No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Removal of copper, nickel and lead from wastewater using a modified cellulose material: A comparison
Abstract
Heavy metal waste streams from a variety of industrial sources pose a significant
environmental threat to receiving waters. Significant research work has focused
on the use of adsorbents and adsorption in the treatment and recovery of these
metals from waste streams. This paper focuses specifically on the design of a
novel adsorbent based on the naturally occurring material, cellulose and
application of this novel material to the removal of selected heavy metals from
waste streams. Cellulose material has limited heavy metal adsorbing capability.
To enhance its sorption capacity, a sorbent material was prepared by firstly
grafting glycidyl methacrylate monomer to cellulose. The grafted product was
then functionalised by the addition of imidazole. The novel material was then
assessed for its ability to adsorb the heavy metals Cu(II), Ni(II) and Pb(II).
Uptake levels on the cellulose-g-GMA-imidazole material were 68 mg g-1 Cu(II),
45 mg g-1 Ni(II), 71 mg g-1 Pb(II). These uptake levels compared favourably with
those achieved using other naturally occurring materials. The level of uptake of
each metal on the modified cellulose material was found, in all cases, to be
significantly influenced by aqueous pH. The optimum pH range in all cases
ranged from approximately pH 4 to pH 5.5. The speed of uptake of each metal
on the sorbent material ranged from approximately 40 minutes in the case of
Cu(II) and Pb(II) to almost 400 minutes for Ni(II) depending on initial metal
concentration in solution. The overall kinetics in each case is best described by
the pseudo-second order approach. Almost complete recovery of each metal
from the modified cellulose material was possible using a 0.1M acid solution;
however, re-use of the sorbent materials in further adsorption cycles yielded
variable outcomes.
Keywords: wastewater, heavy metals, adsorption, modified cellulose.
... Cellulose is the most rigid and inaccessible polysaccharide in the CW (Harris & Stone, 2009). Despite the abundance of hydroxyl groups in cellulose, raw cellulose has a poor adsorption and binding ability for trace metals (O'Connell et al., 2008;Ge et al., 2016). ...
Cadmium (Cd) accumulation is highly variable among Arabidopsis halleri populations. To identify cell wall (CW) components that contribute to the contrasting Cd accumulation between PL22-H (Cd-hyperaccumulator) and I16-E (Cd-excluder), Cd absorption capacity of CW polysaccharides, CW mono- and poly- saccharides contents and CW glycan profiles were compared between these two populations. PL22-H pectin contained 3-fold higher Cd concentration than I16-E pectin in roots, and (1→4)-β-galactan pectic epitope showed the biggest difference between PL22-H and I16-E. CW-related differentially expressed genes (DEGs) between PL22-H and I16-E were identified and corresponding A. thaliana mutants were phenotyped for Cd tolerance and accumulation. A higher Cd translocation was observed in GALACTAN SYNTHASE1 A. thaliana knockout and overexpressor mutants, which both showed a lengthening of the RG-I sidechains after Cd treatment, contrary to the wild-type. Overall, our results support an indirect role for (1→4)-β-galactan in Cd translocation, possibly by a joint effect of regulating the length of RG-I sidechains, the pectin structure and interactions between polysaccharides in the CW. The characterization of other CW-related DEGs between I16-E and PL22-H selected allowed to identify a possible role in Zn translocation for BIIDXI and LEUNIG-HOMOLOG genes, which are both involved in pectin modification.
... Particularly in the case of free radical mechanism, different steps followed by the free radical mechanism for the grafting of cellulose by taking BPO (Benzoyl peroxide as an initiator) (Fig. 3) [10,61]. Table 8 shows the modification of cellulose obtained from different sources as a potential bio sorbent for the removal of various metal ions from the water system [62,[64][65][66][67][68][69][70]. Singha et al. (2014) reported the variation in adsorption capacity due to grafting and demonstrated that there is an enhancement in adsorption capacity after grafting as shown in Fig. 4 [66]. ...
