No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Removal of Contaminants from Industrial Lean Amine Solvent Using Polyacrylamide Hydrogels Optimized by Response Surface Methodology
Abstract
Response surface methodology (RSM) based on a three-level, three-variable model was used to optimize the preparation parameters of a hydrogel consisting of acrylamide (AAM) as monomer, N,N'-methylenebisacrylamide as cross-linker and ammonium peroxodisulphate as initiator. Considering percentage removal of total metal ions (contaminants) as the treatment response, the effects of three variables, namely, wt% AAM, wt% cross-linker and temperature of polymerization were investigated. The polyacrylamide (PAAM) hydrogel was obtained as small beads and optimized using RSM. The hydrogel was used for the removal of total metal ions and total organic acid anions (known as heat-stable salts, HSSs) from industrial lean methyl diethanolamine solvents (MDEA, 50 wt% used by Gasco, Habshan, Abu Dhabi for natural gas sweetening). The presence of heavy-metal ions and HSS is responsible for many problems such as corrosion, foaming and fouling of the equipment. The PAAM hydrogel was characterized by determining its cross-link density and diffusivity. Scanning electron microscopy and Fourier transform infrared spectroscopy analysis of the polymeric hydrogel explained the adsorption process. Using the best-prepared hydrogel, the percentage removal of total metal ions and total organic acid anions was 74% and 24.26%, respectively. According to the Langmuir model, the maximum adsorption capacity of the hydrogel for total metal ions was 1.876 m equivalence/g and 7.686 mg/g for organic acid anions. The adsorption kinetics obeyed pseudo-first-order model for metal-ions removal and the highest rate of chromium ion adsorption was observed at pH 10.33. The desorption studies showed that the percentage removal was consistent across five cycles of adsorption and desorption.
... Our previous studies reported that the recovery of MDEA by adsorption is the most promising technology, because it is low cost, highly efficient, easy to operate, and simple in design [12,13]. In adsorption technology, hydrogels, a class of physically or chemically cross-linked three-dimensional hydrophilic polymers that can retain excess amounts of water, have shown great potential for recovering lean MDEA solvents [14]. Hydrogels based on sodium alginate (Na-Alg), a nontoxic natural polysaccharide derived from brown algae, are promising and widely used due to their unique properties, such as non-toxicity, water solubility, biodegradability, and low cost. ...
... A simple free-radical solution polymerization was used to prepare IPN hydrogels with a starting solution consisting of sodium alginate (Na-Alg) and acrylamide (Aam), cross-linker (BIS), and initiator (APS). First, sodium alginate (1.0 wt%) and acrylamide (10.0 wt%) were added and dissolved in deionized water with magnetic stirring overnight at room temperature [14,17]. Successively, 300 µL of APS solution (5.0 wt%) and µL of saturated BIS solutions were added to 6.0 mL of the alginate-acrylamide mixture. ...
Natural gas can be sweetened by removing acidic gases with aqueous methyldiethanolamine (MDEA) solvents. Heavy metal ions and total organic acid anions (TOA) contaminate the industrial lean MDEA during this process. Continuous accumulation of these impurities creates operational problems, such as corrosion, fouling, and foaming of the operational unit. In this study, a series of interpenetrating network (IPN) nanocomposite hydrogels based on sodium alginate and acrylamide were successfully synthesized in the presence of fillers, such as silica (Alg-Aam-SiO2), polyaniline-coated silica (Alg-Aam-PA-SiO2), graphene oxide (Alg-Aam-GO), and thermally reduced graphene oxide (Alg-Aam-TRGO). The synthesized IPN hydrogels were applied for the adsorption of TOA and heavy metals (chromium and iron) simultaneously from lean MDEA. Different characterization techniques, such as FTIR, Raman, TGA, XRD, SEM, TEM, and equilibrium swelling studies, were performed to understand the superiority of the hydrogels. The maximum monolayer adsorption capacity of TOA anions at 53 °C was 21.45 mg/g for Alg-Aam, 23.47 mg/g for Alg-Aam-SiO2, 20.16 mg/g for Alg-Aam-PA-SiO2, 19.19 mg/g for Alg-Aam-TRGO, and 15.29 mg/g for Alg-Aam-GO. Thermodynamically, the adsorption of all contaminants was favorable, spontaneous, and endothermic. The produced Alg-Aam-based nanocomposite hydrogels are a great candidate for purifying the contaminated lean MDEA solvents.
... Also, the shape and the mechanical rigidity of the adsorbent promote the separation procedure at the end of the adsorption experience. Various studies have investigated the PAAM hydrogel as a heavy metals adsorbent, such as the removal of mercury ions from aqueous solutions by Ramadan et al. (2010) (16); the removal of chromium ions from industrial lean methyl diethanolamine solvents (MDEA) by Pal and Banat (2015) (17) and the copper adsorption by S. Moulay et al. (2013) (18). ...
... Also, the shape and the mechanical rigidity of the adsorbent promote the separation procedure at the end of the adsorption experience. Various studies have investigated the PAAM hydrogel as a heavy metals adsorbent, such as the removal of mercury ions from aqueous solutions by Ramadan et al. (2010) (16); the removal of chromium ions from industrial lean methyl diethanolamine solvents (MDEA) by Pal and Banat (2015) (17) and the copper adsorption by S. Moulay et al. (2013) (18). ...
The present study focuses on the effect of experimental parameters (pH, temperature, gel mass, metal concentration, contact time) on the performance of lead adsorption by polyacrylamide hydrogels. The results obtained showed that the retention of Pb2+ ions is closely linked to these parameters. The adsorbent gels equilibrate with the metal solution after 180 minutes, and the maximum adsorption capacity is 442.31 mg/g. In addition, the adsorption obeys the pseudo-second-order kinetics and Langmuir isotherm. Desorption of the micropollutant retained by the hydrogel was also studied using 0.1 M of HCl solution. The desorption was rapid, and the efficiency exceeded 90% after a contact time of 90 minutes.
... Several efforts have been made to develop technologies to reclaim alkanolamines from HSSs and overcome the challenges faced by gas industry. The most prominent among these techniques are distillation (Millard and Beasley, 1993), electro-dialysis (Wang et al., 2018;Meng et al., 2008;Alnaimat et al., 2018) ion-exchange techniques (Coberly et al., 1998;Keller et al., 1992), and adsorption (Pal et al., 2013;Pal and Banat, 2015). However, economic considerations limit the wide scale application of most of these processes. ...
