Preparation and characterization of magnetic polymethylmethacrylate microbeads carrying ethylene diamine for removal of Cu(II), Cd(II), Pb(II), and Hg(II) from aqueous solutions

Magnetic polymethylmethacrylate (mPMMA) microbeads carrying ethylene diamine (EDA) were prepared for the removal of heavy metal ions (i.e., copper, lead, cadmium, and mercury) from aqueous solutions containing different amount of these ions (5–700 mg/L) and at different pH values (2.0–8.0). Adsorption of heavy metal ions on the unmodified mPMMA microbeads was very low (3.6 μmol/g for Cu(II), 4.2 μmol/g for Pb(II), 4.6 μmol/g for Cd(II), and 2.9 μmol/g for Hg(II)). EDA‐incorporation significantly increased the heavy metal adsorption (201 μmol/g for Cu(II), 186 μmol/g for Pb(II), 162 μmol/g for Cd(II), and 150 μmol/g for Hg(II)). Competitive adsorption capacities (in the case of adsorption from mixture) were determined to be 79.8 μmol/g for Cu(II), 58.7 μmol/g for Pb(II), 52.4 μmol/g for Cd(II), and 45.3 μmol/g for Hg(II). The observed affinity order in adsorption was found to be Cu(II) > Pb(II) > Cd(II) > Hg(II) for both under noncompetitive and competitive conditions. The adsorption of heavy metal ions increased with increasing pH and reached a plateau value at around pH 5.0. The optimal pH range for heavy‐metal removal was shown to be from 5.0 to 8.0. Desorption of heavy‐metal ions was achieved using 0.1 M HNO₃. The maximum elution value was as high as 98%. These microbeads are suitable for repeated use for more than five adsorption‐desorption cycles without considerable loss of adsorption capacity. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 81–89, 2000     

Synthesis and application of cotton‐based chelate fibers grafted with poly(1‐vinyl‐1,2,4‐triazole) side chains

Cotton‐based chelate fibers grafted with poly(1‐vinyl‐1,2,4‐triazole) (PVTAZ) side chains were synthesized facilely by ozone‐induced graft polymerization of 1‐vinyl‐1,2,4‐triazole (VTAZ) monomer onto cotton fibers. The synthesis conditions were optimized to improve the yield and mechanical strength of the products. The obtained cotton‐g‐PVTAZ fibers were characterized and evaluated for batch adsorption of heavy metal ions from aqueous solutions. The maximum adsorption capacity of Ag(I), Pb(II), and Cu(II) on the fibers at pH 6.8 was 522, 330, and 184 mg/g, respectively. At 30% graft yield, the Young's modulus of cotton fiber increased about 26.5%, and its adsorption capacities of Ag(I), Pb(II), and Cu(II) increased about 2.6, 1.9, and 1.4 times, respectively. After washed with 0.1 mol/L HNO₃ solutions, the adsorbed metal ions were eluted, and the regenerated cotton‐g‐PVTAZ fibers could be used repeatedly for water treatment. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41617.     

Adsorption of heavy‐metal ions on poly(ethylene imine)‐immobilized poly(methyl methacrylate) microspheres

Poly(methyl methacrylate) (PMMA) microspheres carrying poly(ethylene imine) (PEI) were prepared for the removal of heavy‐metal ions (copper, cadmium, and lead) from aqueous solutions with different amounts of these ions (50–600 mg/L) and different pH values (3.0–7.0). Ester groups in the PMMA structures were converted to imine groups in a reaction with PEI as a metal‐chelating ligand in the presence of NaH. The adsorption of heavy‐metal ions on the unmodified PMMA microspheres was very low [3.6 μmol/g for Cu(II), 4.6 μmol/g for Cd(II), and 4.2 μmol/g for Pb(II)]. PEI immobilization significantly increased the heavy‐metal adsorption [0.224 mmol/g for Cu(II), 0.276 mmol/g for Cd(II), and 0.126 mmol/g for Pb(II)]. The affinity order of adsorption (in moles) was Cd(II) > Cu(II) > Pb(II). The adsorption of heavy‐metal ions increased with increasing pH and reached a plateau value around pH 5.5. Their adsorption behavior was approximately described with the Langmuir equation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 197–205, 2001     

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.     