The aim of this study is more towards environmental friendly solutions by transforming the lignocellulosic waste into valuable material which improves and upgrades technology for waste management and minimization. Therefore, the recent advances are based on improvements in the removal of hazardous materials by efficient and low-cost bio-sorbents. Agricultural waste contains a high concentration of cellulose which is a low cost, biodegradable, non-toxic, thermally and mechanically stable which explores the study towards clean and sustainable development. Different types of biomass are taken as adsorbent like leaves, fibers, husk, stem, seeds etc. The present study emphasis a clean and sustainable treatment for the elimination of metal ions from the environment by the management of waste i.e. sugarcane bagasse, rice husk, coconut husk etc. Various adsorption parameters have been examined at optimized conditions such as temperature, the dosage of adsorbent, contact/agitation time, pH, flow rate, bed height and concentration of dye or metal ions. Spectrophotometric techniques are used for the evaluation of the concentration of metal ions before and after sorption. This review summarizes many modifying agents and grafting techniques for the elimination of metal ions which improves the adsorption capacity. The present study compiles the grafting on the backbone of cellulose. This review recapitulates the different routes of extraction and modification of cellulose. The properties of biosorbent will be enhanced by several modification techniques but out of all these grafting is considered as the most effective one is shown in this study. This review also summarizes the various grafting methods with free radical grafting mechanism. This review also compiles the studies based on modified and unmodified biosorbents for the comparison of sorption capacities with and without modification. The chemically modified cellulosic biomass is mostly preferred than unmodified one due to more adsorption efficiency favored by a maximum number of reactive binding sites, enhanced ion-exchange properties and availability of more functional groups after modification.
... The amount of heavy metals released into the aqueous environment has been increasing as a result of anthropogenic activities such as mining, sludge disposal, and electroplating, with the effects of these metals on the ecosystem causing global concern (Shojaeimehr et al., 2014;Svecova et al., 2006;Wang et al., 2013). Adsorption offers an alternative to the remediation of industrial and municipal wastewater effluent as conventional technologies such as ion exchange, reverse osmosis, filtration, electrochemical treatment, and membrane technologies are expensive and generate large amounts of sludge waste (O'Connell et al., 2008b). The adsorption process is very effective and simple compared to other treatments, especially in removing low concentrations of heavy metals from the water matrix (Ashraf et al., 2011). ...
This study observed the influence of temperature, initial Cu(II) ion concentration, and sorbent dosage on the Cu(II) removal from the water matrix using surface-oxidized cellulose nanowhiskers (CNWs) bearing carboxylate functionalities. In addition, this study focused on the actual conditions in a wastewater treatment plant. Conductometric titration of CNWs suspensions showed a surface charge of 54 and 410 mmol/kg for the unmodified and modified CNWs, respectively, which indicated that the modified CNWs provide a relatively high surface area per unit mass than the unmodified CNWs. In addition, the stability of the modified CNWs was tested under different conditions and proved that the functional groups were permanent and not degraded. Response surface methodology (RSM) and artificial neural network (ANN) models were employed in order to optimize the system and to create a predictive model to evaluate the Cu(II) removal performance of the modified CNWs. The performance of the ANN and RSM models were statistically evaluated in terms of the coefficient of determination (R2), absolute average deviation (AAD), and the root mean squared error (RMSE) on predicted experiment outcomes. Moreover, to confirm the model suitability, unseen experiments were conducted for 14 new trials not belonging to the training data set and located both inside and outside of the training set boundaries. Result showed that the ANN model (R2 = 0.9925, AAD = 1.15%, RMSE = 1.66) outperformed the RSM model (R2 = 0.9541, AAD = 7.07%, RMSE = 3.99) in terms of the R2, AAD, and RMSE when predicting the Cu(II) removal and is thus more reliable. The Langmuir and Freundlich isotherm models were applied to the equilibrium data and the results revealed that Langmuir isotherm (R2 = 0.9998) had better correlation than the Freundlich isotherm (R2 = 0.9461). Experimental data were also tested in terms of kinetics studies using pseudo-first order and pseudo-second order kinetic models. The results showed that the pseudo-second-order model accurately described the kinetics of adsorption.