... However, selection of a particular technology depends on the type of amine and degradation products, its ability to reclaim, operational and maintenance cost and whether or not it can be easily coupled with the existing plants with little or no modification. Currently techniques such as vacuum distillation (Millard and Beasley, 1993), elctrodialysis (Wang et al., 2018;Meng et al., 2008;Alnaimat et al., 2018), ion exchange techniques (Coberly et al., 1998;Keller et al., 1992) and adsorption process (Pal et al., 2013;Pal and Banat, 2015) are used for the removal of degraded products from lean MDEA. Table 3 provides the comparison of the existing technologies used for the removal of HSS degraded products along with their future research scopes. ...
Heat Stable Salts (HSS) are undesirable contaminates that are generated due to the degradation of the amine solvent. This study deals with the development of a new process for the removal of HSS from amine solvent using magnetic calcium alginate hydrogel composites. The magnetic calcium alginate hydrogel composites was prepared by encapsulating freshly prepared maghemite nanoparticles (γ-Fe 2 O 3) synthesized using a conventional precipitation technique in the calcium alginate beads. The developed magnetic hydrogel composites (CA-Fe 2 O 3) characterized by XRD, SEM and FTIR showed that γ-Fe 2 O 3 are retained homogeneously in the composites matrix. Kinetic and equilibrium batch adsorption experiments revealed that maximum HSS removal of 29.24% was achieved in 240 min with 3.0 g of onto CAFe 2 O 3 composites at 25 °C and sorption efficiency increased with an increase in temperature. Adsorption kinetic study was performed using three kinetic models and the pseudo-second order kinetics very well correlated with the experimental data; demonstrating the chemisorption and endothermic nature of sorption. The reusability experiments showed no significant loss in absorption capability even after eight cycles. Additionally, the superparamagnetic behavior showcased by the magnetic composites allowed easy separation of the composites from lean MDEA using an external magnet. Therefore, such magnetic alginate-Fe 2 O 3 hydrogel composites can work as a simple and cost-effective adsorbent for the reclamation of industrial lean MDEA, with the additional advantages of good efficiency, eco-friendliness and being easy to fabricate and recover.
... Sepiolite is one of the easily available low cost clay is being used as adsorbent for long for the removal of metal ions from solutions [29]. In our previous studies, removal of heavy metal ions like iron and chromium from MDEA solutions using polyacrylamide hydrogel (PAAM) was explored [30]. Though good removal was achieved, the polymeric PAAM adsorbents did not show good mechanical strength urged for more useful alternatives. ...
... While, PAAM hydrogel prepared using ethanol gave the lowest iron removal (14.21 %) and subsequently minimum uptake capacity (2.013µg/g). PAAM hydrogel prepared using water was found to be best for the removal of iron (24.75 % having uptake capacity 3.286 µg/g) from lean MDEA [30]. Therefore, it was used further to prepare composite hydrogel for the adsorption of iron from lean MDEA solvent. ...
... In preparing a high-strength hydrogel for adsorption of metal ions from industrial lean solvents and reusability, a series of PAM hydrogel beads was successfully synthesized by using three components with different functions (Pal and Banat 2015). To fabricate these hydrogel beads, acrylamide as a monomer was polymerized with ammonium peroxodisulphate as initiator. ...
... Other studies have demonstrated that the adsorption of pollutants by hydrogels also can take place by several other mechanisms: hydrogen bonding (Al-Mubaddel et al. 2015;Pal and Banat 2015), coordination bonds (Yang et al. 2010), chelating interaction (Gogoi et al. 2015;Yu et al. 2015a), or a combination of interactions, such as ion exchange/electrostatic interaction (Jin and Bai 2002;Liu et al. 2017;Mirabedini et al. 2017;Yu et al. 2015b), chelating/electrostatic interaction , ion-exchange/chelating interaction (Zheng et al. 2010;Zhou et al. 2012), electrostatic interaction/chelation (Jiang and Liu 2014;Zhang et al. 2016;Zhao and Mitomo 2008), or electrostatic/ hydrophobic interaction (Li 2010;Peng et al. 2016). ...
During the last decade, hydrogels have been used as potential adsorbents for removal of contaminants from aqueous solution. To improve the adsorption efficiency, there are numerous different particles that can be chosen to encapsulate into hydrogels and each particle has their respective advantages. Depending on the type of pollutants and approaching method, the particles will be used to prepare hydrogels. The hydrogels commonly applied in water/wastewater treatment was mainly classified into three classes according to their shape included hydrogel beads, hydrogel films, and hydrogel nanocomposites. In review of many recently research papers, we take a closer look at hydrogels and their applications for removal of contaminants, such as heavy metal ion, dyes, and radionuclides from water/wastewater in order to elucidate the reactions between contaminants and particles and potential for recycling and regeneration of the post-treatment hydrogels.
Graphical abstractᅟ
... These methods are classified as biological, chemical, or physical processes. Adsorption is considered to be the cheapest, easiest, and most effective method [5]. The principle of adsorption treatment is the trapping of pollutants by a material called adsorbent. ...
Hydrogels have been of great interest for the removal of hazardous chemicals and dyes from aqueous media. This study deals with the application of anionic polyacrylamide hydrogels in the removal of cationic dye, crystal violet, from aqueous solutions. Batch adsorption studies presented that the maximum adsorption capacity of dye was found to be 378 mg/g at the initial concentration of 300 mg/L, pH = 5, T = 298 K and 0.039 g of the adsorbent. By analyzing the adsorption mechanism of dye, the kinetic data of dye adsorption fit well with the pseudo-second-order model. The adsorption capability at different equilibrium concentrations follows the Langmuir model, indicating the favorability and feasibility of dye adsorption. The thermodynamic parameters indicate that the adsorption process is spontaneous and endothermic. Density functional theory (DFT), molecular dynamic (MD), and Monte-Carlo simulation studies were applied to support the experimental study.
... Additionally, the operational conditions, advantages, disadvantages and HSS removal efficiency is also briefly discussed. A maximum of 21.36 % and 24.26 % of HSS removal has been achieved by using calcium alginate-Fe 2 O 3 (Edathil et al., 2019) and polyacrylamide hydrogels (Pal and Banat, 2015) through adsorption process, respectively. In one previous report, Meng et al. (Meng et al., 2008) claimed the HSS separation efficiency of 90 % through electrodialysis (ED) technique with the power consumption of 0.31 Wh/L by using anion and cation exchange membranes. ...
