECD 306 test. The proposed new method provides a cost effective screening test for non-persistence that could streamline chemical regulation and reduce the cost and animal welfare implications of further higher tier testing.
... PAM is a water-soluble, organic anionic polymer having a long molecule of identical atom chains held together by covalent bonds [24] that form bridges with the soil particles through cations in soil solution [25]. PAM has proved to be superior to other polymers in controlling erosion [26] and is also used to improve soil physical properties [25]. ...
Article
Full-text available
The use of anionic polyacrylamide (PAM) as a soil conditioner could help prevent soil loss by water. In this study, we determined the effective granular PAM rate that best reduces runoff and soil loss from Oxisols. Furthermore, the effectiveness of the selected PAM rate was tested by applying it in a mixture with gypsum (G) or lime (L). The study was conducted in two phases: (i) Dry PAM rates of 0 (C), 20 kg ha −1 (P20), 40 kg ha −1 (P40), and 60 kg ha −1 (P60) were applied onto soil surface and run for six consecutive rainfall storms of 70 mm h-1 intensity for 1 h duration, and the effective PAM rate was selected; and (ii) G (4 t ha-1) or L (2 t ha-1) were applied alone or mixed with the selected PAM rate. The P20 was found to be effective in reducing runoff in the beginning while P40 and P60 were more effective starting from the third storm through the end of the consecutive storms, but with no statistically significant difference between P40 and P60. Hence, P40 was selected as the most suitable rate for the given test soil and rainfall pattern. On the other hand, the mixed application of P40 with G or L increased infiltration rate (IR) in the first two storms through improving soil solution viscosity. However, effectiveness of the mixtures had diminished by various degrees as rain progressed, as compared to P40 alone, which could be attributed to the rate and properties of G and L. In conclusion, the variation in effectiveness of PAM rates in reducing runoff with storm duration could indicate that the effective rates shall be selected based on the climatic region in that lower rates for the short rains or higher rates for elongated rains. Moreover, combined application of PAM with L could offer a good option to both fairly reduce soil erosion and improve land productivity especially in acidic soils like Oxisols, which requires further field verification.
... PAM is of three types, cationic, non-ionic, and anionic. Cationic absorbed most effectively while anionic is least absorbed, similar is their effectiveness for stabilisation since the negatively charged polymer is repelled by negatively charged clay particle, so polyvalent cation is used as 'cationic bridge' to counterbalance the negative charge of both clay and polymer (Seybold, 1994). Net charge, charge density, and molecular weight must be considered while selecting PAM along with soil properties. ...
Article
Full-text available
Ground improvement will be critically important in the present and future geotechnical practice for designing the structures in weak soil. This paper presents a review of the recent development in ground improvement techniques, especially chemical stabilisers. Various available chemical stabilisers are identified and compared with other available methods. Though the use of chemicals provides an excellent alternative to the traditional methods, they still lack proper understanding regarding their use, handling, application, and long-term effect on the environment. Various chemical stabilisers and their applicability conditions are summarised in the present paper. Insight of biochemical, electrochemical, inorganic, and organic stabilisers is presented with future scope of these methods along with the potential areas where a lot of efforts is needed to industrialise these methods are also discussed briefly. A need for developing a more environmentally friendly and safe method was felt while reviewing these methods. Lack of a large amount of data is a major concern for lesser use of these methods industrially. A lot of laboratory and field experiments should be conducted in different conditions to ensure safe results from chemical stabilisers.
... High to ultrahigh molar mass ( > 1 MDa) anionic polyacrylamides and their analogues are polyelectrolytes which are widely used as flocculent in wastewater treatment [1] , as soil conditioner [2] , as drag reducer [3] , and as viscosity enhancer in Enhanced Oil Recovery for flooding of trapped crude oil from the reservoir [4] . In the oil field application, however, loss of flooding efficiency often arises from shear sensitive chain scissions in porous media and rheological performance deterioration provoked by salinity and high temperature [5,6] . ...
Article
High to ultrahigh molar mass (above 1 million g/mol) anionic poly(acrylic acid-co-acrylamide)s are widely used industrial polymers for water treatment and oil drilling. Their properties are strongly related to their charge density and molar mass distributions. However, due to inherent separation limits of SEC with currently available columns (< 5 ×106 g/mol) and possible occurrence of chain breakage, and/or adsorption leading to abnormal elution, characterization of unusually high molar masses polyelectrolytes is challenging. In this work, we investigate the use of polymer sieving capillary electrophoresis for the size-based characterization of these high to ultrahigh molar mass polyelectrolytes. By optimizing the operating conditions (electric field, ionic strength, injected polyelectrolyte concentration, nature of the polymer sieving), it has been possible to considerably reduce polyelectrolyte aggregation and to get sufficient size-based selectivity, allowing to obtain the size distribution of the polyelectrolytes over a large range of molar mass from 105 up to ~10×106 g/mol. The data processing of the raw electropherograms is a key step in the analytical protocol leading to the molar mass distribution. The polyelectrolyte effective mobility in sieving conditions has to be normalized to its free-draining electrophoretic mobility in free solution conditions to take into account possible variability in the charge density between the different samples.
... comm.). The flocculant is the only chemical that is added in the mining and processing operations, and is not harmful to the environment (Seybold, 1994). The sand tailings from the primary wet plant are returned to the mined-out land and stacked to re-build the dunes in a process called backfilling. ...
... High molecular weight polymers based on polyacrylamide (PAM) are used successfully as flocculants [5]. PAMs are non-ionic polymers with amide being the primary functional group (Fig. 1a) which forms the molecules through a polyaddition processes [6]. Industrial PAMs are hydrolyzed and modified to produce a series of acrylic units along the main chain containing carboxylic (Fig. 1b), sulfonic (Fig. 1c), and amine groups (Fig. 1d) which render PAMs weakly to moderately anionic or cationic. ...
Article
The effect of a carboxylated polyacrylamide (PAM) of 11.9% of degree of anionicity on molybdenite flotation was previously reported. In this work the depressing effect of a polyacrylamide of 8.15% of degree of anionicity (LPAM) on molybdenite flotation under different conditions of mechanical degradation, pH, and concentration is presented. The study of the influence of PAMs anionicity on molybdenite flotation is new and deserved further research. It was found that the non-sheared LPAM had the strongest depressing effect, followed by the moderately sheared LPAM; strongly sheared LPAM did not affect molybdenite flotation. The depressing effect of the LPAM tested in this work on molybdenite flotation and the specific polymer adsorption on the mineral decreased as the pH increased which is opposite to what is observed for more anionic polyacrylamides. These experimental observations suggest that the repulsive forces between the LPAM molecules and the anionic moieties on the molybdenite surfaces outweigh the attractive forces existing between the active polymeric groups and the hydroxylated metal sites on the molybdenite faces. The impact of flocculants in thickening is known, in this work the impact of the anionicity of residual flocculants on the flotation of molybdenite is anticipated.
... Polyacrylamide biodegradation is a complex topic that has been reviewed in the literature [128][129][130][131][132][133][134]. When released into the environment, the polymer molecules will be exposed to various abiotic (i.e., physiochemical degradation) and biotic (i.e., degradation by the action of micro-organisms) conditions that are prone to change the molecule functionality and molecular mass. ...
Article
Full-text available
Humankind is facing a climate and energy crisis which demands global and prompt actions to minimize the negative impacts on the environment and on the lives of millions of people. Among all the disciplines which have an important role to play, chemistry has a chance to rethink the way molecules are made and find innovations to decrease the overall anthropic footprint on the environment. In this paper, we will provide a review of the existing knowledge but also recent advances on the manufacturing and end uses of acrylamide-based polymers following the “green chemistry” concept and 100 years after the revolutionary publication of Staudinger on macromolecules. After a review of raw material sourcing options (fossil derivatives vs. biobased), we will discuss the improvements in monomer manufacturing followed by a second part dealing with polymer manufacturing processes and the paths followed to reduce energy consumption and CO2 emissions. In the following section, we will see how the polyacrylamides help reduce the environmental footprint of end users in various fields such as agriculture or wastewater treatment and discuss in more detail the fate of these molecules in the environment by looking at the existing literature, the regulations in place and the procedures used to assess the overall biodegradability. In the last section, we will review macromolecular engineering principles which could help enhance the degradability of said polymers when they reach the end of their life cycle.
... 4 Hydrogels can prevent erosion when used as a soil conditioner and can deliver protein nutrients to crops in the agricultural industry. 5 Due to the sieving properties of their nanoporous structure, hydrogels are used to purify biologic therapeutics in the pharmaceutical industry. 6 Biodegradable hydrogels are also being explored to be used as enzyme sensors and enzyme-sensitive drug delivery systems. ...