Cellulose powder was modified with Sodium Hypochlorite (NaOCl) and Octenyl Succinic Anhydride (OSA) in
different proportions. The adsorbents were characterised by BET, FTIR, XRD, TGA and SEM. Intrinsic viscosity
increased with degree of substitution (DS). FTIR peaks confirmed the presence of carbonyl groups. Batch adsorption
parameters studied were contact time, adsorbent dosage, pH and temperature. Adsorption process was
influenced significantly by pH. Freundlich isotherm showed a better correlation coefficient (R2 and χ2) than
Langmuir and Temkin isotherms. The adsorption process was inferred as physico-chemical adsorption process
(based on isotherm and kinetic modelling). Pseudo second order kinetics model was found to fit well on the
empirical data obtained. Adsorption of Cu(II) ions over the modified cellulose was found to be exothermic in
nature (ΔH<0). HCl was found to be more effective desorbing agent than NaOH.
Hydrazinolyzed cellulose-graft-polymethyl acrylate (Cell-g-PMA-HZ), an efficient adsorbent for removal of Cd(II) and Pb(II) from aqueous solution, has been prepared by ceric salt-initiated graft polymerization of methyl acrylate from microcrystalline cellulose surface and subsequent hydrazinolysis. The influences of initial pH, contact time, and temperature on adsorption capacity of Cell-g-PMA-HZ as well as adsorption equilibrium, kinetic and thermodynamic properties were examined in detail. As for Cd(II) adsorption, kinetic adsorption can be explained by pseudo-second-order, while adsorption isotherm fits well with Langmuir isotherm model, from which maximum equilibrium adsorption capacity can be derived as 235.85 mg g⁻¹ at 28°C. Further thermodynamic investigation indicated that adsorption of Cd(II) by adsorbent Cell-g-PMA-HZ is endothermic and spontaneous under studied conditions. On the other hand, isotherm of Pb(II) adsorption fits well with Freundlich isotherm model and is more likely to be a physical-adsorption-dominated process. Consecutive adsorption-desorption experiments showed that Cell-g-PMA-HZ is reusable with satisfactory adsorption capacity.
In hospitals' monitoring rooms for X-ray radiography, there are special windows for doctors to monitor the patient. These special lead glasses are X-ray repelling. Lead is used in the glass batch for X-ray repelling as its atomic radius is high. Recent studies on lead showed that this material is hazardous to both human beings and the environment. In this study, as an innovation trial in the glass production, strontium is used instead of lead in the glass batch. Several glass composition alternatives have been carried out to replace the lead with strontium in the glass batch. The glass samples have been analyzed for X-ray repelling function.
Membranes can be used to remove organic materials of chemical oxygen demand (COD) from wastewater. Eight polymeric membranes (FT30, PVD, DSII, DS, BW30, 37100, 3750 and NF45) were evaluated for COD reduction in wastewater from an alcohol manufacturing plant using reverse osmosis. The flux declined within a short period for all membranes. The best COD removal was achieved using NF45. The NF45 and PVD membranes had the greatest productivity, but neither could reduce the VCOD to a desirable level in a single step.
New legislation such as the Water Framework Directive (WFD) will require Member States to better understand the concentrations and loads of contaminants entering surface waters. This will include inputs from wastewater treatment plants (WWTP) as well as from other urban, industrial and agricultural sources. A review of available literature revealed a shortage of data on the levels and sources of heavy metals entering WWTP from urban sources. As a consequence, the concentrations of heavy metals (cadmium, chromium, copper, mercury, nickel, lead and zinc) were determined in the wastewater from an urban catchment located in the UK, as part of a project undertaken for UK Water Industry Research (UKWIR). Both foul and surface water samples were taken. Metal concentrations varied considerably in the foul water samples, both between sources and over the course of the week. Concentrations of most metals were higher in the Monday town centre samples, attributed to leaching from stagnant water remaining in the pipework of office buildings over the weekend. Runoff concentrations were higher in the light industrial estate samples than in the domestic samples for all the metals, and exhibited highest levels in the 'first flush' samples, coincident with the initial flow of runoff containing the highest concentrations of suspended solids.
Chitosan and Ca-alginate, derivatives of biopolymer, were separately prepared from crab chitin and algin in pellet form for adsorption of Cu(II) and Ni(II) from aqueous solutions. The capability of these biopolymers was also investigated to remove copper and nickel from aqueous solutions in an immobilization system, along with a comparison made of these biopolymers with other adsorbents. Additionally, the feasibility of alginate/chitosan in pellets to remove nickel ion and nickel cyanide complex from polluted water was investigated. Stabilizing chitosan physically in an alginate support medium was deemed possible, by means of which both free metal and metal cyanide ions could be removed from aqueous solutions in an engineering system. However, the crosslinking reaction during immobilization would result in blocking of some adsorption sites.