The accumulation of heat-stable salts (HSS) in the gas sweetening amine units causes several problems, including foaming, corrosion, and fouling. Herein, a simple and efficient electromagnetic salt removal (EMSR) process was proposed for the separation of HSS from industrial lean amine solution. In this process, HSS were separated through an electro polarization mechanism instead of electrosorption. For this purpose, a lab-scale concentric flow setup was fabricated using aluminum conduit and rod as an anode and cathode, respectively. The effects of the process operational parameters, including flow rate, applied voltage, residence time, and pH were investigated. At the best-operating conditions, a maximum of 15 % HSS removal percentage was achieved in one pass having the power consumption of 0.003 Wh/L. This study demonstrated the potential usage of EMSR for industrial applications.
... The concentration of MB solution was analyzed using UV-Vis spectrophotometer at an incident wavelength of 665 nm. The percentage removal of dye is calculated using the following equation (Pal and Banat 2015): ...
The present research is focused on the synthesis of copper–silver bimetallic nanoparticles using the extracts from the date palm tree (Phoenix dactylifera) leaves. The effect of operational parameters such as type of solvent, pH of the plant extract, salt concentration, and the solution temperature on the particle size and yield of the resultant nanoparticles is reported for the first time. Water–ethanol mixture of 1:1 (v/v) ratio was found to be the best solvent for the extraction of phenolic compounds from the leaves. The novelty of this work lies in the fact that the addition of capping reagent extracted by the green synthesis process from aqueous Sidr leaves reduced the average particle size of the nanoparticles to 26 nm. The characterizations of the copper–silver bimetallic nanoparticles were performed using particle size analyzer, scanning electron microscopy, energy-dispersive X-ray, and X-ray diffraction analysis. Thus, the synthesis of bimetallic copper–silver nanoparticle using palm leaves extract would provide the associated process chemistry. Produced bimetallic nanoparticles were used to establish their catalytic activity to degrade the methylene blue dye from aqueous solution. Well diffusion studies using the as-produced nanoparticles on Bacillus subtilis (Gram-positive) and Escherichia coli (Gram-negative) exhibited the antibacterial ability of the copper–silver bimetallic nanoparticles. The potential catalytic activity for dye degradation and antibacterial assay using nanoparticles highlights the efficacy of the palm leaves and its components.
Graphic abstract
Open image in new window
... Few attempts are reported in literature for the removal of HSS degradation product and heavy metal ions from contaminated amine solutions utilizing services of neutralization [5], vacuum distillation [6], electro dialysis [7][8][9], ionexchange [10,11], and adsorption [12][13][14]. Among these, adsorption using solid sorbents have drawn significant interest owing to their high removal efficiency, ability to remove even traces of contaminants and low operation, installation and regeneration cost. ...
Heat stable salts such as total organic acids (TOA) and heavy metals are well known contaminants in the acid gas removal systems operating using alkanolamines such as methyldiethanolamine (MDEA, 50 wt%). Decontamination of TOA and heavy metals from lean MDEA always remain as a challenge to the gas industry, as accumulation of TOA deteriorates the solvent quality, weakens the absorption capacity and enhances foaming problems leading to huge loss of MDEA and presence of heavy metals results in corrosion and fouling of equipment. Equilibrium batch adsorption were carried out using calcium alginate clay hybrid composites (CAH) containing sepiolite and bentonite for assessing the sorption performance of TOA and heavy metals such as chromium and iron from industrial lean MDEA solutions. The physiochemical properties of the adsorbent were elucidated using SEM, EDX and FTIR analysis. The effects of operational parameters such as amount of sorbent, contact time and temperature on the sorption capacity were also investigated. Kinetics results indicated that the chemisorption nature. The pseudo-second order model gave the best fit. The adsorption efficiency increased with increasing the temperature. Adsorption followed type VI isotherm according to the IUPAC classification, with sorption taking place in different stages. Regeneration studies revealed that 4% CaCl2 acts as an effective eluting agent and no reduction in capacity was observed even after 3 cycles of regeneration. Foaming studies carried out with treated lean MDEA confirmed the reduction in foam of MDEA solutions owing to the effective removal of foam creators such as TOA from lean MDEA by CAH composites. A 15.8% reduction in TOA content was found to decrease the foam height by 37.5%. Thus, CAH composites containing bentonite and sepiolite are having the potential to reclaim industrial lean MDEA solutions.
... In our previous work, we attempted to remove heavy metal ions such as iron and chromium from MDEA solutions using chitosan coated resin/sand and polyacrylamide hydrogel. [4,10] Though good removal was achieved, the polymeric adsorbents being costly with elaborate preparation procedure urged for cheaper lowcost alternatives. ...
Sepiolite clay was used as an adsorbent for the removal of iron ions from industrial methyldiethanolamine (MDEA) solvent. The raw sepiolite clay was modified by different chemical and thermal treatments, and was characterized by FTIR, XRD, SEM-EDX and BET specific surface area analysis. Treating sepiolite with nitric acid significantly improved the adsorption capacity of iron ions from lean MDEA. The experimental equilibrium data were represented by Henry, Freundlich and Langmuir isotherm models. The thermodynamic parameters indicated that the adsorption of iron ions on sepiolite was spontaneous and endothermic process. The kinetic studies showed that the adsorption followed pseudo-second order model.
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.
The technical feasibility of removing heat stable salts (HSS) such as total organic acids (TOA) from industrial lean methyldiethanolamine (MDEA) solutions using calcium alginate/clay hybrid (CAH) composite adsorbent in a continuous fixed bed adsorber has been investigated. The effect of process parameters such as bed diameter, bed height, feed flow rate, and flow direction on breakthrough time, adsorption capacity, and exhaustion time of the fixed-bed sorption system was analyzed. Experimental results showed that higher bed diameter and height, lower flow rate along with up-flow column mode resulted in increased uptake capacity and breakthrough time. Progressive reduction in adsorption capacity from 3.6 mg/g to 2.83 mg/g after three adsorption/desorption cycles using 4.0 wt. % CaCl2 confirmed the practicability of the adsorbent. Simulation of breakthrough curves using general reaction rate models such as Bohart-Adams and Yoon-Nelson yielded a high correlation coefficient (R2 > 0.93), and thus validating the applicability of these models to predict the break through curves under various operating conditions. Furthermore, foaming experiments confirmed the vital role of CAH composite in reducing the foamability of lean MDEA solutions through the synergistic effect of successive biosorption and robustness of the saturated composites to multiple in-situ regeneration using CaCl2.