PSSMA修饰磁性氧化石墨烯对Pb2+、Cu2+ 的吸附性能

以氧化石墨烯(GO)、FeCl_3·6H_2O及聚(4-苯乙烯磺酸-共聚-马来酸)钠盐(PSSMA)为主要原料,通过简便一步溶剂热法制备了阴离子聚电解质修饰磁性氧化石墨烯(MGO@PSSMA),并将其用于水溶液中重金属Pb~(2+)、Cu~(2+)的吸附去除。采用FTIR、SEM、TEM、VSM和DLS对制备的MGO@PSSMA进行了表征。考察了溶液pH、吸附时间、溶液初始质量浓度对Pb~(2+)、Cu~(2+)在MGO@PSSMA及未经PSSMA修饰磁性氧化石墨烯(MGO)上吸附的影响。探讨了吸附等温过程、吸附动力学及吸附作用机理。结果表明:MGO表面引入PSSMA可有效增加其对Pb~(2+)、Cu~(2+)的吸附量。在pH=5,溶液初始质量浓度为300 mg/L时,MGO@PSSMA对Pb~(2+)和Cu~(2+)的实际吸附量达141.1和104.8 mg/g。当溶液初始质量浓度为150 mg/L时,MGO@PSSMA对Pb~(2+)和Cu~(2+)的吸附平衡时间分别为2和1.5 min。MGO@PSSMA对Pb~(2+)、Cu~(2+)的吸附动力学及吸附等温数据分别符合准二级吸附动力学模型和Langmuir吸附等温模型。使用乙二胺四乙酸(EDTA)和HCl可实现MGO@PSSMA的有效再生;通过外加磁场作用可实现MGO@PSSMA的回收再利用。     

Metal‐chelating properties of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) membranes

Metal‐chelating membranes have advantages as adsorbents in comparison with conventional beads because they are not compressible and they eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of poly(2‐hydroxyethyl methacrylate–methacryloylamidohistidine) [poly(HEMA–MAH)] membranes for the removal of three toxic heavy‐metal ions—Cd(II), Pb(II), and Hg(II)—from aquatic systems. The poly(HEMA–MAH) membranes were characterized with scanning electron microscopy and ¹H‐NMR spectroscopy. The adsorption capacity of the poly(HEMA–MAH) membranes for the selected heavy‐metal ions from aqueous media containing different amounts of these ions (30–500 mg/L) and at different pH values (3.0–7.0) was investigated. The adsorption capacity of the membranes increased with time during the first 60 min and then leveled off toward the equilibrium adsorption. The maximum amounts of the heavy‐metal ions adsorbed were 8.2, 31.5, and 23.2 mg/g for Cd(II), Pb(II), and Hg(II), respectively. The competitive adsorption of the metal ions was also studied. When the metal ions competed, the adsorbed amounts were 2.9 mg of Cd(II)/g, 14.8 mg of Pb(II)/g, and 9.4 mg of Hg(II)/g. The poly(HEMA–MAH) membranes could be regenerated via washing with a solution of nitric acid (0.01M). The desorption ratio was as high as 97%. These membranes were suitable for repeated use for more than three adsorption/desorption cycles with negligible loss in the adsorption capacity. The stability constants for the metal‐ion/2‐methacryloylamidohistidine complexes were calculated to be 3.47 × 10⁶, 7.75 × 10⁷, and 2.01 × 10⁷ L/mol for Cd(II), Pb(II), and Hg(II) ions, respectively, with the Ruzic method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1213–1219, 2005     

Preparation and Characterization of the Newly Synthesized Metal‐Complexing‐Ligand N‐Methacryloylhistidine Having PHEMA Beads for Heavy Metal Removal from Aqueous Solutions