6-Deoxy-6-mercaptocellulose and its S-substituted derivatives were synthesized from 6-bromo-6-deoxycellulose and their sorption behavior for metal ions was examined. Carboxyl, amino, isothiouronium, mercapto and additional hydroxyl groups were introduced to cellulose. The first two groups were effective for the sorption of many kinds of metal ions. Ag(I) was sorbed strongly by all the derivatives studied. Many derivatives sorbed large amounts of Hg(II). Competitive sorption experiments showed that Ag(I) was sorbed preferentially by most of the cellulose derivatives and that a cellulose derivative having an isothiouronium moiety sorbed Hg(II) in a comparable amount to Ag(I).
The process of electro deposition of heavy metals on bodies of different materials (for instance on non metallic objects to improve their look, their mechanical resistance and other physical properties) generates effluents contaminated by residues of valuable metal salts whose disposal is difficult and expensive. After several months of on site pilot testing it was possible to draw optimised flow schemes and to define the type of membrane more suitable to the recovery of metal salts from highly acidic solutions (pH close to 1) and to the production of high quality, reusable industrial water. The paper describes the various steps of the testing program, the comparison of mathematical models and results of plant operation, the optimised flow diagram of different applications (recovery of copper from the cleaning baths in a copper electro deposition plant, recovery of nickel sulphate and chloride from the cleaning baths in the electro deposition of nickel) and the operating costs and physical features of industrial plants.
An investigation was undertaken regarding the adsorption of lead(II) and copper(II) ions from aqueous solutions by water-insoluble starch graft copolymers containing tertiary amine groups, which were prepared by grafting dimethylaminoethyl methacrylate onto commercial crosslinked starch. The effects of treatment time, initial pH of the solution, metal ion concentration, and grafting percentage of the starch graft copolymers on the adsorption were considered. Two hour of adsorption time was found to be sufficient for reaching the adsorption equilibrium, and the adsorption equilibrium data correlate well with the Langmuir isotherm equation. For the starch graft copolymer with the grafting percentage of 60%, the saturation adsorption capacity evaluated from Langmuir isotherms toward lead(II) and copper(II) ions was found to be 2.09 and 2.12 mmol g−1 (dry weight), respectively.
The ion-exchange equilibrium of Pb(II) and Cd(II) on clinoptilolite from different deposits was studied in this work. The Langmuir isotherm fitted the ion-exchange equilibrium data of both ions better than the Freundlich isotherm. The capacity of the natural zeolite to exchange Cd(II) and Pb(II) increased, augmenting the solution pH. This behaviour was attributed to the interactions between the ions in solution and the surface charge of the zeolite. Moreover, the capacity of the natural zeolite to exchange Cd(II) and Pb(II) was increased when the temperature was raised from 15 to 35 °C. This tendency was explained by assuming that the ion exchange was an endothermic reaction. The selectivity of the zeolite for the metal cations decreased in the following order: Pb(II) > Cd(II). This order was not modified while reducing the solution pH, but the zeolite selectivity was increased. At pH 2 the selectivity of the zeolite for Pb(II) was nearly three times larger than at pH 4. Copyright © 2006 Society of Chemical Industry
Regenerated cellulose wood pulp was grafted with the vinyl monomer glycidyl methacrylate (GMA) using ceric ammonium nitrate as initiator and was further fuctionalised with imidazole to produce a novel adsorbent material, cellulose-g-GMA-imidazole. All cellulose, grafted cellulose and functionalized cellulose grafts were physically and chemically characterized using a number of analytical techniques, including elemental analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis, and scanning electron microscopy. The cellulose-g-GMA material was found to contain 1.75 mmol g−1 epoxy groups. These epoxy groups permitted introduction of metal binding functionality to produce the cellulose-g-GMA-imidazole final product. Following characterization, a series of adsorption studies were carried out on the cellulose-g-GMA-imidazole to assess its capacity in the removal of Cu2+ ions from solution. Cellulose-g-GMA-imidazole sorbent showed an uptake of ∼70 mg g−1 of copper from aqueous solution. The adsorption process is best described by the Langmuir model of adsorption, and the thermodynamics of the process suggest that the binding process is mildly exothermic. The kinetics of the adsorption process indicated that copper uptake occurred within 30 min and that pseudo-second-order kinetics best describe the overall process. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 2006
New materials containing carboxylate groups have been synthesized by grafting polyacrylic acid onto sawdust. These new adsorbents
were subjected to continuous extraction of different metal ions using packed columns to determine their maximum binding capacities.