Alginate based clay hybrid composites were used as adsorbents for the removal of total organic acid anions (TOA) as heat stable salt (HSS) and heavy metal ions (chromium and iron) from industrial lean methyldiethanolamine (MDEA, 50 wt%) solvents. Spherical calcium alginate based hybrid (CAH) composites were prepared using three different filler clays such as sepiolite, montmorillonite and bentonite. To overcome the inherent iron leaching problem associated with clay minerals, an appropriate clay treatment method was utilized before preparing the hydrogel composite. The structure of the clay (before and after modification) and composites was characterized by XRD, whereas the sorption mechanism of the CAH hydrogel composites was conferred in combination with the results obtained from SEM, EDX and FTIR analyses. The effect of quantitative contributions of polymer, bead size, agitation speed, cross linker concentration, reaction time and filler weight% were studied using batch adsorption. The initial experiments confirmed that all the hybrid composites could superiorly separate HSS and heavy metal ions from lean MDEA solvents. 2.0 wt% clay containing composite hydrogels prepared by using 1 mm dropper in a CaCl2 solution of 1.5 M was found to have highest adsorption capacity. Thus, calcium alginate hybrid (CAH) composites showed efficient adsorption capacity for removing all the contaminants present in lean MDEA.
Experiments were carried out to evaluate the batch adsorption of phenol from petroleum refinery wastewater on a locally prepared date-pit activated carbon (DP-AC). Adsorption equilibrium and kinetics data were determined for the uptake of phenol from real refinery wastewater and from synthetically prepared aqueous phenol solution. The data were fitted to several adsorption isotherm and kinetics models. Sips as well as Langmuir models gave the best fit for equilibrium isotherms, whereas the kinetics data were best fitted by the pseudo-second order model. The enthalpy of adsorption showed an exothermic nature of the adsorption process. Several chemical and thermal techniques were tested for the regeneration of saturated activated carbon; using ethanol was found to be the most effective with more than 86% regeneration efficiency after four regeneration cycles.
Modified crosslinked polyacrylamides having different functional groups were prepared by Mannich reaction using different amine compounds such as ethylenediamine (EDA), diethylenetriamine (DETA) and triethylenetetramine (TETA) and sulfomethylation reaction. Products were characterized by determination of their basic group content (BGC), hydroxymethyl group content (HMG), equilibrium degree of swelling (EDS) and FT-IR spectra. For Mannich reactions, BGC and EDS changed with amount of employed amine compounds, reaction time and temperature. Sulfomethylation reactions gave products with high BGC and very high EDS. FT-IR spectroscopic analysis confirmed that a parallel hydrolysis reaction occurred along with the expected modification reactions. The products were used for removal of Cu(II), Cd(II) and Pb(II) ion under competitive and non-competitive conditions at different pH. The metal ion removal capacities changed depending their BGC and EDS. While the Mannich products were selective towards Cu(II) ion, the sulfomethylation products were highly selective to Pb(II) ions. The polymers were used several times by regeneration without loss of adsorption capacity and changing of selectivity properties.
A new kind of attapulgite clay@carbon (ATP@C) nanocomposite adsorbent has been synthesized by a one-pot hydrothermal carbonization process under mild conditions using two cheap, ecofriendly materials (i.e., attapulgite clay (ATP), which is a magnesium aluminum silicate that is abundant in nature, and glucose, which is a green chemical obtained from biomass). Compared to carbon-based materials, this new ATP@C nanocomposite exhibits a high adsorption ability for Cr(VI) and Pb(II) ions with maximum adsorption capacities of 177.74 and 263.83 mg·g(-1), respectively. The results demonstrate that this nanocomposite is an exceptionally promising candidate as a low-cost, sustainable, and effective adsorbent for the removal of toxic ions from water.
The adsorption of copper(II), zinc(II), nickel(II), lead(II), and cadmium(II) on Amberlite IR-120 synthetic sulfonated resin has been studied at different pH and temperatures by batch process. The effects of parameters such as amount of resin, resin contact time, pH, and temperature on the ion exchange separation have been investigated. For the determination of the adsorption behavior of the resin, the adsorption isotherms of metal ions have also been studied. The concentrations of metal ions have been measured by batch techniques and with AAS analysis. Adsorption analysis results obtained at various concentrations showed that the adsorption pattern on the resin followed Freundlich isotherms. Here we report the method that is applied for the sorption/separation of some toxic metals from their solutions.
Several semi-interpenetrating network (Semi-IPN) hydrogels were synthesized by free radical copolymerization of acrylamide, hydroxyethyl methacrylate and N'N'-methylene bis acrylamide crosslinker (MBA) in presence of starch. These hydrogels were characterized by FTIR, DTA-TGA, XRD and SEM. The hydrogel showing the highest swelling% in water was used for removal of low (2.5-40 mg/L) and high (200-500 mg/L) concentration range of malachite green and methyl violet dyes from water. The hydrogel showed high adsorption for both of these dyes. Isotherms, kinetics, mass transfer coefficients and thermodynamics of dye adsorption were also studied.
This study has been carried out to investigate the foaming behavior of aqueous Methyldiethanolamine (MDEA) in presence of different degradation products and other contaminants as additives. This foaming study was combined with physical characterization of the tested solution to enhance the understanding of the foaming behavior. The foaming tendency of aqueous MDEA solution was reported in terms of foam volume. Foam stability was reported on the basis of the time required for the last bubble to break. The effect of degradation products and heavy and light dissolved organics on solution physical properties i.e. density, surface tension and viscosity were studied. The addition of 2.5 wt% of propionic acid decreased the foam volume by about 4% and the foam stability by about 7.14%, while the heaver organic acids (C5–C7) increased foaming. All organic acids increased the solution viscosity and density and decreased the solution surface tension by various extents. Formaldehyde increased the foaming tendency and enhanced the stability of the foam on MDEA solution. Iron(II) sulfide increased the foaming tendency by about 39.7%, although it decreased the foam stability by about 95.6%. The addition of both pentane and heptane decreased the foaming tendency and stability of the 50 wt% MDEA solution. Finally, a mathematical model was proposed to understand the parametric effects behind the foaming problem of aqueous MDEA solutions and to facilitate the tracking of the sources of foaming and alleviate them or reduce their impact.