Article
Full-text available
Proteins within nanoporous hydrogels have important biotechnological applications in pharmaceutical purification, tissue engineering, water treatment, biosensors, and medical implants. Yet, oftentimes proteins that are functional in solution lose activity when in contact with soft, nanostructured, condensed phase materials due to perturbations in the folded state, conformation, diffusion, and adsorption dynamics of the protein by the material. Fluorescence microscopy experimentally measures the biophysical dynamics of proteins within hydrogels at the nanoscale and can overcome the limitations of conventional ensemble techniques. An explanation of the benefits of fluorescence is provided, and principles of fluorescence microscope instrumentation and analysis are discussed. Then several nanoscale fluorescence microscopies that image nanoscale protein dynamics within hydrogels are introduced. First, location-based super-resolution imaging resolves the adsorption kinetics of proteins to charged ligands within hydrogels used in pharmaceutical separations. Next, correlation-based super-resolution techniques image the heterogeneity of the nanoscale pore size of the hydrogels and the diffusion of analytes within the pores simultaneously. Finally, fluorescence resonance energy transfer imaging combined with temperature jump perturbations determines the folding and stability of a protein within hydrogels. A common finding with all three fluorescence microscopies is that heterogeneous nanoporous hydrogel materials cause variability of protein behavior dependent on gel sterics and/or interfacial electrostatic forces. Overall, in situ observations of proteins in hydrogels using fluorescence microscopies can inform and inspire soft nanomaterial design to improve the performance, shelf life, and cost of biomaterials.
... PAM is resistant to microbial degradation (Seybold 1994), which may explain its tendency of yielding neutral growth responses. We did detect high levels of K in PAM, but these did not consistently increase with increasing concentrations (exception was in the Bryum sand). ...
Article
Full-text available
Tackifiers are long‐chain carbon compounds used for soil stabilization and hydroseeding and could provide a vehicle for biological soil crust restoration. We examined the sensitivity of two dryland mosses, Bryum argenteum and Syntrichia ruralis, to three common tackifiers ‐ guar, psyllium, and polyacrylamide (PAM) ‐ at 0.5x, 1.0x, and 2.0x of recommended (x) concentrations for erosion control and revegetation. We measured moss shoot, gemma, and protonema production as well as moss organic matter and bound sand masses as indicators of growth and soil holding ability. We tested sand and tackifier chemistry to investigate potential nutrient and toxicant potential on moss growth. Groups of ten fragments from field‐collected mosses were grown on sand in open petri dishes arranged in a growth chamber in replicated blocks containing each tackifier and concentration combination plus a distilled water control. Bryum (n=10) and Syntrichia (n=9) growth were measured at the end of six and five weeks, respectively. Overall model tests yielded statistically significant results (p<0.001) for every variable in each species. When compared to water, guar tended to decrease growth, psyllium tended to increase growth, and PAM's effects were generally neutral to positive. Within tackifier types, increasing concentrations of guar tended to decrease growth, while increasing concentrations of psyllium tended to increase growth. Changes in PAM concentrations had little effect on growth. Increases in guar and psyllium lowered pH and increased P and K. Psyllium and PAM yielded promising results as potential agents of dispersal and adherence of dryland mosses in field restoration. This article is protected by copyright. All rights reserved.
... In our current study, application of DewEco increased the sandy soil's water-holding capacity and the effective soil water content, although the wilting coefficient was also enhanced (Table 4, Figure 4). Although DewEco cannot create a gel in the soil as PAM does, the numerous -COO-groups in DewEco could also contribute to the soil's ability to retain water [16,23,45,46] In addition, application of DewEco significantly increased the soil porosity and enhanced the liquid phase ratio (Figures 2 and 3), each of which is also known to increase water retention. ...
Article
Full-text available
Sandy soil, one of the most abundant soil types in the world, often has lower crop productivity because of poor water and fertilizer retention capacity. The objective of this study was to investigate the effects of the new soil conditioner DewEco (fermented organic material consisted mainly of salt of L-lysine and citric acid) on sandy soil quality and plant growth. Serial dosages of DewEco and nitrogen (N) fertilizer were mixed into sandy soils and planted maize in a greenhouse. DewEco application increased large soil particle composition and decreased small soil particle composition. Soil porosity and the liquid phase increased as the DewEco dosage increased. DewEco also decreased soil pH and increased soil electrical conductivity, soil organic matter content, total nitrogen and available potassium. DewEco significantly enhanced the soil water-holding capacity and soil effective water content although it also increased the wilting coefficient. Finally, DewEco markedly promoted maize growth while improving water use efficiency (WUE) and nitrogen use efficiency (NUE). In addition, there was an interaction effect between DewEco and nitrogen fertilizer, such that the combined effects of DewEco and N exceeded the sum of their respective effects promoting plant growth. Thus, DewEco application can significantly enhance soil water content and nutrient levels by alleviating sandy soil’s physical and chemical properties, thereby promoting plant growth, WUE and NUE. This study indicates that DewEco is a useful eco-friendly sandy soil conditioner for arid and semi-arid regions.
... Choudhary, A.A. Shalaby and A.M. Al Omran 1995; O.A. El-Hady and S.A. Abo-Sedera 2006). PAMs molecules raise flocculation and soil aggregate stability, reducing soil loss, at the same time, the existence of long linear chains of PAM in solution refers to an increase of the solution viscosity ;consequently, an increase in viscosity of the percolating solution can cause a decrease in the IR due to the reduction of the soil hydraulic conductivity (Ajwa, A. Husein and Thomas J. Trout 2006;Young et al., 2009;C.A. Seybold 1994). ...
Article
Full-text available
The field experiment was established in Nineveh nursey located in Mosul governorate, with silty loam texture, during summer season 2019. The study carried out the effect of polyacrylamide (PAMs) and biochar (BC-wheat straw pyrolysis at 400-500c) and the interaction between them on soil hydro-physical properties and productivity of maize crop under drip irrigation. The experiment laid-out in three application level of polyacrylamide (0, 160 and 320 kg ha-1) and biochar (0, 4 and 8 t ha-1) with three replications in a completely randomized block design (RCBD). The result showed polyacrylamide and biochar significantly affect the soil's physical properties (volumetric water content, bulk density, porosity, saturated hydraulic conductivity) and significantly affect plant parameters. The interaction between PAMs and BC showed more efficacy effect compared with control (CK) at (p<0.005). The lowest mean value for Bulk Density was in treatment P 2 B 2 1.077 Mg m-3 compared with CK 1.407 Mg m-3 , total air porosity's highest mean value was in treatment P 2 B 2 59.37% compared with CK 46.92% designate 12.45% increasing carryout significantly effect at level (p<0.005), The saturated hydraulic conductivity effected by PAMs and BC the highest mean value was in treatment P 2 B 2 3.71 cm.hr-1 compared with CK 1.36cm.hr-1. Also the Grain yield affected significantly the highest mean value was in treatment P 2 B 2 10.75 ton ha-1 compared with CK 9 ton ha-1. During the whole summer maize growing season the highest mean value of volumetric water content VWC was in treatment P 2 B 2 45.301% compared with CK 35.058%.
... Therefore, SAPs do not pollute the soil and environment, and they are safe and nontoxic for agriculture application. [141,142] ...
Chapter
Superabsorbent polymer (SAP) material has raised great involvement since sustainable evolution policies tend to extend with the reduced irrigation frequency, overuse of fertilizer, and enhanced water-holding capacity in the soil. These SAPs bring a significant contributing role to agricultural development in the way plant growth. Polysaccharide and polypeptide-based SAPs are produced from a renewable resource or fully synthetic-based SAPs from petroleum resources. In general, biopolymer-based SAPs are degradable by microorganism as well as fully synthetic SAPs. This chapter describes the overview of the semi-synthetic (polysaccharide- and polypeptide-based SAPs) and fully synthetic SAPs that are recently being used in agriculture application as well as various types of evolution in their synthesis process.
Article
Many wetland systems worldwide struggle with high nutrient influx from urban and agricultural inputs that often disturbs ecosystem balance. In the Florida Everglades, concentrations above 15 μg P L⁻¹ have been shown to affect ecosystem balance and have long term effects on downstream periphyton, detritus, soil and macrophyte. Current Stormwater Treatment Areas (STAs) have been shown to effectively lower P levels on average to 41 μg P L⁻¹ (SD of 31 μg P L⁻¹). These levels, released into downstream Water Conservation Areas, exceed a long-term goal of 10 μg L⁻¹ total P targeted for STA outflow concentrations. Here, we look at enhancing P removal through chemical addition to treatment wetland systems through a series of in-situ mesocosm studies informed through laboratory jar tests. In-situ mesocosm results showed Fe and Al metal-based coagulants lowered filtered total phosphorus (FTP) levels but they did not create settleable flocs, thus resulting in no change or even higher unfiltered total phosphorus (UTP) levels when compared to non-dosed control mesocosms. Proprietary cationic polymer blends and anionic polyacrylamide (PAM) added post coagulant dosing were tested to enhance P-removal performance. Cationic polymer addition significantly lowered FTP when combined with Al-based coagulants, suggesting enhanced charge neutralization, and improved UTP removal when combined with Fe-based coagulants, signifying improved bridging or electrostatic patch formation to create larger/denser floc. The addition of PAM after coagulant dosing generally did not improve FTP removal but did improve UTP removal when dosed at levels >0.5 mg L⁻¹. For Fe-based systems, doubling PAM dosage (from 0.5 to 1.0 mg L⁻¹) was slightly more beneficial for UTP removal than doubling coagulant blend dosage. For Al-based systems, doubling coagulant blend dosage was slightly more effective for UTP removal than doubling PAM dosage, but the difference was not significant. The chemical cost savings from utilizing PAMS were large: doubling coagulant blend dose increased chemical costs by $28,000–$100,000 per 1B L of water treated depending upon blend, while doubling PAM dose marginally increased chemical costs by $1700. Wetlands enhanced with chemical addition achieved levels as low as 20–25 μg L⁻¹ UTP and <10 μg L⁻¹ FTP under field conditions. These were lower than average achievable levels by non-dosed mesocosms (84 μg L⁻¹ UTP and 43 μg L⁻¹ FTP). While the goal of 10 μg L⁻¹ total P was not met by these chemically enhanced treatment wetland (CETW) systems, strategic placement to treat water prior to entrance into STAs can potentially help STAs meet this criterion by extending the STAs' effectiveness and lifespan. More importantly, these systems can help mitigate downstream ecosystem imbalance and combat the formation and migration of a moving P front.