They exhibit binding capacities 15–40 times higher than unmodified sawdusts for removal of Cu2+, Ni2+, and Cd2+ chosen as representative heavy metal ions. Cation desorption and adsorbent regeneration could be effected by elution with
a diluted HCl solution; water as an eluent has no effect on metal desorption.
Two natural zeolites, clinoptilolite and chabazite, have been evaluated with respect to their selectivity and removal performance for the treatment of effluents con taminated with mixed heavy metals, namely Pb, Cd, Cu, Zn, Cr, Ni and Co. Parameters such as metal concentration, pH and presence of competing ions were examined and removal performance was determined in terms of the zeolites, ion exchange capacity measured at room temperature. The study showed that at metal concentrations ranging from 1 mg l-1 to 10 mg l-1 the zeolites exhibited an optimum removal efficiency at metals concentration of 10 mg l-1. Clinoptilohte and chabazite exhibited different selectivity profiles for all metals studied except for Pb for which both zeolites performed exceptionally well. The selectivity sequences for clinoptilolite and chabazite are summarized as follows: chabazite (Pb>Cd>Zn>Co>Cu>Ni>Cr); and clinoptilolite (Pb>Cu>Cd>Zn>Cr>Co>Ni). The study also showed that the chabazite exchange capacity is superior to that of clinoptilolite which is mainly due to the higher Al substitution of Si which provides chabazite with a negative framework favourable to higher exchange capability. Solution pH was found to have an effect on metal removal as pH can influence both the character of the exchanging ions and the zeolite itself. The metal removal mechanism was demonstrated to be controlled by ion exchange and precipitation was negligible. The results also showed that Ca was a major competing cation for ion exchange for both clinoptilolite and chabazite when concentrations exceeded 1000 mg 1-1. Overall, chabazite and clinoptilolite removal efficiency was not affected by the presence of more than one heavy metal in solution which demonstrates their potential application in the treatment of effluents contaminated with mixed heavy metals.
A series of cross-linked chitosan resins have been synthesized by forming chitosan coordination of Cu(II) as template in dilute acetic acid solutions under microwaves irradiation, then reacting the Cu(II)–chitosan complex with glutaraldehyde as cross-linking agent under microwave irradiation, and finally removing off the Cu(II ) with dilute acid. The adsorption capacity and selectivity of the cross-linked chitosan for Cu2+, Ni2+ and Co2+ have also been investigated. The experimental results show that these resins obtained have better adsorption capacity for Cu2+ than Ni2+ and Co2+, very good stability and reusability in acidic solutions.
The abilities of different species of seaweeds and their derivatives to remove a range of heavy metals from solution under standard laboratory conditions were determined. The three species of brown seaweeds were Ecklonia maxima, Lessonia flavicans and Durvillea potatorum. The two seaweed derivatives produced by commercial seaweed processing were alginate fibres and dealginated seaweed waste. The abilities of these biomasses to sequester the heavy-metal ions copper, nickel, lead, zinc and cadmium from solution under constant agitation were compared. The effect of the presence of more than one metal ion in solution was investigated in order to determine whether any competition effects might have affected metal-ion uptake. The metal-removal capacity of these seaweeds and their derivatives is discussed in the light of the economic and environmental aspects of using such a wastewater-treatment system on an industrial scale.