A systematic method was employed to synthesize several hydrogels by crosslink copolymerization of acrylamide (AM), hydroxyl ethylmethacrylate (HEMA) and N,N’-methylenebisacrylamide (NMBA) at varied operating conditions. Composite hydrogels were also prepared by in situ incorporation of varied amounts of sodium aluminosilicate filler to the monomer mixtures at optimum operating conditions. These hydrogels were used for removal of rhodamine B and methyl violet dye from water at low (0.5–3 mg/L) and high concentration (50–500 mg/L) ranges. The composite hydrogels showed much higher dye adsorption than the unfilled hydrogels. Kinetic, adsorption and thermodynamic parameters for dye adsorption were also evaluated.
Response surface methodology (RSM) based on a three-level, three-variable, Box–Behnken design (BBD) was used to optimize the preparation parameters of a hydrogel consisted of polyvinyl alcohol (PVA), acrylic acid (AA) and tourmaline (Tm). With the adsorption capacity for ammonium ion (NH4+) as the response, the effects of three variables, i.e. neutralization degree (ND) of AA, ratio of PVA to AA, and ratio of Tm to AA, were investigated. The predicted appropriate preparation conditions for the hydrogel were ND of AA of 70%, PVA:AA of 0.0833 and Tm:AA of 0.5, under which a hydrogel was prepared and used as the adsorbent to remove NH4+. The effects of contact time, ion strength, NH4+ concentration, temperature, and pH value on the adsorption capacity were investigated using a batch experiment. The results indicated that the as-prepared hydrogel showed entangled three-dimensional network and had the advantages of fast adsorption rate and high adsorption capacity for NH4+ in a pH range from 3.0 to 8.0. The regeneration and reusable experiments were also performed, and it was observed that the as-prepared hydrogel was stable and regenerable using strong acid (HCl) or base (NaOH) as the desorbing agents.
The heat stable salts (HSS) generated from the gas desulfurization using N-methyldiethanolamine (MDEA) solvents caused many problems such as solution froth, corrosion and fouling of the equipment. In this paper, a specially designed electrodialysis (ED) was employed to remove the heat stable salts from industrial aqueous MDEA solutions. The heat stable salts were successfully removed by adjusting the arrangement of cation- and anion-exchange membranes. To ensure a stable and durative desalination process, appropriate operation parameters such as applied potential and the flow rate were selected as voltage; 9V and flow rate; 40L/h. The experimental results show that about 90% of HSS were removed from aqueous solutions of MDEA solvents while the loss ratio is less than 9% under the appropriate conditions.
A novel technique based on the chronoamperometric measurements was developed to study the sol–gel transition for the solution free radical cross-linking co-polymerization of acrylamide and N, N′-methylene bisacrylamide. The gels were synthesized electrochemically at room temperature in the presence of an initiator, ammonium persulfate. No chemical activator was used for accelerating the reaction; instead a direct voltage was applied by means of a silver-working electrode placed in the reaction mixture. It is found that the current measured during the gelation process monitors the change in the concentration of radicals, which are free to move in the reacting sample. The current due to these free radicals measures the weight average degree of polymerization and gel fraction around the gel point. Observations around the gel point, for low polymerization voltages, show that the gel fraction exponent β and the weight average degree of polymerization exponent γ agree with the mean-field results for low acrylamide concentrations. The samples synthesized above a certain voltage do not show self-similarity at the critical point. This is due to the increase in the local density, so does the heterogeneity, of the gel around the silver electrode, therefore, they do not obey the scaling behavior near the critical point.
A comprehensive coupon corrosion testing program was undertaken to address the effect of various heat stable salts on methyldiethanolamine (MDEA) corrosivity to carbon steel and various stainless steels. Corrosion rates of carbon steel, 304SS, 316SS and 410SS liquid and vapor coupons towards MDEA, and MDEA containing various anions, at 180°F and 250°F, were measured in a reactor. Corrosion results of two refinery plant solutions before and after caustic neutralization were also performed. Based on these results, guidelines were determined for heat stable amine salt levels of oxalates, sulfates, formates and thiosulfates. In addition, caustic neutralization guidelines for MDEA heat stable salts were determined. The results include MDEA corrosivity with succinates, malonates, glycolates, SO2 and ammonia.
Silica gel (G) and amino functionalized silica gel with three different loading of an aminopropyl group viz. 0.51, 1.01, and 1.45 mmol/g, (GN1, GN2, and GN3) were synthesized, characterized, and used as adsorbents for the adsorption of Cu2+ ions from aqueous solution. The specific surface area, pore volume, and BJH pore size of silica gel decreased with an increase in the loading of aminopropyl groups. Kinetic of adsorption of Cu2+ on GN2 followed pseudosecond order. Adsorption isotherms of Cu2+ on functionalized silica samples were best fit by the Sips model for all the three functionalized silica gels, among the four models used to describe the Cu2+ adsorption isotherms. The monolayer copper adsorption capacity for the gel GN1 (0.515 mmol Cu2+/g) and GN2 (0.55 mmol Cu2+/g) were found to be almost similar even when the loading of the amino group increased from 0.51 to 1.01 mmol/g. The NH2/Cu mole ratio was found to be around 1 and 2 for GN1 and GN2, respectively. In the case of GN3 (1.45 mmol NH2/g), the monolayer capacity was found to be 1.05 mmol Cu2+/g with a NH2/Cu mole ratio of 1.38. This study indicates that the population density of NH2 determines the NH2/Cu2+ ratio at saturation of Cu2+ on the functionalized silica gel and the affinity of the gel for the Cu2+.
The adsorption characteristics of cadmium ions from aqueous solutions onto two organo-ceramic adsorbents synthesized in our laboratories were studied. The main species participating in the adsorption process, determined from the chemical equilibrium, is Cd2+. Formation of a bidentate cadmium−thiol complex is proposed to explain the experimental isotherms. The kinetics of adsorption onto the sol−gel-synthesized adsorbent was studied in a differential batch reactor with recycle. Two kinetic models were tested with experimental data: chemical reaction and film/pore mass-transfer resistances. The results indicate that either model can be used to explain the adsorption process as observed from the AARD values and from the F-test. The values of fitted parameters are k1 = 0.0021 L·g/mmol2·min, Dp = 1.4 × 10-7 cm2/s, and τ = 5.0. The last two parameters can be used to satisfactorily predict the breakthrough curve in a fixed bed by the film/pore diffusion model. A sensitivity analysis shows that pore diffusion resistances control the adsorption process.