Article
Degraded lands resulting from human and natural causes are wide spread in arid and semi‐arid regions throughout the world. Polyacrylamide (PAM) soil amendments are increasingly used to remediate these degraded lands with the potential benefits on soil health and crop production. However, the scientific evidence of farm‐scale use of one‐time vs. repeated application of PAM has not been reported. The specific objective of this research was to determine the effects of single vs. multiple annual PAM application on (i) the dynamic changes in soil quality parameters, and (ii) oat crop productivity indicators in a dryland farming ecosystem. Our data illustrated that multiple years of annual application of PAM significantly increased soil profile water storage, while reduced soil bulk density and electrical conductivity in the top (0‐20 cm) and deeper layers (20‐60 cm) over that for the control or single PAM application. The improved soil micro‐ecological environments led to increased activities of soil enzymes urease (up to 106%), invertase (94%) and catalase (45%). These in turn promoted soil nutrient turnover and availability (e.g. 76% higher soil alkaline N), and crop growth, leading to the improvement in grain protein (up to 31%), protein yield (58%), and partial factor productivity of nitrogen (20%), as compared to the control treatment. Taken together, these soil and crop performance indicators suggest that repeated annual PAM application for a minimum of 2‐3 years would be an effective strategy to combat drought and land degradation and foster sustainable crop production in dryland agriculture under a changing climate scenario.
Thesis
Full-text available
Este trabalho teve como objetivo desenvolver um condicionador de solos a partir da biomassa de Magonia pubescens, uma planta típica do cerrado brasileiro. Foi aplicado a biomassa um tratamento químico oxidativo e posterior secagem. Foi avaliada a composição química do condicionador de solos produzido, as propriedades físico-químicas de capacidade de troca catiônica e capacidade de retenção de água, assim como foram realizados ensaios com aplicação diretamente em dois solos, sendo um com textura arenosa e outro com textura argilosa. Os resultados indicaram que o tratamento químico oxidativo empregado permite a obtenção de um material com composição majoritariamente holocelulósica, assim como foi evidenciado que o condicionador de solos produzido apresenta capacidade de retenção de água de 35 g.g-1 e 240 mmolc.kg-1 de capacidade de troca catiônica. Os testes com aplicação de 1% do condicionador produzido nos dois solos selecionados evidenciaram que no solo argiloso, o condicionador de solos elevou a água total disponível de 0,175 g.g-1 para 0,258 g.g-1, o que representou um aumento de 47%. Quando aplicado em no solo arenoso, observou-se uma elevação da água total disponível ainda mais acentuado, aumentando de 0,035 g.g-1 para 0,060 g.g-1, representando um aumento de 71%. Os ensaios de lixiviação realizados em colunas evidenciaram que o condicionador de solos desenvolvido reduziu a lixiviação dos nutrientes cálcio, potássio, enxofre, zinco e boro, evidenciando que a utilização do mesmo no solo resulta em um aumento na capacidade de retenção de nutrientes. Os resultados dos testes realizados evidenciam que o material produzido se apresenta como um produto potencial para o mercado de condicionador de solos.
Article
Full-text available
This paper presents the results of new polyelectrolytes obtained by copolymerization of maleic acid with acrylamide, hydrolysis of synthesized copolymers with potassium hydroxide, and subsequent neutralization by adding potassium dihydrogen phosphate. The properties of these PE and the possibilities of their application to improve the properties of saline soils of Karakalpakstan are investigated. The influence degree of various factors (comonomers ratio, pH of the medium, etc.) on the formation of copolymers of maleic acid with acrylamide is determined, and a possible mechanism for this process is proposed. It was found that the nature and quantitative composition of the active functional groups that determine the colloidal and chemical properties of PE substantially depend on the conditions for the synthesis of copolymers and their hydrolysis. The general and specific patterns of the structuring action of the obtained PE on the structure less saline soil dispersions were revealed. The interconnection between the effects of PE and the parameters of their macromolecules (volumes and sizes of deformed clews) is shown.
Article
The modification of desert silty sands has been a great challenge due to its relative uniform particle dimension and non-cohesion. This paper presents a study on utilizing a new additive, anionic polyacrylamide (PAM) with ordinary Portland cement (OPC) to modify the desert silty sand. Unconfined compression strength (UCS) tests were conducted to investigate the strength and durability (resistance to cyclic wet-dry and freeze-thaw damage) of modified sands at the maximum dry density; the scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) spectroscopy tests were carried out for microstructural analysis. Results reveal that the PAM fraction has a significant influence on the mechanical performance of the modified desert silty sand, and a threshold PAM dosage exists, beyond which adding excessive PAM will inhibit the strength and durability further. The microstructural analysis reveals that the physical stick-up of the PAM-to-sand particles leads to the formation of the spatial cobweb-like reticular structure. The Ca²⁺ cation released by OPC served as a cationic bridge, which in turn enhance the PAM adsorption efficiency. However, excessive PAM would play a negative role, chiefly because of the excessive accumulation between the hydrated production and sand particles. This study indicates that the combination of cement and PAM has the virtues of both cement-stabilized and PAM microfabric-reinforced sand. This binary PAM–OPC modification approach plays a more efficient role if a rational PAM incorporation (0.1–0.3% in this study) is selected.
Chapter
Agriculture is one of the main and most momentous of human inventions. At present it is an important economic activity directed mainly at the supply of food worldwide although, to a lesser extent, it is used also for the production of raw materials and energy. Unlike structural polymers, functional polymers have shown a greater spectrum of applications in the agricultural sector. Generally speaking, they are used in applications as diverse as water storage, nutrient release, and pest control. Through the use of synthetic polymers and biopolymers it has been possible to improve several agricultural production processes, the use of which does not imply a positive impact on the environment, and therefore, the simple use of polymers in agricultural applications does not mean that they have an absolute eco-friendly connotation; consequently, understanding their direct or indirect environmental impacts must be established in the specific context of their application. This chapter describes the main characteristics of functional polymers for agricultural use from a structural point of view in conjunction with an analysis of their impact on the environment.
Article
Polyacrylamide (PAM) is a polymer used in construction stormwater management as both an erosion and sediment control measure. PAM is considered one of the environmentally safest polymers on the market, however overapplication concerns dictate that large quantities in runoff be avoided. For slope erosion applications, ensuring proper concentration requires methods for testing residual concentrations. This research investigated residual concentrations of PAM when dry-applied at a rate of 25 lb/acre (28 kg/ha) for slope stabilization and subjected to 1-h of simulated rainfall following ASTM D6459-19 protocols at three 20-min successive 2-, 4-, and 6-in./h (5-, 10-, and 15-cm/h) intensities. Residual concentrations were determined by centrifuging runoff samples to remove soil and reading absorbance from an ultraviolet-visible spectrometer, comparing values to those at known concentrations. Concentrations in collected runoff samples were found to surpass values found in previous research and in other PAM applications, especially during first flush, and were high enough to affect water viscosity. An alternative application method is presented that may mitigate PAM runoff concentration. The spectrometry method was also used to highlight the possibility that polymers used in hydromulches may also deposit excess concentrations in stormwater runoff, and that formal residual testing of such products is warranted. The processes used for this study demonstrated how discharge may be monitored and regulated to minimize undesirable runoff conditions from construction sites and underscore the importance of appropriate design and implementation when using additives for erosion control.
Article
Production of vast amounts of waste material routinely has prompted the interest of researchers to conserve and manage biomass waste. The recycling of organic waste material could produce various value-added bioproducts beneficial for human beings and the environment. Traditional decomposition methods have been reported, but the efficiency of these fermentation methods was comparatively low and expensive, limiting their use. Currently, researchers have moved their concern toward green pretreatment methods, including enzymatic techniques and biological decomposition purposes. Among biological sources, the fungal fermentation system has offered a more efficient and sophisticated method because of higher production of bioproducts, greater efficiency, environmentally safe, and cost-effectiveness compared to previous methods. The present study reviewed the advantages of fungi-mediated conversion of waste-activated sludge into value-added bioproducts to help the researchers in sustainable management of waste and shed light on limitations of previous methods.
