Adsorption of some heavy metal ions from aqueous solutions on Nafion 117 membrane

Nafion 117 membrane was investigated for the removal of Ni(II), Co(II), Pb(II), Cu(II) and Ag(I) metal ions from their synthesized aqueous solutions. The different variables affecting the adsorption capacity of the membrane such as contact time, initial metal ion concentration in the feed solution, pH of the sorption medium and temperature of the solution were investigated on a batch sorption basis. The affinity of Nafion 117 membrane towards heavy metal ions was found to increase in the sequence of Cu(II), Ni(II), Co(II), Pb(II), and Ag(I) with adsorption equilibrium achieved after 30 min for all metal ions. Among all parameters, pH has the most significant effect on the adsorption capacity, particularly in the range of 3.1-5.9. The variation of temperature in the range of 25-65 °C was found to have no significant effect on the adsorption capacity. Nafion 117 membrane was found to have high stability combined with repeated regeneration ability and can be suggested for effective removal of heavy metal ions such as Cu(II), Ni(II) and Co(II) from aqueous solutions.     

Studies on syntheses and properties of chelating resins based on chitosan

Chelating resins have some good adsorption properties for some metal ions, especially for several noble metal ions. Thus to retrieve rare metals using chelating resins is always an interesting project for chemistry researchers. In this study we synthesized a series of chelating resins based on chitosan and investigated adsorbing capacities, adsorption rates, and adsorption selectivities for Ag(I), Au(III), Pd(II), Pt(IV), Cu(II), Hg(II), and Zn(II). The results indicate that the resins have remarkable adsorbing capacities and adsorption rates for four noble metal ions and Hg(II). For instance, one of the resins adsorbs Au(III) and the adsorbing capacity is up to 7.11 mmol/g. However, the adsorbing capacities of the resins for Cu(II) and Zn(II) are much less than for the noble metal ions. Finally, x-ray photoelectron spectroscopy studies of a chelating resin and its metal chelates were made. The result reveals that the basis of the chelations is a chemical process. © 1996 John Wiley & Sons, Inc.     

Separation and Recovery of Silver(I) Ions from Base Metal Ions by Thiourea- or Urea-Formaldehyde Chelating Resin

Abstract

In the present work, thiourea-formaldehyde (TF) and urea-formaldehyde (UF) chelating resins have been synthesized and they have been used in the adsorptions of Ag(I), Cu(II), and Zn(II) metal ions by batch and column methods. The effect of initial acidity of Ag(I) solution and the adsorption capacities of TF and UF resins by batch method and the separation of Ag(I) ions from Cu(II) and Zn(II) base metal ions by the column method were examined experimentally. The adsorption capacities of TF and UF resins were found as 58.14 and 47.39 mg Ag(I)/g by batch method and 30.7 and 4.66 mg Ag(I)/g, 0.80 and 0.121 mg Cu(II)/g, and under 0.002 mg Zn(II)/g by the column method, respectively. It was found that Ag(I) ions showed higher affinity towards TF resin than UF resin, compared with Cu(II) or Zn(II) ions, and Ag(I) could be separated more effectively by TF resin from Cu(II)and Zn(II) ions.     

Thiouracil modified activated carbon as a sorbent for some precious and heavy metal ions

A new sorbent is prepared by modifying activated carbon obtained from apricot stones with 2-hydroxy-2-mercaptopyrimidine (2-thiouracil). The products have been characterized as to their surface area, pore volumes, content of the functional groups with basic and acidic properties, IR spectra, sulfur content. Their sorption properties with respect to some precious (Au(III), Ag(I), Pt(II)) and heavy (Cu(II), Mn(II), Ni(II), Hg(II)) metals are investigated. The sorption is studied as a function of pH (in the interval 1÷8) and stirring time (1÷24 h). The static sorption capacities towards the metal ions are determined under optimum conditions at room temperature. The new sorbent containing thiouracil is appropriate for simultaneous preconcentration of the precious and heavy metal ions within a wide pH range. It shows a significantly higher capacity for the investigated metal ions than the original carbon.     

Equilibrium and kinetic studies on the removal of some metal ions using biogenic amorphous silica

In the present study agricultural waste (rice husks) was used for the production of biogenic silica. The resulting material was obtained by incineration of rice husks at a temperature of 800°С and was characterized by means of XRD, FTIR, SEM-EDS, Hg-porosimetry and N₂-adsorption. The adsorption ability of the rice husks ash towards Fe(III), Pb(II), Cr(III) and Cu(II) ions in single- and multi-component aqueous solutions was studied in a batch system. The effects of contact time, acidity of initial solutions and metal ion concentrations were followed. Different models were used to determine the adsorption mechanism. Equilibrium experimental data were fitted to linear Langmuir and Freundlich models. The maximum adsorption capacities for single- and multi-component adsorption were calculated.     