A novel poly(acrylic acid)/attapulgite superabsorbent composite was synthesized by graft copolymerization reaction of acrylic acid (AA) on attapulgite micropowder using N,N′-methylenebisacrylamide (MBA) as a crosslinker and ammonium persulfate (APS) as an initiator in aqueous solution. The effects on water absorbency of such factors as reaction temperature, initial monomer concentration, degree of neutralization of AA, amount of crosslinker, initiator, and attapulgite were investigated. These crosslinked superabsorbent composites were characterized by thermogravimetetric analysis and scanning electron microscopy. The graft copolymerization reaction of AA on attapulgite micropowder was characterized by FTIR. The water absorbencies for these superabsorbent composites in water and saline solutions were investigated and water-retention tests were carried out. Results obtained from this study show that the water absorbency of the superabsorbent composite synthesized under optimal synthesis conditions with an attapulgite content of 10% exhibited an absorption of 1017 g H2O/g sample and 77 g H2O/g sample in distilled water and in 0.9 wt % NaCl solution, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1596–1603, 2004
In this paper, a novel method was proposed to synthesize ionic liquids by using a specially designed four-compartment configuration electrodialyzer. 1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4), used as a model ionic liquid, was successfully synthesized and concentrated. The products of [BMIM]BF4 could be easily obtained by using the permselectivity of ion-exchange membranes and the migration of ions under dc electric field. The structure of the products was identified with Fourier transform spectra (FTIR) and 1H NMR. It was noted that 92% yield ratio could be achieved while the purity was over 95% after operating 1 h under the voltage of 10 V.
Preparation of crosslinked copolymer beads based on glycidyl methacrylate (GMA), 2-hydroxyethyl methacrylate (HEMA), and divinyl
benzene for the use of heavy metal adsorption has been investigated. In our study, a series of porous copolymer beads were
synthesized by suspension polymerization in the presence of porogens, 1-dodecanol, toluene, and heptane at different dilutions.
The effect of the porogens on the surface appearance and the porous structure of copolymer beads was studied by scanning electron
microscopy and BET method. Diethylene triamine chelating copolymers were obtained through a reaction between amine groups
of diethylene triamine and epoxide pendant groups of GMA. Adsorption isotherm and quantitative analysis for adsorption capacity
involving copper, chromium, manganese, cadmium, iron, and zinc ions were investigated using atomic absorption spectrophotometer.
The adsorption was a function of types of metal ions, adsorption time, and solution properties including pH and metal concentration.
Adsorption equilibrium was achieved in approximately 50min with a maximum adsorption capacity at pH 5.0. The Langmuir isotherm
was found to be well fitted on the adsorption behavior. The maximum metal adsorption capacities in single ion solution in
mole basis were in the order Cu(II)>Cr(VI)>Mn(II)>Zn(II)>Cd (II)>Fe(II). It was found that introducing porogen in
the polymerization mixture produced the copolymer beads with better adsorption capacity. The maximum Cu(II) adsorption capacity
of chelating poly(GMA-co-HEMA) beads were 1.35mmol/g (85.79mg/g) measured from the beads prepared in the presence of 1-heptane with 50% dilution.
Consecutive adsorption–desorption experiments showed that crosslinked poly(GMA-co-HEMA) micro-beads can be reused almost without any change in the adsorption capacity.
Selective absorption of H2S from N2 streams containing H2S and CO2 into aqueous solutions of 2-amino-2-methyl-1-propanol (AMP) as well as N-methyldiethanolamine (MDEA) was investigated in a 2.81×10−2 m o.d. stainless steel wetted-wall column at atmospheric pressure and constant feed gas ratio. In the range of gas flow rates studied (90–180×10−6 m3/s), the effect of gas-phase resistance on the absorption of H2S was significant. The rates of absorption of H2S and the selectivity factor decreased with the contact time for both alkanolamine solutions. With increasing amine concentration in the range 2.0–3.0 kmol/m3, the rates of absorption of both CO2 and H2S increased, but relatively more for CO2, resulting in a consequent decrease in the selectivity factor. In the temperature range 293–313 K, the rates of absorption of CO2 increased marginally with the increase in temperature while the rates of absorption of H2S and the selectivity factor decreased. The maximum selectivity observed in this work was 17.57 and 23.02 for AMP and MDEA, respectively. The acid gas mass transfer has been modelled using equilibrium-mass-transfer-kinetics-based combined model for CO2 and gas-phase transport equation-based approximate model for H2S considering negligible interaction between CO2 and H2S in the liquid phase. The experimental and model results have been found to be in good agreement.
Poly(N,N-dimethylacrylamide-co-sodium acrylate) hydrogel, which bears negatively charged –COO− groups was used to extract organic or inorganic solutes from water. Some model dyes and metal ions have been studied. Cationic dyes are strongly adsorbed and retained by the polymer while adsorbance of hydrophobic dyes was very low and that of anionic dyes was negligible. Both maximum adsorption and equilibrium binding constant varied from one cationic species to the other depending on the chemical structure of the dye, the presence of functional chemical groups and the hydrophobic–hydrophilic balance. In the case of metal cations, adsorption depended on valence. The hydrogel can be regenerated in an aqueous phase of low pH and thus be reused in several adsorption procedures.
The paper presents a study of zinc adsorption using the experimental data on bed sediments of River Hindon in western Uttar Pradesh (India). The effect of various operating variables, viz., initial concentration, solution pH, sediment dose, contact time, and particle size, have been studied. The optimum contact time needed to reach equilibrium was of the order of 60 min and was independent of initial concentration of zinc ions. The extent of adsorption increased with an increase of pH. Furthermore the adsorption of zinc increases with increasing adsorbent doses and decreases with the adsorbent particle size. The content of iron, manganese and organic matter in various fraction of sediment decreases with increasing particle size indicating the possibility of the two geochemical phases to act as the active support material for the adsorption of zinc ions. The adsorption data follows both Langmuir and Freundlich adsorption models. Isotherms were used to determine thermodynamic parameters, viz., free energy change, enthalpy change and entropy change. The negative values of free energy change indicate spontaneous nature of the adsorption while positive values of enthalpy change suggest the endothermic nature of the adsorption of zinc on bed sediment of the River Hindon. The positive values of entropy change indicate randomness at the solid/solution interface.