Article
Y zeolite is presently used to be an important active component in oil refining catalysts. The efficient synthesis of NaY zeolite remains many huge challenges. Herein, a novel method of...
Article
This study aims to apply thermogravimetric analysis technology to develop a facile way for long-term stability prediction of polyacrylamide-type polymers at high temperature and high salinity reservoir conditions, to maintain sufficient viscosity in chemical flooding. Pyrolysis behaviors in powder form and long-term stability in solution of nine polyacrylamide-type polymers were investigated. Activation energies of polymers determined by Coats-Redfern model were correlated with half-life from viscosity measurements to estimate stability at harsh conditions. Moreover, decomposition rates of polymer molecular weight present good correlations with half-lives, and activation energies respectively, which indicates molecular weight reduction results in solution viscosity loss.
Article
As easily fabricated, polyacrylamide (PAAm) hydrogels are widely used, especially in medicine. Material properties of these crosslinked polymers are usually tuned by varying monomer/crosslinker ratio during polymerization. However, the properties of resulting hydrogels are affected by an all-in composition of the reaction mixture. As the influence of water/monomer ratio has not been systematically studied yet, the objective of this study is to provide a comprehensive investigation of this way of hydrogel preparation together with a careful examination of resulting materials. The samples of PAAm hydrogels prepared with controlled contents of water in the reaction mixture vary in achieved swelling ratios (from 5 to 25) and rigidities (Young's modulus from 300 to 5 kPa). These material properties remain practically the same even if the hydrogels are dried and reswelled again. Performed long-time testing suggests that the PAAm hydrogels can be stored either in wet or dry state, however, to avoid possible degradation by polymer hydrolysis, they should be placed in darkness and stored at no more than room temperature. The prepared hydrogels swell more in NaCl solutions than in water. As this swelling/shrinking behavior is reversible and independent of hydrogel history, it could be applied for remote control of hydrogel properties.
Chapter
Conservation of the environment is a goal that should be inherent in all human activities. In this sense, functional polymers are used for different purposes and in many areas. Thus, even if polymeric materials are not biopolymers or are not biodegradable, their functionality is directed toward conservation of the environment, either directly or indirectly. Understanding the broad meaning of the word eco-friendly, it is clear that this condition derives in many cases from use and not necessarily from its nature. Normally, regardless of the phase, applied environmental sciences are directed at the monitoring of pollutants and remediation activities, in that same context the main applications of functional polymers are circumscribed, and therefore, these are the main topics in developing the content of this chapter. Particular emphasis is placed on applications depending on the type of ecosystem: terrestrial and aqueous ecosystems, but also, in the usual work phases: soil, water, and air.
Article
Constructed wetlands have been successfully used in the treatment of produced water brought to the surface in large quantities during oil extraction activities. However, with the increasing use of partially hydrolyzed polyacrylamide (HPAM) in enhancing oil recovery, the impacts of HPAM on the biological processes of wetlands is still unknown. Microbial mats in wetlands play a key role in hydrocarbon degradation. Here, we compared the bacterial communities of four wetland microbial mats after flooding with different concentrations of HPAM. Two mats (i.e. the HPAM-free and the 500 ppm HPAM pre-exposed mats) were selected to further investigate the effect of HPAM on respiration and biodegradation activities. The field mats exhibited clear differences in their bacterial community structure, where Cyanobacteria and Alphaproteobacteria became dominant in the presence of HPAM. In the laboratory experiments, the generated CO2 by the HPAM-free and the 500 ppm HPAM pre-exposed mats did not vary significantly when HPAM was added, although CO2 values were slightly higher in the presence of oil. Both mats were still able to degrade between 15 ± 14.4 to 50 ± 13.0% of C10 to C30 alkanes in 28 days, and this degradation was not affected by HPAM addition. The HPAM concentration decreased by 22–34% of the initial amount after 28 days of incubation in the HPAM-free mat, versus only 7–18.4% decrease in the 500 ppm HPAM pre-exposed mat. We conclude that the wetland microbial mats seem to have become well adapted to HPAM and could maintain their respiration and hydrocarbon degradation activities.
Article
Although sulfide scales of FeS, PbS, and ZnS do not occur as frequently as carbonate and sulfate scales, it is difficult to remove them once they are formed and deposited. Effective prevention and remediation of sulfide scales have not been fully developed. For sulfide scales, the conventional threshold inhibition approach is not as effective as for carbonate and sulfate scales, presumably, due to strong ion pairs formation of FeS⁰ and fast precipitation kinetics of FeSs. Polyacrylamide (PAM), polyvinyl pyrrolidone (PVP), and carboxymethyl cellulose (CMC) were examined as dispersants for sulfide scales to prevent and mitigate sulfide scale deposition through controlling the particle sizes of FeS, PbS and ZnS. PAM, PVP, and CMC dispersed FeS particles more effectively at pH 6.7 than 5.0 and temperature 70 °C than 90 °C. PAM and CMC successfully dispersed FeS particles even in extremely high ionic strength (I) of 4.6 M, while, PVP, slightly less effective, up to I = 2.6 M. At pH 5.0 and 90 °C, CMC was able to disperse FeS particles up to I = 1.3 M and PVP up to I = 0.6 M. In contrast, PAM could not disperse FeS particles at all. When FeS particles were dispersed in the presence of polymeric dispersants, FeS particle sizes remained in nanometer ranges, from 100 to 600 nm. Our results demonstrated that CMC was the best dispersant for FeS particles among the three polymers we tested. For CMC, the larger molecular weight and the lower degree of substitution of carboxylic groups on cellulose, the more effective dispersant CMC became. PbS and ZnS were also well dispersed in the presence of CMC. Almost all fraction of PbS particles was smaller than 200 nm, while about 60% of ZnS particles were smaller than 200 nm. Results demonstrated that the promising treatment selection of CMC as a universal dispersant for sulfide scales.
Chapter
Full-text available
In nature, various types of soils are distributed in such a way that they are found together. It is very much difficult to find clay, sand, silt, gravel in a pure condition. Also, these soils (clay, sand, silt, gravel) have different geotechnical properties. Although various researchers have focused on effect of clay particles on various geotechnical properties of sand–clay mixture. But, sand is available in different size and gradations. So, the effect of sand gradation and various particle size on geotechnical properties of sand–clay mixture is still not clear or very less information available about that. In this study, effort have been made to understand the effect of clay particles (kaolinite) on compaction parameters (OMC, MDD) of various sizes and gradation of sand. Experimental work involves the preparation of six samples of sand (i.e., three poorly or uniformly graded and three well graded) from procured materials. Poorly graded samples were obtained by following sand size: coarse sand (>2 mm), medium sand (>0.425 mm and <2 mm), fine sand (<0.425 mm). For preparation of well-graded samples, efforts had been made by combining two or three types of sands, i.e., coarse, medium, and fine (C + M, M + F, C + M + F). Kaolinite clay was used as cohesive fine fraction. Different amounts of kaolin clay were added in each of the sample, i.e., 0, 5, 10, and 15%. Preliminary tests were performed on all the three well graded, three poorly graded as well as on kaolinite clay in pure condition for finding out the physical properties of the soils. (i.e., Atterberg’s limits, grain size distribution, specific gravity). Relative density test was performed for finding out the density of all the sand samples at 0% kaolin content ant 70% relative value was adopted. For all other sand–kaolin mixture (5, 10, 15%) standard proctor tests were carried out. Results indicated that among all the samples (coarse + medium + fine + 15% kaolin) exhibits greater maximum dry density (MDD) and lesser optimum moisture content (OMC) while (fine + 5%kaolinite) has lesser maximum dry density and greater optimum moisture content. So, from the results we can say for (C + M + F + 15%) sample all the particles are well arranged so the gap between the particles are minimum so the MDD of the sample goes to increase.
Chapter
Construction on soft soils has always been a problem to geotechnical engineers. A review of the literature reveals that many techniques and methods have been developed to work with such soils. The technique of soft soil improvement by the installation of stone columns has become popular in recent past and has proven its application to many construction situations in soft soils. Construction of stone columns provides a new composite ground consisting of stiff stone column–soil matrix. Stone column reinforcement in the soft ground increases the bearing capacity and improves the settlement characteristics. They can be used to accelerate the rate of consolidation of soft soil deposits through a well-understood mechanism. They act as vertical drains that provide a shorter drainage path for excess pore water pressure to dissipate rapidly. In the present investigation, an attempt has been made to study the settlement characteristics of soft soil reinforced with the stone column. The main objective of the study was to investigate the settlement time behaviour of the stone column in very soft soil having undrained shear strength (cu) ≈ 5 kPa under different bearing pressures and to verify the results of the experimental results with the analytical theory on consolidation rate of composite ground. A compactive effort is applied during the construction of stone column, and its average value is equal to 21.98 kJ/m3. The settlement of the reinforced soft soil bed is reduced by 25.8% when reinforced with stone column diameter of 76.2 mm.