The chemical contamination of water from a wide range of toxic derivatives, in particular heavy metals, aromatic molecules and dyes, is a serious environmental problem owing to their potential human toxicity. Therefore, there is a need to develop technologies that can remove toxic pollutants found in wastewaters. Among all the treatments proposed, adsorption is one of the more popular methods for the removal of pollutants from the wastewater. Adsorption is a procedure of choice for treating industrial effluents, and a useful tool for protecting the environment. In particular, adsorption on natural polymers and their derivatives are known to remove pollutants from water. The increasing number of publications on adsorption of toxic compounds by modified polysaccharides shows that there is a recent increasing interest in the synthesis of new low-cost adsorbents used in wastewater treatment. The present review shows the recent developments in the synthesis of adsorbents containing polysaccharides, in particular modified biopolymers derived from chitin, chitosan, starch and cyclodextrin. New polysaccharide based-materials are described and their advantages for the removal of pollutants from the wastewater discussed. The main objective of this review is to provide recent information about the most important features of these polymeric materials and to show the advantages gained from the use of adsorbents containing modified biopolymers in waste water treatment.
The adsorption of Cu(II) ions onto chitosan and cross-linked chitosan beads has been investigated. Chitosan beads were cross-linked with glutaraldehyde (GLA), epichlorohydrin (ECH) and ethylene glycol diglycidyl ether (EGDE) in order to obtain sorbents that are insoluble in aqueous acidic and basic solution. Batch adsorption experiments were carried out as a function of pH, agitation period, agitation rate and concentration of Cu(II) ions. A pH of 6.0 was found to be a optimum for Cu(II) adsorption on chitosan and cross-linked chitosan beads. Isotherm studies indicate Cu(II) can be effectively removed by chitosan and cross-linked chitosan beads. Adsorption isothermal data could be well interpreted by the Langmuir equation. Langmuir constants have been determined for chitosan and cross-linked chitosan beads. The experimental data of the adsorption equilibrium from Cu(II) solution correlated well with the Langmuir isotherm equation. The uptakes of Cu(II) ions on chitosan beads were 80.71 mg Cu(II)/g chitosan, on chitosan-GLA beads were 59.67 mg Cu(II)/g chitosan-GLA, on chitosan-ECH beads were 62.47 mg Cu(II)/g chitosan-ECH and on chitosan-EGDE beads were 45.94 mg Cu(II)/g chitosan-EGDE. The Cu(II) ions can be removed from the chitosan and cross-linked chitosan beads rapidly by treatment with an aqueous EDTA solution and at the same time the chitosan and cross-linked chitosan beads can be regenerated and also can be used again to adsorb heavy metal ions.
Metal ions play an important role in biological systems, and without their catalytic presence in trace or ultratrace amounts many essential co-factors for many biochemical reactions would not take place. However, they become toxic to cells when their concentrations surpass certain optimal (natural) levels. Copper is an essential metal. Catalytic copper, because of its mobilization and redox activity, is believed to play a central role in the formation of reactive oxygen species (ROS), such as O2-* and *OH radicals, that bind very fast to DNA, and produce damage by breaking the DNA strands or modifying the bases and/or deoxyribose leading to carcinogenesis. The chemistry and biochemistry of copper is briefly accounted together with its involvement in cancer and other diseases.
The removal of single heavy metals Co and Zn from aqueous solutions using various low-cost adsorbents (Fe(2)O(3), Fe(3)O(4), FeS, steel wool, Mg pellets, Cu pellets, Zn pellets, Al pellets, Fe pellets, coal, and GAC) was investigated. Experiments were performed at different solution pH values (1.5-9) and metal concentrations (0.67-333 mg/l). The effect of solution pH on metal adsorption using Fe(2)O(3) and Fe(3)O(4) was significant, but was negligibly small using steel wool, Mg pellets, Fe pellets, and Al pellets over the entire pH range. Steel wool and Mg pellets were the most excellent adsorbents; for example, the removal of Zn and Co from dilute solutions (<35 mg/l) was greater than 94% at an adsorbent dose of 1.7 g/l. A mass transfer model, which involves two parameters tau (50% breakthrough time) and k (proportionality constant), was proposed to describe breakthrough data of Co in the fixed beds packed with steel wool and Mg pellets. The calculated breakthrough curves agreed well with the measured data (standard deviation < 6%). The value of tau decreased with increasing the flow rate. The effects of flow rates on the value of k and adsorption capacity are discussed.