Hydrogels are commonly studied for tissue engineering applications and controlled drug delivery. In order to evaluate their reliability as scaffolds and delivery devices, literature describes many release studies performed involving different analytical techniques. However, these experiments can be expensive, time-consuming, and often not reproducible. In this study, two injectable agar-carbomer-based hydrogels were studied, both being loaded with sodium fluorescein, a harmless fluorophore with a steric hindrance similar to many small drugs, such as for example steroids and other neuroprotecting agents. Starting from simple, traditional, and inexpensive release experiments, it was possible to indirectly estimate the self-diffusion coefficient (D) of loaded sodium fluorescein. Such a parameter was also directly measured in the gel matrix by means of high resolution magic angle spinning (HRMAS) diffusion-ordered spectroscopy NMR. Because of the agreement between the calculated values and those measured by HRMAS-NMR spectroscopy, the latter approach can be considered as a simple and fast alternative to long analytic procedures.
Polyacrylonitrile (PAN) nanofiber mats were prepared by electrospinning and they were further modified to contain amidino diethylenediamine chelating groups on their surface via heterogeneous reaction with diethylenetriamine (DETA). The obtained aminated PAN (APAN) nanofiber mats were evaluated for their chelating property with four types of metal ions, namely Cu(II), Ag(I), Fe(II), and Pb(II) ions. The amounts of the metal ions adsorbed onto the APAN nanofiber mats were influenced by the initial pH and the initial concentration of the metal ion solutions. Increasing the contact time also resulted in a monotonous increase in the adsorbed amounts of the metal ions, which finally reached equilibria at about 10 h for Cu(II) ions and about 5 h for Ag(I), Fe(II), and Pb(II) ions. The maximal adsorption capacities of the metal ions on the APAN nanofiber mats, as calculated from the Langmuir model, were 150.6, 155.5, 116.5, and 60.6 mg g(-1), respectively. Lastly, the spent APAN nanofiber mats could be facilely regenerated with a hydrochloric acid (HCl) aqueous solution.
The graft copolymerization of ethyl acrylate (EA) onto natural wool fibers initiated by potassium persulphate and Mohr's salt redox initiator system in limited aqueous medium was carried out in heterogeneous media. Ester groups of the grafted copolymers were partially converted into hydrazide function groups followed by hydrazone formation through reaction with isatin. Also the application of the modified fibers for metal ion uptake was studied using Cu(II), Hg(II) and Ni(II). The modified chelating fibers were characterized using FTIR spectroscopy, SEM and X-ray diffraction.
Adsorption capacity of Cu(2+) from aqueous solution onto H(3)PO(4) activated carbon using rubber wood sawdust (RSAC) was investigated in a batch system. Kinetic and isotherm studies were carried out, the thermodynamic parameters like standard Gibb's free energy (Delta G degrees), enthalpy (Delta H degrees) and entropy (DeltaS degrees) were evaluated. The pseudo-second-order model was found to explain the kinetics of Cu(2+) adsorption most effectively. The process optimization was performed through Central Composite Rotary Design using response surface methodology (RSM) by Design Expert Version 5.0.7 (STAT-EASE Inc., Minneapolis, USA). An initial concentration of 35 mg L(-1), temperature of 26 degrees C, carbon loading of 0.45 g(100mL)(-1), adsorption time 208 min and pH of 6.5 was found to be the optimum conditions for the maximum uptake of copper ions of 5.6 mg g(-1) in batch mode.
The coagulation-flocculation process incorporated with membrane separation technology will become a new approach for palm oil mill effluent (POME) treatment as well as water reclamation and reuse. In our current research, a membrane pilot plant has been used for POME treatment where the coagulation-flocculation process plays an important role as a pretreatment process for the mitigation of membrane fouling problems. The pretreated POME with low turbidity values and high water recovery are the main objectives to be achieved through the coagulation-flocculation process. Therefore, treatment optimization to serve these purposes was performed using jar tests and applying a response surface methodology (RSM) to the results. A 2(3) full-factorial central composite design (CCD) was chosen to explain the effect and interaction of three factors: coagulant dosage, flocculent dosage, and pH. The CCD is successfully demonstrated to efficiently determine the optimized parameters, where 78% of water recovery with a 20 NTU turbidity value can be obtained at the optimum value of coagulant dosage, flocculent dosage, and pH at 15 000 mg/L, 300 mg/L, and 6, respectively.
The environmental and health effects of the contamination of soils by heavy metals depend on the ability of the soils to immobilize these contaminants. In this work, the adsorption and desorption of Cu and Zn in the surface layers of 27 acid soils were studied. Adsorption of Cu(II) from 157-3148 mumol L(-1) solutions was much greater than adsorption of Zn(II) from solutions at the same concentration. For both Cu and Zn, the adsorption data were fitted better by the Freundlich equation than by the Langmuir equation. Multiple regression analyses suggest that Cu and Zn adsorption depends to a significant extent on pH and CEC: for both metals these variables accounted for more than 80% of the variance in the Freundlich pre-exponential parameter K(F), and pH also accounted for 57% of the variance in 1/n for Zn and, together with carbon content, for 41% of the variance in 1/n for Cu. The percentage of adsorbed metal susceptible to desorption into 0.01 M NaNO3 was greater for Zn than for Cu, but in both cases depended significantly on pH, decreasing as pH increased. In turn, both pH(H2O) and pH(KCl) are significantly correlated with cation exchange capacity. Desorption of metal adsorbed from solutions at relatively low concentration (787 mumol L(-1)) exhibited power-law dependence on Kd, the quotient expressing distribution between soil and soil solution in the corresponding adsorption experiment, decreasing as increasing Kd reflected increasing affinity of the soil for the metal. The absence of a similarly clear relationship when metal had been adsorbed from solutions at relatively high concentration (2361 mumol L(-1)) is attributed to the scant between-soil variability of Kd at these higher concentrations. In general, adsorption was greater and subsequent desorption less in cultivated soils than in woodland soils.
- A Li
- A Wang
- J Chen
Li, A., Wang, A. and Chen, J. (2004) J. Appl. Polym. Sci. 92, 1596.
- L F Chen
- H W Liang
- Y Lu
- C H Cui
- S H Yu
Chen, L.F., Liang, H.W., Lu, Y., Cui, C.H. and Yu, S.H. (2011) Langmuir 27, 8998.
- P Pal
- F Banat
- A Alshoaibi
Pal, P., Banat, F. and Alshoaibi, A. (2013) J. Nat. Gas Sci. Eng. 15, 14.