Article
Full-text available
As a typical water‐soluble polymer, ultra‐high molecular weight (UHMW) partially hydrolyzed polyacrylamide (HPAM) has been widely used in various industries as thickeners or rheology modifiers. However, precise determination of its critical physical parameters such as molecular weight, radius of gyration (Rg) and hydrodynamic radius (Rh) were less documented due to their high viscosity in aqueous solution. In this work, the molecular structure of five UHMW‐HPAM samples with different MW was elucidated by ¹H and ¹³C NMR spectroscopy, and their solution properties were characterized by both static and dynamic light scattering. It is found that all the second virial coefficient (A2) values are positive and approaching zero, indicating of a good solvent of 0.5 M NaCl for UHMW‐HPAM. The weight‐average molecular weight (Mw) dependence of molecular size and intrinsic viscosity [η] for these series of HPAM polymers with MW ranging from 4.81 to 15.4 × 10⁶ g·mol⁻¹ can be correlated as Rg = 3.52 × 10⁻²Mw0.51, Rh = 1.97 × 10⁻²Mw0.51, and [η] = 6.98 × 10⁻⁴ Mw0.91, respectively. These results are helpful in understanding the relationship between molecular weight and coil size of HPAM polymers in solution, and offer references for quick estimation of molecular weight and screening of commercial UHMW‐HPAM polymers for specific end‐users.
Article
Full-text available
The article reviews the literature on the state of the problem of protecting the soil cover of the earth. Today, during the period of strong pollution of the lithosphere by technogenic wastes of various nature, leading to soil degradation and erosion, in measures to improve the physical, chemical, hydrological, agronomic and other properties of soils, preference should be given to the least harmless natural raw materials. These include humic acids (HA) and their derivatives, which are good adsorbents, stabilizers and fixers of dispersed systems. The study of the composition of humic acids with various water-soluble polymers and surfactants is another not fully understood area of interdisciplinary nature. Literary search for the works of Kazakh scientists shows the underdevelopment of both the extraction of humic acids and the formation of HA interpolymer complexes (IPC) with polymers and surfactants, as well as their use as fixers, structure formers of soils subject to wind and water erosion. Having large reserves of coal in the republic, a source of humic acids, it is not forgivable not to develop an integrated approach to research on the extraction of HAs, the formation of IPC on their basis and the use of new structure-forming agents to improve the degraded soils of the republic's structures.
Article
Most natural thickeners do not have a full coverage degree when printing on dark dyed fabrics (brown/navy/black). Therefore, some materials are added to improve their coverage. It is common practice that printing is done on dyed or undyed fabrics. The dyed fabrics are of different shades, so the printing process faces a problem, as most of the natural thickeners do not have full coverage, especially those extracted from aloe vera and flax seeds when printing on fabrics dyed with dark colors. Therefore, in this study the effect of adding zinc oxide and titanium oxide to the printing paste was studied. The result confirmed that, adding metal salts to printing paste using aloe vera gel or flaxseeds gum as thickener increases the whiteness index of these pastes as well as the printed fabric. In addition, using light dye in these printing paste provides good covering of dark color with good appearance of the new light color used. Furthermore, the mechanical and physical characteristics of printed textiles with various thickeners and metal oxide (14 %) have been evaluated and provide improving both tensile strength and elongation at break and had no effect on the angle of crease recovery of printed textiles across all printing paste formulations.
Chapter
Polyacrylamide is a water-soluble synthetic polyelectrolyte which consists of repeating units (forming a chain structure and containing hydrophilic groups). Due to the different nature of the groups present in the macromolecules, polyacrylamides can be divided into nonionic, anionic, and cationic ones. They are used in many industries, including mineral processing; wastewater treatment; production of paints, inks, varnishes, plastics, paper, cosmetics, and ceramics; pharmacy, food industry, or in agriculture as polymeric additives controlling soil erosion process. The addition of high molecular compounds affects the rheological properties and stability of colloidal suspensions. Their presence in the system can increase or decrease its stability. Stabilization or flocculation may result from the adsorption of high molecular compounds in various conformations on the surface of the solid particles dispersed in liquid phase or from the presence of nonadsorbed polymer chains in the dispersion phase. This paper aims to review polyacrylamides structure, synthesis methods, and their adsorption on the surface of clay minerals. The literature studies on the impacts of PAM adsorption on clay particles’ aggregation and heavy metal ions’ accumulation in soil environments have been also presented.
Article
Full-text available
Rapid urbanization has created an enormous pressure on land, thereby creating a need to improve the geotechnical properties of soil which are deemed inadequate for construction purposes. A variety of soil stabilization techniques are in vogue off-late, ranging from reinforcing techniques to application of chemical stabilizers to improve the geotechnical properties of soil. An attempt has been made to use a natural resin, pre-gelatinized starch to improve the properties of soil. Pre-gelatinized starch has been added in quantities of 0.5, 1 and 1.5 percentages to soil. Soil samples are prepared as per IS: 2720 (Part 1)-1983specifications. Geotechnical properties like specific gravity, permeability, compaction characteristics and strength were investigated. The results of the study show that the addition of pre-gelatinized starch improved the geotechnical properties of the soil favorably. Permeability of the stabilized soil decreased and the strength improved significantly. Pre-gelatinized starch, a natural substance is environment friendly and aids sustainable development. The durability studies show that it is also not susceptible to decay under adverse conditions. © 2018, Institute of Advanced Scientific Research, Inc.. All rights reserved.
Article
Full-text available
The objectives of this rainfall simulator study were to: 1) determine the effect of drying of crusted vermiculitic soil on the subsequent crust properties and infiltration rate (IR) values, 2) determine the effect of polymers applied at low concentration in irrigation water of two qualities on the IR under consecutive water applications, and 3) determine the effectiveness of polymer applications to the soil as would be required under rainfall conditions. Except for polyacrylamide the polymer applications were relatively ineffective in subsequent sprinkler applications with plain water applied with impact energy. The beneficial effects were preserved under water application without impact energy. Spraying concentrated polymer solutions on the soil surface was not effective in preventing crust formation by following rain events except for the case when cationic polysaccharide guar with lower charge density was sprayed on in a CaCl2 solution. The results are explained on the basis of polymer adsorption and penetration into the soil surface layer and aggregates. -from Author
Article
Full-text available
Soil erosion is a serious problem threatening sustainability of ag- riculture globally and contaminating surface waters. The objective of this study was to determine whether low concentrations of anionic polymers in irrigation water would appreciably reduce irrigation fur- row erosion on Portneuf silt loam (coarse-silty, mixed, mesic Durix- erollic Calciorthid), a highly erodible soil. Furrow slope was 1.6%, furrow length was 175 m, and irrigation rates ranged from 15 to 23 L min-'. Inflow during the first 1 to 2 h of the first 8-h irrigation was treated. Subsequent irrigations were untreated. Polyacrylamide (PAM) or starch copolymer solutions were injected into irrigation water en- tering furrows at concentrations of 0, 5, 10, and 20 g m- 3. Sediment loss from polymer-treated furrows was significantly less than that of control furrows in the first (treated) and second (untreated) irriga- tions, but not in the fourth (untreated). The PAM provided better erosion control than the starch copolymer. Efficacy of PAM treat- ments varied depending on its concentration, duration of furrow ex- posure, and water flow rate. In the initial (treated) irrigation and at low flow rates, 10 g III -3 PAM reduced mean sediment load by 97% compared with untreated furrows. Residual erosion abatement in a subsequent irrigation, without further addition of PAM, was approx- imately 50%. The PAM increased net infiltration and promoted greater lateral infiltration. Effective erosion control was achievable for a ma- terial cost below $3 ha-' irrigation-'.
Article
Full-text available
The absorption of unchanged polymers by clays is largely 'entropy-driven'. The adsorption isotherms are typically of the high-affinity type, and there is an apparent lack of desorption on dilution. The interactions of clays with biopolymers, such as proteins, nucleic acids, and polysaccharides, can be rationalized in similar terms. Polyanions are effective as flocculants because of their large 'grappling distance' whereas unchanged polymers are better suited as soil conditioners because they can spread over adjacent clay/soil particle surfaces like a coat of paint. -from Author.
Article
Full-text available
We grew tomato, cotton, and lettuce seedlings in containers in a glasshouse in various soils with different combinations of a polyacrylamide and a polysaccharide as soil conditioners. In some tests all soil conditioners were applied in solution, and in other tests part was applied in solution and part mixed dry into soil. The conditioners increased rate of emergence and dry weights of seedlings. Results were similar to those for Krilium over 30 years ago, but application rates for the soil conditioners used in this study were much smaller. (C) Williams & Wilkins 1986. All Rights Reserved.