Competitive adsorption of Ag (I) and Cu (II) by tripolyphosphate crosslinked chitosan beads

Alkalization of chitosan before crosslinking was applied in this study to enhance the adsorption capacity of the modified chitosan. Competitive adsorption of Ag (I) and Cu (II) from bimetallic solutions was studied using the newly synthesized tripolyphosphate crosslinked alkalized chitosan beads. Results indicated that alkalization before crosslinking helps to protect amine group from crosslinking and hence increases the uptake capacity and selectively of the synthesized beads toward Ag (I). The maximum uptakes of Ag (I) and Cu (II) were 82.9 and 15.5 mg g^?1, respectively, at room temperature with an initial concentration of each metal being 2.0 mM and the sorbent dosage of 1.0 g L^?1. The uptake of Ag (I) and Cu (II) by the beads can be better described by Langmuir isotherm and pseudo‐second rate equation. Analyses from FTIR and XPS confirmed that free amine, hydroxyl, and groups are involved in metal binding with amine and hydroxyl groups more selective to Ag (I). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42717.     

Cysteine-metal affinity chromatography: determination of heavy metal adsorption properties

Various adsorbent materials have been reported in the literature for heavy metal removal. We have developed a novel approach to obtain high metal sorption capacity utilising cysteine containing adsorbent. Metal complexing aminoacid-ligand cysteine was immobilised onto poly(hydroxyethylmethacrylate) (PHEMA) microbeads. PHEMA-cysteine affinity microbeads containing 0.318 mmol cysteine/g were used in the removal of heavy metal ions (i.e. copper, lead and cadmium) from aqueous media containing different amounts of these ions (50–400 mg/l for Pb(II) and Cd(II), 25–60 mg/l for Cu(II)) and at different pH values (4.0–7.0). The maximum adsorption capacity of heavy metal ions onto the cysteine-containing microbeads under non-competitive conditions were 0.259 mmol/g for Pb(II), 0.330 mmol/g for Cd(II) and 0.229 mmol/g for Cu(II). The affinity order was observed as follows: Cd(II)>Pb(II)>Cu(II). The competitive adsorption capacities of the heavy metals were 0.260 mmol/g for Cd(II) and 0.120 mmol/g for Cu(II). Pb(II) adsorption onto cysteine-immobilised microbeads was zero under competitive conditions. The affinity order was as follows: Cd(II)>Cu(II)>Pb(II). The formation constants of cysteine–metal ion complexes have been investigated applying the method of Ruzic. The calculated value of stability constants were 1.75×10⁴ l/mol for Pb(II)–cysteine complex and 4.35×10⁴ l/mol for Cd(II)–cysteine complex and 1.39×10⁴ l/mol for Cu(II)–cysteine complex. PHEMA microbeads carrying cysteine can be regenerated by washing with a solution of hydrochloric acid (0.05 M). The maximum desorption ratio was greater than 99%. These PHEMA microbeads are suitable for repeated use for more than three adsorption–desorption cycles without considerable loss in adsorption capacity.     

Metal sorption on macroporous poly(GMA-co-EGDMA) modified with ethylene diamine

Two samples of macroporous crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate), poly(GMA-co-EGDMA), with different porosity parameters were synthesized by suspension copolymerization and modified by ring-opening reaction of the pendant epoxy groups with ethylene diamine (EDA). The samples were characterized by mercury porosimetry, FT-IR spectroscopy and elemental analysis. The sorption rate of the modified copolymer, poly(GMA-co-EGDMA)-en for Cu(II) ions determined under non-competitive conditions was relatively rapid, i.e. the maximum capacity was reached within 30 min. Batch sorption capacities for Cu(II), Fe(II), Mn(II), Cd(II), Zn(II), Pb(II), Cr(III) and Pt(IV) ions were determined under non-competitive conditions in the pH range 1.25–5.5 at room temperature. The maximum sorption capacities of poly(GMA-co-EGDMA)-en under non-competitive conditions were 1.30 mmol/g for Pt(IV) at pH 5.5, 1.10 mmol/g for Cu(II) at pH 5.5, 1.06 mmol/g for Pb(II) at pH 1.25 and 0.67 mmol/g for Cd(II) ions at pH 5.5. The selectivity of poly(GMA-co-EGDMA)-en towards Cu(II), Co(II), Ni(II), Pb(II) and Pt(IV) ions was investigated under competitive conditions. Poly(GMA-co-EGDMA)-en showed high selectivity for Pt(IV) over Cu(II), Co(II), Ni(II) and Pb(II) ions at pH 2.1. At pH 5.5, the metal sorption capacities of poly(GMA-co-EGDMA)-en decreased in the order: Cu(II) > Co(II) > Pt(IV) ≈ Ni(II) > Pb(II). Regeneration of the Cu(II), Ni(II) and Pb(II) loaded poly(GMA-co-EGDMA)-en with 2 M H₂SO₄ showed that the polymer can be reused in several sorption/desorption cycles.     