The aim of this study was to investigate in detail the performance for removal of heavy metal ions of beads composed of poly(2‐hydroxyethyl methacrylate) (pHEMA) to which N‐methacryloylhistidine (MAH) was copolymerized. The metal‐complexing ligand MAH was synthesized by using methacryloyl chloride and histidine. Spherical beads with an average size of 150–200 μm were obtained by the radical suspension polymerization of MAH and HEMA conducted in an aqueous dispersion medium. Owing to the reasonably rough character of the bead surface, p(HEMA‐MAH) beads had a specific surface area of 17.6 m²/g. The synthesized MAH monomer was characterized by NMR; p(HEMA‐MAH) beads were characterized by swelling studies, FTIR and elemental analysis. The p(HEMA‐MAH) beads with a swelling ratio of 65%, and containing 1.6 mmol MAH/g, were used in the adsorption/desorption experiments. Adsorption capacity of the beads for the selected metal ions, i. e., Cu(II), Cd(II), Cr(III), Hg(II) and Pb(II), were investigated in aqueous media containing different amounts of these ions (10–750 mg/L) and at different pH values (3.0–7.0). Adsorption equilibria were established in about 20 min. The maximum adsorption capacities of the p(HEMA‐MAH) beads were 122.7 mg/g for Cu(II), 468.8 mg/g for Cr(III), 639.4 mg/g for Cd(II), 714.1 mg/g for Pb(II) and 1 234.4 mg/g for Hg(II). pH significantly affected the adsorption capacity of MAH incorporated beads. The chelating beads can be easily regenerated by 0.1 M HNO₃ with high effectiveness. These features make p(HEMA‐MAH) beads a potential candidate for heavy metal removal at high capacity.     

Determination of the competitive adsorption of heavy metal ions on poly(n‐vinyl‐2‐pyrrolidone/acrylic acid) hydrogels by differential pulse polarography

Poly(N‐vinyl‐2‐pyrrolidone) and poly(N‐vinyl‐2‐pyrrolidone/acrylic acid) hydrogels were prepared by gamma irradiation for the removal of heavy metal ions (i.e., lead, copper, zinc, and cadmium) from aqueous solutions containing different amounts of these ions (2.5–10 mg/L) and at different pH values (1–13). The observed affinity order in adsorption of these metal ions on the hydrogels was Zn(II) > Pb(II) > Cu(II) > Cd(II) under competitive conditions. The optimal pH range for the heavy metal ions was from 7 to 9. The adsorption of the heavy metal ions decreased with increasing temperature in both water and synthetic seawater conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2013–2018, 2003     

Polarographic determination of the competitive adsorption of U(VI), Pb(II), and Cd(II) ions on poly(N‐vinyl‐2‐pyrrolidone‐g‐citric acid) hydrogels

Poly(N‐vinyl‐2‐pyrrolidone‐g‐citric acid) [P(VP‐g‐CA)] hydrogels were prepared for the removal of U(VI), Pb(II), and Cd(II) from aqueous solutions containing different amounts of these ions (2.5–10 mg/L). Different pHs (1–13), temperatures (20–40°C), and ionic strengths (0.5M) were also tried for the adsorption behavior of these ions. The competitive adsorption values of U(VI), Pb(II), and Cd(II) ions on pure poly(N‐vinyl‐2‐pyrrolidone) were low [0.71–2.03 mg of U(VI)/g of dry gel, 0.15–1.58 mg of Pb(II)/g of dry gel, and 0.10–0.68 mg of Cd(II)/g of dry gel]. The incorporation of citric acid significantly increased the adsorption of these ions [0.67–2.12 mg of U(VI)/g of dry gel, 0.44–1.88 mg of Pb(II)/g of dry gel, and 0.04–0.92 mg of Cd(II)/g of dry gel for P(VP‐g‐CA)‐1; 0.71–2.36 mg of U(VI)/g of dry gel, 0.60–2.16 mg of Pb(II)/g of dry gel, and 0.14–0.80 mg of Cd(II)/g of dry gel for P(VP‐g‐CA)‐2; and 0.79–2.47 mg of U(VI)/g of dry gel, 0.70–2.30 mg of Pb(II)/g of dry gel, and 0.20–0.86 mg of Cd(II)/g of dry gel for P(VP‐g‐CA)‐3]. The observed affinity order of adsorption was U(VI) > Pb(II) > Cd(II) for competitive conditions. The optimal pH range for the removal of these ions was 5–9. Competitive adsorption studies showed that other stimuli, such as the temperature and ionic strength of the solution, also influenced the U(VI), Pb(II), and Cd(II) adsorption capacity of P(VP‐g‐CA) hydrogels. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2019–2024, 2003     

Adsorption characterization of lead(II) and cadmium(II) on crosslinked carboxymethyl starch