Book
Although several monographs and reviews have appeared on individual polymers of this type, and their applications and other technical aspects have also been discussed, this is apparently the first book to deal with the physical chemistry of water-soluble synthetic polymers as a group. This collective survey enables their properties and behaviour to be compared, and to be correlated with their molecular structures for predictive purposes. However, this has made it necessary to critically re-appraise much of the earlier fundamental work, so that current discussion of more recent work can be put on ta proper basis. Thus, of the 1800 or so references cited, the middle two-thirds related to the twenty-year period centred on about 1968. Nevertheless, sufficient key recent references have also been included so that the existing state of the art is delineated.
Article
The effects of low concentrations of two polymers, an anionic polyacrylamide (PAM) and a cationic polysaccharide (PSD), on soil permeability and erosion from a grumusol and a loess, were studied during five consecutive irrigations of 60 mm each. During the first three irrigations of water and polymers, the final infiltration rates (FIR) of the soils were significantly higher than those of the untreated samples (control). In the subsequent two irrigations with water only, the FIR values of the treated samples decreased to values similar to those of the control. Soil losses in all the PAM treatments were significantly lower than those in the PSD treatments. Both polymers stabilized soil aggregates, but PAM also cemented aggregates together and increased their resistance to erosion. -from Authors
Article
The impact energy of water droplets from rain or overhead sprinklers can cause a seal to form at the soil surface. This constitutes a severe problem in agricultural lands in arid and semiarid regions. Spreading a soil conditioner on the surface of the soil and providing a constant supply of electrolytes may prevent seal formation. PAM + electrolyte treatments decreased soil erosion by more than one order of magnitude compared with the control. -from Authors
Article
Knowledge of adsorptive behavior of polymers is useful in predicting their mobility in soil, depth of effective treatment, and other factors related to soil physical conditions. Adsorption isotherms were determined by batch technique for six tritium labeled polymers on three soils, one of which was pretreated to create a high exchangeable sodium percentage (ESP) of 34, and on washed quartz sand of three size fractions. The three anionic polyacrylamide (PAM) compounds had negative charge density of 40J > 21J > 2J, and the three polysaccharide compounds (guar) had a higher positive charge (T-4141), a lower positive charge (CP-14), and a negative charge (T-4246). Adsorption of CP-14, 21J, and T-4246 was measured on montmorillonitic clay extracted from one soil and a specimen sample of montmorillonite clay. Adsorption of a given polymer on the low ESP soils was not significantly different, but was significantly higher on the high ESP soil. The adsorption isotherms were T-4141 ≥ 21J > CP-14 ≫ 40J ≥ 2J > T-4246, and adsorption on sand was only a little less than on soil. The adsorption on clay was CP-14 ≫ T-4246 > 21J. The data suggest that the PAM and guar polymers studied do not penetrate the aggregates, because adsorption was approximately the same for all soils of similar aggregate sizes. Molecular size, molecular conformation, and electrostatic charge each significantly affected the adsorption isotherms.
Article
Since some uses of acrylamide could cause ground water contamination, potential hazards were assessed by evaluating the degradation and leaching of 14C-acrylamide (labelled at the carboxyl position) in 4 soils: silt loam, clay loam, loamy fine sand, and loam. The soil degradation study utilized the biometer flask method. Acrylamide half-life (t(1/2)) was estimated by the time required for release of one-half the evolved 14CO 2. Half-life was influenced by incubation temperature, acrylamide concentration, and the season at which the soil was collected. At ambient temperature (22°C), half-lives ranged from 18 to 45 hr for 25 ppm acrylamide (on a soil basis). Decreasing temperature or increasing acrylamide concentration increased half-life. Half-life was 2 and one-half times greater in soil gathered in spring than the same soil gathered in summer. When acrylamide was incubated in anaerobically maintained soil, it apparently metabolized more slowly. Leaching was evaluated by soil TLC. R(f) values, which ranged from 0.64 to 0.88, place acrylamide into the 'mobile class'.
Article
In and and semi-arid regions, where soil structure is unstable, surface runoff due to seal formation reduces irrigation water use efficiency. This study was conducted to determine the efficiency of surface treatments in reducing runoff and increasing wheat crop productivity. Surface runoff from wheat plots on a non-sodic, silty clay loam soil (Rhodudalf silty clay loam), sprinkler irrigated with a good quality irrigation water, was collected using flumes and collection boxes. Percentages of runoff wer6 36.1% of the total irrigation during the growing season for the control (Ct), 12.8% for phosphogypsum (PG), 1.4% for polyacrylamide plus PG (PAM), and 1.1% for pitting plus PG (Pt) treatments. The mulching effect of the growing canopy did not reduce runoff during consecutive irrigations as the season progressed. Water content in the profile was correlated with the amount of water that infiltrated into the soil. The crop biomass production in the Pt and PAM treatments was significantly higher than the PG and Ct treatments (8.81 and 7.91 vs. 6.41 and 5.47 Mg ha⁻¹, respectively). The Pt and PAM treatments also gave significantly higher grain yield (3.66 and 3.02 vs. 2.25 and 2.12 Mg ha⁻¹, respectively). The Pt, PAM, and PG treatments resulted in significantly higher irrigation water use efficiency (IWUE) than the Ct. The PAM is the least known treatment and is given special attention in this study. In regions where water is scarce and costly, improving the efficiency of irrigation by tillage or soil ameliorants should be considered. Please view the pdf by using the Full Text (PDF) link under 'View' to the left. Copyright © . .
Article
This reviews 509 articles via 505 refs. cover the period 1906–80. It surveys acrylamide preparation, polymerization by radiation and handling. A cheap method for PAM production is prospected.Chemical and technological means of solving tillage problems, soil reclamation and arable land creation are reviewed. The role of PAM on soil physico‐chemical properties, irrigation requirements and crops yield is discussed. Modification of PAM for imparting chemical and bacteriological fertilities besides conditioning soils is also prospected. This possibly creates cheaply arable fertile lands.
Article
Although the effects of polymers on various soil physical properties have been investigated, adsorption of polymers by soils has not been extensively studied. Adsorption isotherms were determined by the batch technique for three tritium-labeled polyanions on one soil which received various pretreatments. No direct association between the amount of adsorption and aggregate stability was found. The general effectiveness of the polyanions for improving aggregate stability of the natural soil was in the order 2J > 21J > 4246. The reverse trend was observed for the Na soil. -from Authors
Article
Acrylamide is a potential ground-water contaminant and is a known neurotoxin to man. Thus, information about its fate in soil is desired. The fate of N in acrylamide added to five soils was studied by performing analyses for NH3, NH4+, NO2-, and NO3- after incubation of acrylamide-treated soils for various times. The results showed that acrylamide-N is readily hydrolyzed in field-moist and air-dried soils under aerobic and waterlogged conditions and that acrylamide-N is converted to NO2- and NO3- under aerobic conditions. The percentage of acrylamide-N recovered as inorganic N increased with increasing temperature (10-30°C) and incubation time (2-21 days). After 3 days of incubation at 30°C under aerobic conditions, the percentage of acrylamide-N recovered as inorganic N ranged from 11% in Clarion soil to 76% in Canisteo soil. The corresponding recovery values after 14 days of incubation were 74% and 94%, respectively. Generally, the results with field-moist soils were similar to those obtained with air-dried soils. The recovery of acrylamide-N after 21 days of incubation under waterlogged conditions at 20° C ranged from 76% in Harps soil to 93% in one sandy (Chelsea) soil. Expressed as percentage of acrylamide-N added, the NH+-N produced in Clarion, Fayette, Harps, and Canisteo soils after 7 days of incubation under waterlogged conditions ranged from 18% in Clarion soil to 38% in Canisteo soil. The corresponding values after 21 days of incubation were 81% and 90%, respectively. Significant amounts of NH3 were volatilized from sandy and calcareous soils treated with acrylamide.
Article
An iron-inefficient cultivar of soybean (Glycine max L. Merr. Bragg cv. PI-54619-5-1 was grown in two different calcareous soils, a Natrargid and a Torrifluvents, to determine if improvement of soil aeration with a synthetic polyacrylamide as a soil conditioner would decrease the tendency of the cultivar to lime-induced chlorosis. The results suggest that when soil is well aerated with good drainage from use of the soil conditioner, the iron status of plants is improved.
Article
The adsorption of a family of polysaccharides (guar) and a family of polyacrylamides (PAM) by clays from aqueous solutions was studied. Silver Hill illite (IM-1) was equilibrated with two synthesized waters which represented the quality of the Friant-Kern Canal water and of well water used for irrigation in the San Joaquin Valley of California. The order of adsorption of the polymers was cationic > nonionic > anionic in all systems. The cationic and nonionic polymers adsorbed to a larger extent from the canal water than from the well water, whereas the anionic polymers displayed a higher adsorption from the well water. The results suggest that the adsorption of the polymers occurred mainly on the external surface of the clay packages. The pore size distribution in these micro-aggregates had a dominant effect on the adsorption of the polymers. The water quality also influenced the adsorption considerably. The higher the electrolyte concentration, the higher was the rate of clay flocculation, and the fraction of the surface area which was found inside the intra-aggregate cavities was, hence, less accessible. The competition between inorganic cations and the cationic polymers adsorption for sites on the negatively charged clays also increased with the electrolyte concentration. -from Authors
Article
We grew wheat (Triticum aestivum L. cv. INIA66R) and tomato (Lycopersicon esculentum Mill. cv. Tropic) in containers with a Xerorthents soil and with levels of an anionic soil conditioner far in excess of that needed for adequate stabilization of soil. The 1% rate increased the vegetative growth of plants over controls, and the 5% rate gave yields more nearly like controls. The anionic polymer decreased accumulation of the anions P and Si in all plants and decreased Mn and B in wheat only. The highest level of polymer also depressed accumulation of some of the macroelement cations. Both levels of polymer created 100% water-stable aggregates compared with only 38% in the control. The potential for toxicity of polyacrylamide soil conditioners is discussed. (C) Williams & Wilkins 1986. All Rights Reserved.