- A Demirbas
- E Pehlivan
- F Gode
- T Altun
- G Arslan
Demirbas, A., Pehlivan, E., Gode, F., Altun, T. and Arslan, G. (2005) J. Colloid Interface Sci. 282, 20.
- I Langmuir
Langmuir, I. (1916) J. Am. Chem. Soc. 40, 1361.
- M Monier
- D M Ayad
- A A Sarhan
Monier, M., Ayad, D.M. and Sarhan, A.A. (2010) J. Hazard. Mater. 176, 348.
Colloids Surf. A. 312, 214
- V Bekiari
- M Sotiropoulou
- G Bokias
- P Lianos
- R Bhattacharyya
- S K Ray
- R Bhattacharyya
- S K Ray
- B Mandal
Bekiari, V., Sotiropoulou, M., Bokias, G. and Lianos, P. (2008) Colloids Surf. A. 312, 214.
Bhattacharyya, R. and Ray, S.K. (2014) J. Ind. Eng. Chem. 20, 3714.
Bhattacharyya, R., Ray, S.K. and Mandal, B. (2013) J. Ind. Eng. Chem. 19, 1191.
- M Hong
- Z Shuang
- L Chunxi
- L Liangshi
Hong, M., Shuang, Z., Chunxi, L. and Liangshi, L. (2008) J. Membr. Sci. 322, 436.
- H Meng
- H Li
- C X Li
Meng, H., Li, H. and Li, C.X. (2008) J. Membr. Sci. 318, 1.
- K M Helen
- R Iyyaswami
- G P Magesh
- R M Lima
Helen, K.M., Iyyaswami, R., Magesh, G.P. and Lima, R.M. (2009) Colloids Surf. B. 70, 35.
- T Trakulsujaritchok
- N Noiphom
- N Tangtreamjitmun
- R Saeeng
Trakulsujaritchok, T., Noiphom, N., Tangtreamjitmun, N. and Saeeng, R. (2011) J. Mater. Sci. 46, 5350.
Yıldız, G. and Yılmaz, Y. (2005) Polymer. 46, 12532.
- T Trakulsujaritchok
- N Noiphom
- N Tangtreamjitmun
- R Saeeng
- G Yıldız
- Y Yılmaz
Trakulsujaritchok, T., Noiphom, N., Tangtreamjitmun, N. and Saeeng, R. (2011) J. Mater. Sci. 46, 5350.
Yıldız, G. and Yılmaz, Y. (2005) Polymer. 46, 12532.
- E Alhseinat
- P Pal
- M Keewan
- F Banat
Alhseinat, E., Pal, P., Keewan, M. and Banat, F. (2014) J. Nat. Gas Sci. Eng. 17, 49.
- M Monier
- D M Ayad
- A A Sarhan
- A Alshoaibi
Monier, M., Ayad, D.M. and Sarhan, A.A. (2010) J. Hazard. Mater. 176, 348.
Pal, P., Banat, F. and Alshoaibi, A. (2013) J. Nat. Gas Sci. Eng. 15, 14.
- S Lagergren
Lagergren, S. (1998) K. Sven. Vetenskapsakad. Handl. 24, 1.
- A Demirbas
- E Pehlivan
- F Gode
- T Altun
- G Arslan
Demirbas, A., Pehlivan, E., Gode, F., Altun, T. and Arslan, G. (2005) J. Colloid Interface Sci. 282, 20.
El-Naas, M.H., Al-Zuhair, S. and Alhaija, M.A. (2010) Chem. Eng. J. 162, 997.
Freundlich, H.M. (1906) J. Phys. Chem. 57, 385.
- H Kasgoz
- S Ozgumus
- M Orbay
Kasgoz, H., Ozgumus, S. and Orbay, M. (2003) Polymer. 44, 1785.
- A L Ahmad
- S Ismail
- S Bhatia
- E Alhseinat
- P Pal
- M Keewan
- F Banat
Ahmad, A.L., Ismail, S. and Bhatia, S. (2005) Environ. Sci. Technol. 39, 2828.
Alhseinat, E., Pal, P., Keewan, M. and Banat, F. (2014) J. Nat. Gas Sci. Eng. 17, 49.
- A Demirbas
- E Pehlivan
- F Gode
- T Altun
- G Arslan
- M H El-Naas
- S Al-Zuhair
- M A Alhaija
- H M Freundlich
- S Gomez-Salazar
- J S Lee
- J C Heydweiller
- L L S Tavlarides
- K M Helen
- R Iyyaswami
- G P Magesh
- R M Lima
- M Hong
- Z Shuang
- L Chunxi
- L Liangshi
- H Kasgoz
- S Ozgumus
- M Orbay
Demirbas, A., Pehlivan, E., Gode, F., Altun, T. and Arslan, G. (2005) J. Colloid Interface Sci. 282, 20.
El-Naas, M.H., Al-Zuhair, S. and Alhaija, M.A. (2010) Chem. Eng. J. 162, 997.
Freundlich, H.M. (1906) J. Phys. Chem. 57, 385.
Gomez-Salazar, S., Lee, J.S., Heydweiller, J.C. and Tavlarides, L.L.S. (2003) Ind. Eng. Chem. Res. 42, 3403.
Helen, K.M., Iyyaswami, R., Magesh, G.P. and Lima, R.M. (2009) Colloids Surf. B. 70, 35.
Hong, M., Shuang, Z., Chunxi, L. and Liangshi, L. (2008) J. Membr. Sci. 322, 436.
Jain, C.K., Singhal, D.C. and Sharma, M.K. (2004) J. Hazard. Mater. B114, 231.
Kampalanonwat, P. and Supaphol, P. (2010) ACS Appl. Mater. Interfaces. 2, 3619.
Kasgoz, H., Ozgumus, S. and Orbay, M. (2003) Polymer. 44, 1785.
Lagergren, S. (1998) K. Sven. Vetenskapsakad. Handl. 24, 1.
Langmuir, I. (1916) J. Am. Chem. Soc. 40, 1361.
- T Trakulsujaritchok
- N Noiphom
- N Tangtreamjitmun
- R Saeeng
- G Yıldız
- Y Yılmaz
- Y Zheng
- Y Liu
- A Wang
Trakulsujaritchok, T., Noiphom, N., Tangtreamjitmun, N. and Saeeng, R. (2011) J. Mater. Sci. 46, 5350.
Yıldız, G. and Yılmaz, Y. (2005) Polymer. 46, 12532.
Zheng, Y., Liu, Y. and Wang, A. (2011) Chem. Eng. J. 171, 1201.