Sorption studies of heavy metal ions on pectin-nano-titanium dioxide composite adsorbent

The Cu(II), Cd(II), Zn(II), and Pb(II) sorption kinetics and equilibrium on hybrid material, composed of pectin and titanium dioxide nanopowder, were examined. Parameters, such as pH and adsorbent dose, were also investigated. The experimental data were better described by the Langmuir model. The maximum adsorption capacities were 1.37, 0.68, 0.51, and 0.83 mmol/g for Cu(II), Cd(II), Zn(II), and Pb(II), respectively. The introduction of nano-TiO₂ improved the kinetics of the metal ion sorption. The titanium dioxide, despite its small content (6%), contributes to the removal of the examined metal ions and eventually to the adsorption capacity of hybrid beads.     

Removal of metal ions in aqueous solutions by organic polymers: use of a polydiphenylamine resin

Adsorption of Ni(II), Cu(II), Zn(II), Pb(II) and Cd(II) ions on a polydiphenylamine resin prepared at a strongly oxidizing controlled potential of 3.2 V (vs. ECS) was studied in aqueous solutions. The optimum sorption conditions were determined. The optimum pH for the removal of metal ions was between 4 and 6 for Ni(II), 6 for Cu(II) and Pb(II) and 5 for Zn(II) and Cd(II). The total sorption capacity of the resin was 57.3 mg g⁻¹ for Ni(II), 23 mg g⁻¹ for Cu(II), 36.9 mg g⁻¹ for Zn(II), 19 mg g⁻¹ for Pb(II) and 24.5 mg g⁻¹ for Cd(II). The sorption capacity was compared with other conventional chelating polymers. The sorption kinetics was fairly rapid, as apparent from the loading half time (t_1/2) values, indicating a better accessibility of the chelating sites. The study of the selectivity of the metal ions in the binary solutions shows that the resin presents a higher affinity for the ions of nickel (II).     

Removal of copper(II) from an aqueous solution with copper(II)‐imprinted chitosan microspheres

Ion‐imprinted chitosan (CS) microspheres (MIPs) were prepared with Cu(II) as a template and epichlorohydrin as a crosslinker for the selective separation of Cu(II) from aqueous solution. The microspheres showed a higher adsorption capacity and selectivity for the Cu(II) ions than nonimprinted chitosan microspheres (NMIPs) without a template. The results show that the adsorption of Cu(II) on the CS microspheres was affected by the initial pH value, initial Cu(II) concentration, and temperature. The kinetic parameters of the adsorption process indicated that the adsorption followed a second‐order adsorption process. Equilibrium experiments showed very good fits with the Langmuir isotherm equation for the monolayer adsorption process. The maximum sorption capacity calculated from the Langmuir isotherm was 201.66 mg/g for the Cu–MIPs and 189.51 mg/g for the NMIPs; these values were close to the experimental ones. The selectivity coefficients of Cu(II) and other metal ions on the NMIPs indicated a preference for Cu(II). © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of Sulfonamide Containing Cellulose Based Sorbent for Removal of Mercury Ions

A new sulfonamide containing cellulose based sorbent was prepared in three steps; poly (acrylonitrile) (PAN) grafting onto cellulose by redox polymerization method, amination of PAN grafted cellulose with ethylenediamine, and sulfamidation with benzene sulfonyl chloride. The resulting polymeric sorbent, which had a sulfonamide content of 3.4 mmol/g, was effective for the removal of mercury ions from aqueous solutions. The mercury sorption capacity of the sorbent is around 1.95 mmol/g under non-buffered conditions. The experiments performed under identical conditions with some metal ions reveal that Cd(II), Mg (II), Zn(II), and Fe(III) ions are also extractable in low quantity (0.02–0.46 mmol/g). The sorbed mercury can be eluted by repeated treatment with hot acetic acid.     