Article
Polyacrylamide was tested on furrow-irrigated cotton to assess its ability to improve infiltration on a Holtville silty clay loam (50% clay fraction consisting of 45% montmorillonite). Application was more effective as dilute solution in irrigation water than as dry powder on the soil surface. Solution concentration of 25, 50, and 150 mg L-1 (6.6, 13.3, and 32.2 kg ha-1) were tested; the highest amount increased the infiltration rate of subsequent irrigations by 30 to 57% during the first 4 h. Final infiltration rate (after 12 h) and total water infiltrated were not increased by the polyacrylamide application, indicating that surface-sealing is not the limiting factor to permeability of soils with a high fraction of swelling clay. (C) Williams & Wilkins 1986. All Rights Reserved.
Article
In soils exposed to rain, aggregate disintegration is the first process which leads to seal formation. The objective of this study was to evaluate the relative importance of aggregate stability in seal formation. The effects of raindrops' impact energy, exchangeable sodium percentage (ESP), electrolyte concentration in the applied water, and addition of an anionic plyacrylamide (PAM) on aggregate stability and seal formation were studied on three smectitic cultivated soils from Israel using laboratory drip-type rain simulators. Aggregate slaking took place much faster than seal formation; only 9 mm of rain were needed to disintegrate the aggregates compared with >40 mm of rain needed for seal formation. Soil ESP enhanced aggregates' breakdown at the upper ESP range, whereas the effect of ESP on seal formation was at the lower ESP range. Electrolyte concentration in the applied water had no affect on aggregate disintegration but affected the rate and final infiltration rate of the seals formed. Adding PAM to the soil improved aggregate stability and increased the permeability of the seal. Aggregate breakdown was suggested as the first step in seal formation, to be followed by surface compaction and clay dispersion. (C) Williams & Wilkins 1992. All Rights Reserved.
Article
Seals formed at the soil surface during rainstorms reduce rain penetration and cause runoff and erosion. We studied the effect of surface application of an anionic polyacrylamide (PAM) at rates of 10, 20, and 40 kg.ha-1 on the infiltration rate (IR) of two soils, a loess (Calcic Haploxeralf) and a grumusol (Typic Chromoxerert), during simulated rainstorms. We determined the interaction between PAM and electrolyte concentration at the soil surface under a simulated rainfall of distilled water or tap water and by spreading gypsum. Electrolytes in the soil solutions that flocculated the soil clay enhanced the beneficial effect of the polymer on aggregate stability and greatly reduced water losses. Complete drying of the polymer-soil surfaces improved the binding action of the polymer. Treatments with PAM under optimal conditions increased the final IR of the loess from 2.0 to 23.5 mm.h-1 and increased rain intake of an 80-mm rainstorm from 12.3 to 64.2 mm. PAM treatment of the grumusol increased the final IR from 3.0 in the control to 20.5 mm.h-1 and the rain intake from 21.3 to 62.3 mm. As soils from semiarid regions are unstable, form crusts, and produce much runoff (80%) during rainstorms, the use of PAM to reduce runoff should be considered. (C) Williams & Wilkins 1990. All Rights Reserved.
Article
I grew tomato (Lycopersicon esculentum Mill. cv. Tropic) plants for 26 d from transplanting in full nutrient solution with and without polymers in nutrient solution at two different pH values. An anionic polyacrylamide and a polysaccharide (from guar bean) each at 100 mg L-1 in solution slightly improved yields at both pH values. A cationic polymer at the same concentration decreased yields. There were no apparent nutritional reasons for the effects. (C) Williams & Wilkins 1986. All Rights Reserved.
Article
The objective of this study was to observe the effects of irrigation method and polyacrylamide additions on selected soil physical properties. Polyacrylamide (PAM) was applied to fallow clay loam soil to the rate of 650 kg ha1. The PAM-treated plots were flood-irrigated at the rate of 5 cm wk-1. Untreated plots were either flood-or sprinkle-irrigated. Measurement of soil physical properties included bulk density, penetrometer resistance, aggregate stability, and infiltration rate. The surface bulk densities of sprinkle-irrigated soil and PAM-treated, flood-irrigated soils were significantly lower than the flood-irrigated control. The presence of a surface soil crust in the flood-irrigated control was evidenced by penetrometer resistance 10 times greater than the PAM or sprinkle-irrigated treatments. Aggregate stability was immediately improved from 17 to approximately 80% by the application of PAM. Improved aggregate stability (approximately 50%) lasted throughout the experiment. Infiltration rates of the PAM and sprinkle-irrigated treatments were approximately twice as great as those of the flood-irrigated control. (C) Williams & Wilkins 1986. All Rights Reserved.
Article
Polyacrylamide polymers are useful in forming water-stable aggregates in soil. They not only have a favorable effect on water infiltration in soil, but also decrease the erodibility of soil. To stabilize soil, the polymers are either mixed dry with soil and then subjected to a wetting, drying, and cultivation cycle or solutions containing polymers are applied to cultivated soil. Five diferent situations where polymers can decrease soil erosion are described. The first situation involves application to soil several centimeters deep to improve water penetration, so that there is less water runoff and less erosion. The second situation involves application to the surface up to a 2-cm depth of soil to create water-stable aggregates that resist erosion. The third situation involves spraying polymers in solution or applying dry material followed by wetting onto the soil surface, so that after drying the stable structure of the surface of soil will not easily break during rain storms, even thought water will penetrate, but with much running off. The soil may not be cultivated in this situation. The fourth situation involves applying polymers to soil via irrigation water to decrease soil erosion by the irrigation water, particularly from furrows. The fifth situation involves applying polymers to driveways and playing fields to decrease erosion of dust by wind. Tested rates of the polymers that inhibited erosion were much lower than those rates used for the product Krilium over 30 years ago. (C) Williams & Wilkins 1986. All Rights Reserved.
Article
We applied new-generation soil conditioners to sodic soils in various procedures. In flocculation tests, followed by wet-sieving, particle sizes were approximately four to five times larger with new soil conditioners than with an older soils Conditioner (Krilium) or with controls. Water penetration was greatly improved on a sodic soil when conditioned with the new soil conditioner. A Natrargid soil was amended with NaCl, NaHCO3, and NaOH to give different degrees of sodicity. Application of polyacrylamide in solution to all the soils increased seem emergence and dry weights of tomato seedlings. (C) Williams & Wilkins 1986. All Rights Reserved.
Article
Acrylamide was polymerized at high monomer concentrations (25-50 wt %) at temperatures between 40 and 60-degrees-C with potassium persulfate as the initiator. The rate of polymerization was found to be proportional to the monomer concentration to the 5/4th power, a dependence extensively reported at low and moderate levels, suggesting that the rate order is invariant to the acrylamide concentration up to its solubility limit in water. Limiting conversions have also been observed and are reciprocally related to the initial monomer concentration. Both the high rate orders and limiting conversion are found to be manifestations of the same phenomena: the monomer-enhanced decomposition of potassium persulfate. A "hybrid cage-complex" mechanism, in which hydrogen bonding between the monomer and initiator lead to association, has been derived. This postulates that the monomer-initiator associate leads to donor-acceptor interactions between the amide and the persulfate. The decomposition of this charge-transfer complex leads to a secondary initiation reaction, which proceeds in competition with and often in preference to the thermal bond rupture of the peroxide. It will be shown to give good quantitative prediction of the polymerization rate order, monomer and initiator consumption, and molecular weight. Furthermore, the mechanism avoids the free-energy inconsistencies characteristic of prior theories and is generalizable to other nonionic and ionogenic acrylic water-soluble monomers in polar solvents.
Article
The soil conditioner Krilium failed some 30 years ago because it was too expensive, too difficult to use, and the results were inconsistent. Advances in polymer chemistry have made possible a new generation of water-soluble polymers which with new application techniques can largely overcome the problems associated with Krilium. Some new polymers have molecular weights 100 or more times than Krilium, and for some purposes the application rate need be only 1/100 that used for Krilium. High efficiency of use can be obtained when water-soluble polymers are applied in irrigation water to newly tilled soil to stabilize existing aggregates. Experiments in which water-soluble polymers were applied in solution to seedbeds indicate that as little as 2 kg ha−1 prevents surface crusting of soil when at least 1/4 cm of irrigation water is applied with the polymer. Effective rates vary with clay content of soil and amount of soil organic matter. Some synergistic effects on plant growth are often observed when polymer and organic matter are applied to soil simultaneously. The physical properties of soil are improved throughout the plow depth with application rates somewhat higher than 2 kg ha−1 polymer with irrigation water carrier. Benefits include improved soil aeration, water conservation, and control of erosion of soil. Laboratory testing of soil helps to guide use of water-soluble polymers and can show which of cationic and anionic polymer should be used for a given soil. Some soils respond more if some soluble Ca is also applied.