The adsorption of Pb(II) and Cd(II) ions with crosslinked carboxymethyl starch (CCS) was investigated as function of the solution pH, contact time, initial metal‐ion concentration, and temperature. Isotherm studies revealed that the adsorption of metal ions onto CCS better followed the Langmuir isotherm and the Dubinin–Radushkevich isotherm with adsorption maximum capacities of about 80.0 and 47.0 mg/g for Pb(II) and Cd(II) ions, respectively. The mean free energies of adsorption were found to be between 8 and 16 kJ/mol for Pb(II) and Cd(II) ions; this suggested that the adsorption of Pb(II) and Cd(II) ions onto CCS occurred with an ion‐exchange process. For two‐target heavy‐metal ion adsorption, a pseudo‐second‐order model and intraparticle diffusion seem significant in the rate‐controlling step, but the pseudo‐second‐order chemical reaction kinetics provide the best correlation for the experimental data. The enthalpy change for the process was found to be exothermic, and the ΔS^θ values were calculated to be negative for the adsorption of Pb(II) and Cd(II) ions onto CCS. Negative free enthalpy change values indicated that the adsorption process was feasible. The studies of the kinetics, isotherm, and thermodynamics indicated that the adsorption of CCS was more effective for Pb(II) ions than for Cd(II) ions. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of cibacron blue F3GA‐attached polyamide hollow fibers for heavy metal removal

Dye‐affinity adsorption has been used increasingly for heavy metal removal. Synthetic hollow fibers have advantages as support matrices in comparison to conventional bead supports because they are not compressible and they eliminate internal diffusion limitations. The goal of this study was to investigate in detail the performance of hollow fibers composed of modified polyamide to which Cibacron Blue F3GA was attached for the removal of heavy metal ions. The Cibacron Blue F3GA loading was 1.2 mmol/g. The internal matrix was characterized by scanning electron microscopy. No significant changes in the hollow fiber cross‐section or outer layer morphology were observed after dye modification. The effect of the initial concentration of heavy metal ions and medium pH on the adsorption efficiency were studied in a batch reactor. The adsorption capacity of the hollow fibers for the selected metal ions [i.e., Cu(II), Zn(II) and Ni(II)] were investigated in aqueous media with different amounts of these ions (10–400 ppm) and at different pH values (3.0–7.0). The maximum adsorptions of metal ions onto the Cibacron Blue F3GA‐attached hollow fibers were 246.2 mg/g for Cu(II), 133.6 mg/g for Zn(II), and 332.7 mg/g for Ni(II). Furthermore, a Langmuir expression was calculated to extend the adsorption equilibrium. Nitric acid (0.1M) was chosen as the desorption solution. High desorption ratios (up to 97%) were observed in all cases. Consecutive adsorption/desorption operations showed the feasibility of repeated use of this novel sorbent system. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 3089–3098, 2002; DOI 10.1002/app.2338     

Preparation of amidoximated polyester fiber and competitive adsorption of some heavy metal ions from aqueous solution onto this fiber

In this study, a fibrous adsorbent containing amidoxime groups was prepared by graft copolymerization of acrylonitrile (AN) onto poly(ethylene terephthalate) (PET) fibers using benzoyl peroxide (Bz₂O₂) as initiator in aqueous solution, and subsequent chemical modification of cyano groups by reaction with hydroxylamine hydrochloride in methanol. The grafted and modified fibers were characterized by FTIR, TGA, SEM, and XRD analysis. The crystallinity increased, but thermal stability decreased with grafting and amidoximation. The removal of Cu(II), Ni(II), Co(II), Pb(II), and Cd(II) ions from aqueous solution onto chelating fibers were studied using batch adsorption method. These properties were investigated under competitive conditions. The effects of the pH, contact time, and initial ion concentration on the removal percentage of ions were studied. The results show that the adsorption rate of metal ions followed the given order Co(II) > Pb(II) > Cd(II) > Ni(II) > Cu(II). The percentage removal of ions increased with initial ion concentration, shaking time, and pH of the medium. Total metal ion removal capacity was 49.75 mg/g fiber on amidoximated fiber. It was observed that amidoximated fibers can be regenerated by acid without losing their activity, and it is more selective for Pb(II) ions in the mixed solution of Pb‐Cu‐Ni–Co‐Cd at pH 4. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Hexafunctional poly(propylene glycol) based hydrogels for the removal of heavy metal ions