An uptake of zinc (Zn), copper (Cu), and lead (Pb) from aqueous solutions by ion exchange on natural zeolitic tuff has been studied. The Croatian zeolite clinoptilolite from the Donje Jesenje deposit has been used as a natural ion exchanger. The efficiency of removal is higher for Pb and Cu than for Zn ions. Measured concentrations of Si in the liquid phase identify the detachment of the aluminosilicate structure during ion exchange in the presence of H(+) and OH(-) ions. The adsorption isotherm equations; Langmuir-Freundlich, Redlich-Petersen, Toth, Dubinin-Radushkevich, modified Dubinin-Radushkevich, and Lineweawer-Burk were derived from the basic empirical equations, and used for calculation of ion exchange parameters. The best fitting of experimental results to the proposed isotherms was observed in models that assume that ionic species bind first at energetically most favorable sites, with multi-layer adsorption taking place subsequently.
In the present paper, a study on laboratory scale to perform a treatment for valuable metals recovery from electronic and galvanic industrial wastes, is reported. The characterisation of the waste, performed by XRD, SEM, EDX and chemical analysis, showed a high metals content in the sludge, such as Cu, Ni, Mn, Pb, Sn, W. A leaching process, coupled by electrowinning, is then proposed in order to reduce the volume of the waste material and to recover selectively valuable metals, such as Cu and Ni. During the leaching step, carried out by using H(2)SO(4), several factors were investigated (acid concentration, temperature and time of treatment). The leached liquor has been successfully treated with an electrowinning process, to recover copper and nickel. The copper and nickel depositions, were performed in acid and alkaline conditions, respectively. The Faraday yield was of about 95%. The energy consumption was 2.13 and 4.43 kWh per kg of copper and nickel recovered, respectively. At the end of the process, about 94-99% of the initial content of Cu and Ni was recovered at the cathode. The experimental results obtained, showed the technical feasibility of the process.
The ion exchange equilibrium of Pb(II) on clinoptilolite modified with NH(4)Cl and NaCl can be represented by two types of isotherms. The first one is the ion exchange isotherm based upon the constant of thermodynamic equilibrium for the ion exchange reaction; however, the fitting procedure for this isotherm can be very tedious due to all the calculations involved and additional thermodynamic data. The second one is the Langmuir isotherm. The use of the Langmuir isotherm to represent ion exchange equilibrium has increased in recent last years since it adequately fits the equilibrium data and, furthermore, its calculation is much simpler. A comparison between the two isotherms showed that they fitted the experimental data reasonably well, but the Langmuir isotherm is much simpler and easier to use.
Water Pollution VIII: Modelling, Monitoring and Management
- O ' Connell
- D W Birkinshaw
- C Dwyer
O'Connell, D.W., Birkinshaw, C. & O'Dwyer T.F., Water Pollution VIII:
Modelling, Monitoring and Management., Eds. Brebbia C.A. and Antunes
do Carmo J.S., WIT Press, Southampton, U.K., Section 9, Wastewater
Treatment, pp. 489–498, 2006.
An investigation of adsorption of lead(II) and copper(II) ions by water-insoluble starch graft copolymers
- L M Zhang
- D Q Chen
Zhang, L.M. & Chen, D.Q., An investigation of adsorption of lead(II) and
copper(II) ions by water-insoluble starch graft copolymers. Colloids Surf A
Phys Eng Aspects, 205, pp. 231-236, 2002.
Water Pollution VIII: Modelling, Monitoring and Management
- D W O'connell
- C Birkinshaw
- T F O'dwyer
O'Connell, D.W., Birkinshaw, C. & O'Dwyer T.F., Water Pollution VIII:
Modelling, Monitoring and Management., Eds. Brebbia C.A. and Antunes
do Carmo J.S., WIT Press, Southampton, U.K., Section 9, Wastewater
Treatment, pp. 489-498, 2006.
Decontamination of synthetic solutions containing heavy metals using chemically modified sawdusts bearing polyacrylic acid chains
- M Gaey
- V Marchetti
- A Clement
- B Loubinoux
- P Gerardin
Gaey, M., Marchetti,V., Clement, A., Loubinoux, B. & Gerardin, P.,
Decontamination of synthetic solutions containing heavy metals using
chemically modified sawdusts bearing polyacrylic acid chains. Journal of
Wood Science, 46, pp. 331-333, 2000.