Synthesis of 1,4,8,11‐tetraazacyclotetradecane monomer by addition of acryloyl chloride and its polymer for specific transition metal binding

1,4,8,11‐Tetraazacyclotetradecane (cyclam) was reacted with acryloyl chloride in a 1 : 2 molar ratio in dichloromethane in the presence of pyridine at 0°C. The modified cyclam was polymerized by adding an azobisisobutyronitrile initiator and irradiated with a UV lamp under reflux for 6 h. Precipitated cyclam containing polymer in the bulk structure was removed from the suspension by filtration. After washing and drying the final polymeric materials were used for transition metal ion adsorption and desorption studies. A Fourier transform IR spectrophotometer and thermogravimetric analyzer were used to characterize the polymeric structure. The affinity of the polymeric material for transition metal ions was used to test the adsorption–desorption of selected ions [Cu(II), Ni(II), Co(II), Cd(II), Pb(II)] from aqueous media containing different amounts of these metal ions (5–800 ppm) at different pH values (2.0–8.0). It was found that the adsorption rates were high and the adsorption equilibrium was reached in about 30 min. The uptake of the transition metal ions onto the polymer from solutions containing a single metal ion was 3.17 mmol/g for Cu(II), 0.98 mmol/g for Cd(II), 0.79 mmol/g for Co(II), 0.78 mmol/g for Ni(II), and 0.32 mmol/g for Pb(II). This polymer showed high affinity for Cu(II) compared to the other metal ions in the single ion solution and in the mixture of transition metal ions. The affinity order of the transition metal ions was Cu(II) ? Ni(II) > Cd(II) > Co(II) > Pb(II) for competitive adsorption. More than 95% of the adsorbed transition metal ions were desorbed in 2 h in a desorption medium containing 1.0M HNO₃. Poly(cyclam) was found to be suitable for repeated use of more than five cycles without a noticeable loss of adsorption capacity. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1406–1414, 2002     

Separation and preconcentration of some heavy‐metal ions using new chelating polymeric hydrogels

Two new chelating polymeric hydrogels, crosslinked polyacrylamide/triethylenetetraamine/CS₂Na (hydrogel I) and crosslinked polyacrylamide/diethylenetriamine/CS₂Na (hydrogel II), were prepared by the transamidation and dithiocarbamylation of crosslinked polyacrylamide. The products were characterized with elemental analysis and IR spectroscopy. In both polymeric hydrogels, the optimum pH for the removal of Cd(II), Pb(II), and Zn(II) ions ranged from 7 to 8, from 6 to 7, and from 7 to 8, respectively. The sorption isotherms of the investigated metal ions on the prepared hydrogels were developed, and the equilibrium data fitted the Langmuir and Freundlich isotherm models well. At the optimum pH for each metal ion, the maximum sorption capacities of hydrogel I toward Cd(II), Pb(II), and Zn(II) ions, estimated from the Langmuir model, were 5.3, 0.63, and 1.27 mmol/g, respectively, and those of hydrogel II were 4.1, 0.59, and 0.89 mmol/g, respectively. The experimental sorption capacities of hydrogel I toward Cd(II), Pb(II), and Zn(II) ions were 4.5, 0.6, and 1.2 mmol/g, respectively. In the case of hydrogel II, the capacities were 3.7, 0.52, and 0.88 mmol/g in the same prescribed order. The thermodynamic parameters (the free energy of sorption, enthalpy change, and entropy change) for cadmium, lead, and zinc sorption on the prepared polymers were also determined from the temperature dependence. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Metal ion sorption by chitosan–tripolyphosphate beads

Heavy metal removal from wastewater is crucial for the proper management of discharged water from mining operations. This residual water is typically unusable for other purposes such as for human/animal, crop, or industrial consumption. Eco‐friendly adsorption materials are necessary to ensure the sustainable treatment of this wastewater. Therefore, the sorption of Cu(II), Cd(II), Pb(II), and Zn(II) ions onto chitosan–tripolyphosphate (CTPP) beads was investigated using real mining wastewater and prepared ion metal solutions. The effects of pH, contact time, temperature, selectivity, and maximum sorption capacity in successive batches at different concentrations were studied. The optimum sorption of cations, except for copper (pH 3) was found at pH 5. Equilibrium in the adsorption of all metals was reached at 24 h of contact. Studies of the maximum sorption capacity at different concentrations showed that the CTPP beads could adsorb 158, 55, 47, and 47 mg/g of Pb(II), Cu(II), Cd(II), and Zn(II), respectively. Experimental data for the sorption of Pb(II) were optimally correlated with the Langmuir model. The thermodynamic parameters such as the changes in enthalpy (ΔH⁰), entropy (ΔS⁰), and free energy (ΔG⁰) were determined. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45511.     