Article
The approach in this study of runoff and erosion control on steep slopes was to combine soil stabilizers with the planting of drought-resistant, perennial plants.The effect of 10 t ha−1 phosphogypsum (PG) + 70 kg ha−1 polysaccharide (PS), 10 t ha−1 PG and 20 kg ha−1 polyacrylamide (PAM), and 200 kg ha−1 PS on the erosion of steep slopes (30–60%) was studied in plots 2 m in width and of different lengths (12–20 m), at three of different sites in Israel (semiarid conditions), and under natural rainfall conditions. Likewise, observations on the establishment and development of nonirrigated, drought-resistant, perennial plants on steep slopes (40–60%), combined with 10 t ha−1 PG + 70 kg ha−1 PS, were conducted at two sites in Israel.PS + PG and PAM + PG treatments were very efficient in erosion control in a wide range of soil types, ESP, CaCO3 level, and weather conditions. These treatments reduced erosion six- to eleven-fold in comparison with the control. No significant difference was found between PS + PG and PAM + PG treatments. However, the application of PAM was problematic due to its very low dissulution rate and its high viscosity in water. Two-hundred kg PS without PG was found efficient only at one experimental site with calcic haploxeralf soil and 300 mm average annual rainfall.The combination of PS + PG, and drought-resistant, perennial plants was very sucessful. The plants developed very well without irrigation throughout the long, dry summer. Only one year later, the creeper plant canopy covered an area of 0.75–1.5 m, and the bushes were 0.8–1.2 m in height.
Article
Following promising laboratory results the effect of low concentration applications of a polyacrylamide soil conditioner SEPARAN AP30 on soil properties was tested under field conditions in a severely degraded semi-arid region in northern Kenya. Tests of conditioner performance on tilled and undisturbed soils were carried out under simulated rainfall on crusting Eutric or Calcaric Fluvisols at two sites on alluviolacustrine flats adjacent to Lake Baringo. Tests were carried out in two series separated by up to six weeks of sunshine and natural rainfall, to determine the longevity and residual effects of conditioner application.Runoff generation and soil loss were significantly reduced on all runoff plots during the first rainfall simulation, but the most dramatic results occurred when conditioner application was combined with raking. This inhibited crust development and virtually eliminated runoff and soil loss. Under natural weathering, surface crust had developed on all plots before the second rainfall simulations. Some residual effects of the conditioner on infiltration rates were still noted, but the residual effect on soil loss was greatly diminished.The tests indicate that low concentration applications of SEPARAN are not useful on undisturbed soils, but can provide useful temporary reductions in sheet and rillwash hazard when combined with tillage and could be effectively combined with grass re-seeding for more permanent reclamation.
Article
Novel experiments which involved the dosing of acrylamide into an activated sludge sewage works, a biological filter sewage works, and a river which discharged into an estuary were performed during the period from October 1979 to July 1980. In order to assess the ability of a sewage works to degrade acrylamide, an activated sludge and a percolating biological filter plant were exposed to constant dosings of acrylamide. Little loss of acrylamide occurred in either the primary or the final settlement tanks. Approximately 50% of dosed acrylamide was lost from both the activated sludge tanks and the biological filter beds. Laboratory experiments were used to help explain the in situ results. In another study acrylamide was dosed into a stream continuously for 74 days in order to assess the initial in situ adsorption and degradation, and the possibility of initiating further in situ degradation owing to acclimatisation of microheterotrophs. Dilution effects owing to ground water infiltration and additional tributaries were allowed for by monitoring both acrylamide concentration and river flow at various stations downstream of the source of acrylamide addition. The resulting quantitative mass flow study showed that no in situ loss of acrylamide occurred for a stream retention of 4–5 h. Incubations in the laboratory of collected water samples suggested some possible increase in degradative ability of the samples which had been exposed to acrylamide. A qualitative assessment of the insect fauna before, during and after exposure to acrylamide showed a reduced species diversity to occur within 5 h when exposed to 50 μg 1−1 acrylamide. Within 21 days only Hydropsyche instabilis was observed in the river. Some recolonization was noted following cessation of acrylamide dosing.
Article
Rapid biodegradation of acrylamide monomer (100–700 h) occurs in natural and polluted environments. Sterilisation of environmental samples inhibits degradation, while the seeding of a sterilised sample with unsterilised sample facilitates degradation. Certain detrital-decomposing organisms which occur in aerobic light anaerobic and dark anaerobic conditions in natural and polluted aqueous environments appear to possess the capability to degrade acrylamide. No chemical degradation occurred in 2000 h in sterile environmental samples over the pH range 4–10. The industrial addition of strong acids, bases, oxidising or reducing agents to process waters may facilitate the chemical degradation of acrylamide.
Article
Rapid degradation of acrylamide monomer in non-sterile environments (Brown & Rhead, 1979; Brown et al., 1980; Croll et al., 1974) prevented long-term analysis of the adsorption of acrylamide by sludges, etc. under environmental conditions. Short-term experiments designed to ascertain the extent of adsorption of acrylamide by peat, sludges and sediments suggested that no significant adsorption had occurred. No acrylamide was removed from sterilised river water by clays (montmorillonite, kaolinite), anionic, cationic and hydrophobic resins at various pH values and concentrations. Activated carbon was found to have a limited affinity for acrylamide which was not affected in the pH range tested.
Article
Quantitative information on adsorption- desorption of polymers on soil helps in predicting the depth of effective polymer treatment. Desorption of six tritium labeled polymers from three soils and an acid washed quartz sand was measured. Three anionic polyacrylamide (PAM) polymers whose charge density was in the order of ; two cation polysaccharide (guar) polymers whose charge density was greater for T-4141 than for CP-14; and an anionic polysaccharide (T-4246) were investigated. After 30 g of soil has been equilibrated with 20 mL of polymer solution, the supernatant was replaced by distilled water and the amount of polymer desorbed was calculated. Additionally, one soil was dried under the laboratory hood after decanting the supernatant before adding distilled water. Very little or no desorption occured when the material was kept wet. All 2J and 59 to 76 percent of the other polymers left in solution after decanting became irreversibly bonded to the soil by drying the soil.
Article
Polyacrylamide resins (Separan NP10 and AP30 flocculants) are high molecular weight polymers with low single oral toxicity to rats. Long-term feeding studies of these resins have involved three two-year studies in rats, one one-year study in dogs, and one two-year study in dogs. These poly-acrylamides are quite low in repeated oral toxicity. The laboratory animals tolerated 5–10% in their total diet without effects other than those believed to be attributable indirectly to the large, hydrophilic, nonnutritive bulkiness of the materials. The unequivocal “no ill-effect” levels were 1% in the diet of rats and 5–6% in the diet of dogs.Studies with carbon-14 tagged resin indicate that negligible amounts of polymer, if any, pass through the walls of the gastrointestinal tract of the rat. Fish were maintained in water containing 1000 ppm of these resins for 5 days and 100 ppm for 90 days without apparent adverse effect. Environmental health and medical surveys of industrial personnel confirm the low degree of hazard associated with these materials. Adequate bases exist for establishing the safety of these products from the public health aspect for many applications wherein small amounts may possibly occur in the food or drink of animals or human subjects.
Polyacrylamide Water-soluble Resins
  • W H Montgomery
Montgomery, W.H. 1968. Polyacrylamide, pp. 175-190. IN: R.L. Davidson and M.S. Sittig (eds.) Water-soluble Resins. 2nd edition. Reinhold Book Corp., New York, NY.
Rigid, highly carboxylated ionic polymers Ionic Polymers
  • A D Wilson
  • S Crisp
Wilson, A.D. and S. Crisp. 1975. Rigid, highly carboxylated ionic polymers, pp. 208-257. IN: L. Holliday (ed.) Ionic Polymers. Chapman and Hall, New York, NY.
Anionic polyacrylamide treatment of soil improves seedling emergence and growth. HortScience 22:951. acrylamide by the spiking of the waters of two sewage works and a river
  • A Wallace
Wallace, A. 1987. Anionic polyacrylamide treatment of soil improves seedling emergence and growth. HortScience 22:951. acrylamide by the spiking of the waters of two sewage works and a river. Water Res. 16:579-591.
Polymers as Soil Conditioners and Sealing Agents
  • M Aslam
Aslam, M. 1990. Polymers as Soil Conditioners and Sealing Agents. Pakistan Academy of Sciences, Islamabad.
New chemicals for water treatment
  • Housing
Housing and Local Government Committee. 1969. New chemicals for water treatment. Water Treat. Exam. 18:90-91.