羧甲基甲壳胺纤维对铜离子的吸附性能

为了提高甲壳胺纤维对重金属离子的吸附性能,用氯乙酸对纤维进行改性处理,在纤维的结构中引入羧甲基团后使纤维同时具有能结合重金属离子的胺基和羧酸基团。研究了改性后纤维在不同的改性程度、添加量、时间、温度、pH值等条件下对铜离子的吸附性能。结果表明:羧甲基化改性后的甲壳胺纤维对铜离子有很好的吸附性能。在同样的条件下,未改性的纤维对铜离子的吸附值为41.3mg/g,而改性后的纤维为79.4mg/g。经过羧甲基化改性的甲壳胺纤维对铜离子的饱和吸附容量可以达到148.1mg/g。     

Chelating polymer-based membranes. Preparation and use for metal ion scavenging and sorption of murine immunoglobulin G by immobilized Ni(II) ions

Copolymers of 2-(2-hydroxyethoxy)ethyl methacrylate and ethylene dimethacrylate in the form of homogeneous membrane sheets were modified by chelating groups of iminodiacetic acid (IDA) in a two step reaction. The obtained sorbents showed high chelating capacity for Ni(II), Cu(II) and Fe(III) ions (up to 1.3 mmol/g). The potential use of immobilized Ni(II)-IDA complexes for sorption of murine immunoglobulin G by the immobilized metal affinity (IMA) method was tested. The sorption behaviour was characterized by a Langmuir-Freundlich adsorption isotherm. It was shown that the chelating membranes could be used for the sorption of low amounts of protein.     

Adsorption of Cd(II), Pb(II), and Ag(I) in aqueous solution on hollow chitosan microspheres

Cross‐linked chitosans synthesized by the inverse emulsion cross‐link method were used to investigate adsorption of three metal ions [Cd(II), Pb(II), and Ag(I)] in an aqueous solution. The chitosan microsphere, was characterized by FTIR and SEM, and adsorption of Cd(II), Pb(II), and Ag(I) ions onto a cross‐linked chitosan was examined through analysis of pH, agitation time, temperature, and initial concentration of the metal. The order of adsorption capacity for the three metal ions was Cd²⁺ > Pb²⁺ > Ag⁺. This method showed that adsorption of the three metal ions in an aqueous solution followed the monolayer coverage of the adsorbents through physical adsorption phenomena and coordination because the amino (? NH₂) and/or hydroxy (? OH) groups on chitosan chains serve as coordination sites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mono- and multi-component biosorption of lead(II), cadmium(II), copper(II) and nickel(II) ions onto coco-peat biomass

The potential of using coco-peat biomass (CPB) has been assessed for the removal of Pb(II), Cd(II), Cu(II) and Ni(II) ions from single and quaternary solutions. According to Langmuir isotherm, the maximum biosorption capacity of CPB was 0.484, 0.151, 0.383 and 0.181 mmol/g for Pb(II), Cd(II), Cu(II) and Ni(II) ions, respectively. Scanning electron microscopy along with energy-dispersive X-ray spectroscopy and Fourier-transform IR spectroscopy confirmed changes in the biosorbent functionality after metal sorption. Through quaternary isotherm experiments, 16.1%, 48.2%, 32.3% and 46.5% decrease in experimental uptakes were observed for Pb(II), Cd(II), Cu(II) and Ni(II), respectively, in the presence of other metal ions.     

Adsorption of Cr(VI) on Cross‐Linked Chitosan Beads

Abstract

A possibility of Cr(VI) removal by the adsorption method is discussed in the paper. An adsorbent were hydrogel chitosan beads are produced by the phase inversion method (by changing pH). The possibility of removing Cr(VI) ions by both pure chitosan hydrogel and its chelate compounds (chitosan cross‐linked with Cu(II) and Ag(I) ions) was investigated. The adsorption proceeded from the solutions of potassium dichromate and ammonium dichromate (NH₄)₂Cr₂O₇ and K₂Cr₂O₇. The process rates and adsorption isotherms were determined and described by relevant equations. The process rate was described by the pseudo‐ and second‐order equations, and adsorption equilibria by the Langmuir equations. A slight advantageous change in adsorption properties of chitosan beads was revealed after cross‐linking (for chromium concentration up to 10 g/dm³). A maximum adsorption was 1.1 g_Cr/g chitosan. Results of the studies show that chitosan hydrogel proves useful in the removal of Cr(VI) ions, additionally, cross‐linking with Cu(II) and Ag(I) ions has an advantageous effect in the case of low‐concentrated solutions.