Two types of degradable poly(propylene glycol) (PPG) hydrogels that are suitable for the absorption of heavy metals have been presented. The PPG‐O‐P(O)Cl₂ fragments obtained by treating hexafunctional PPG with phosphorous oxychloride (POCl₃) react with 1,3‐propanediamine (PDA; Gel‐1 ) or PDA together with 1,2‐ethanedithiol ( Gel‐2 ), to yield cross‐linked and water‐swellable hydrogels in a one‐pot method. This protocol for the fabrication of PPG hydrogels exhibits promising advantages over prior methods including a short reaction time, mass‐production, easy separation, and high yield. A series of heavy metal ions were employed to test the adsorptive properties of the hydrogels. Gel‐2 shows better adsorption capacity than Gel‐1 for all the metal ions and the metal ions adsorption efficiency of the two types of hydrogels is in the order of Fe(III) > Pb(II) > Cd(II) > Zn(II) > Cu(II) > Ni(II) > Co(II) > Hg(II). The amounts of metal ions adsorbed increases with metal ion concentration and hydrogel dosage, but decreases with temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40610.     

A novel lead ion‐imprinted chelating nanofiber: Preparation,characterization, and performance evaluation

A novel Pb(II) ion‐imprinted chelating nanofibers (nIIP), synthesized by combining electrospinning with surface ion imprinting technique, was reported in this study. nIIP was characterized with Fourier transmission infrared spectrometry and scanning electron microscopy, respectively. The performance of nIIP for Pb(II) sorption was conducted through a batch adsorption experiments. Experimental data showed that adsorption capacity of nIIP was much higher than that of non‐ion imprinted chelating acrylic microfibers (mNIP) derived from commercial available acrylic microfibers, and adsorption behaviors agreed well with pseudo‐second‐order kinetic and Langmuir isotherm model. The values of Gibbs free energy change derived from experimental data suggested that the adsorption Pb(II) on nIIP is spontaneous and favorable at high temperature. In addition, nIIP had the highest selectivity among three tested fibrous adsorbents for Pb(II) from binary metal solution, the selectivity coefficients for Pb(II) from binary metal solution of Pb(II)/Cu(II), Pb(II)/Ni(II), and Pb(II)/Cd(II) onto nIIP were 47, 101, and 162, respectively. Besides, a forty adsorption/desorption cycles revealed that nIIP was a promising recyclable adsorbent. In conclusion, the novel nIIP is a highly effective adsorbent for enrichment and separation of Pb(II) in the presence of competitive ions in aqueous solution, and it is potential to be applied for recovering metals from heavy metal polluted industrial wastewater such as Pb(II)/Cd(II), Pb(II)/Ni(II), and Pb(II)/Cu(II) polluted wastewater. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41507.     

A new functionalized reduced graphene oxide adsorbent for removing heavy metal ions in water via coordination and ion exchange

ABSTRACT

Heavy metal ion pollution has become a serious problem. In this paper, a new type of adsorbent, reduced graphene oxide grafted by 4-sulfophenylazo groups (RGOS), was synthesized to adsorb heavy metal ions in an aqueous solution via two kinds of adsorption modes, ion exchange and coordination. The maximum adsorption capacities of the RGOS for Pb(II), Cu(II), Ni(II), Cd(II) and Cr(III) were 689, 59, 66, 267 and 191 mg/g, respectively. Adsorption equilibrium time of RGOS for heavy metal ions is no more than 10 min. Adsorption mechanism was supposed based on elemental analyses, adsorption data, and Fourier transform infrared spectra.     

Specific heavy metal ion recovery with ion‐imprinted cryogels

In this study, the functional monomers, N‐methacryloyl‐l ‐aspartic acid and N‐methacryloyl‐l ‐cysteine were synthesized through a reaction between appropriate amino acids and methacryloyl chloride. Then, Pb(II) or Cd(II) ion‐imprinted 2‐hydroxyethyl methacrylate based cryogels were prepared by free radical polymerization method under partially frozen conditions. Following the characterization of matrices, adsorption of heavy metal ions was examined in batch mode from aqueous solution considering several parameters affecting the adsorption performance. The actual adsorption capacities were 44.5, 65.3, and 86.7 mg/g for Cd‐1, Cd‐2, and Cd‐3 cryogels meanwhile those were 41.9, 86.3, and 122.7 mg/g for Pb‐1, Pb‐2, and Pb‐3 cryogels, respectively at optimum pH: 5.5. By increasing temperature, adsorption capabilities of both cryogels were inhibited because of the electrostatic nature of coordinated covalent bonds and collapsing of coordination spheres. The adsorption process was very fast, the equilibrium adsorption was achieved in about 60 min, which was directly related to macroporous structure and interconnected flow‐channels of cryogels. Kinetics and adsorption isotherms were also studied. Langmuir isotherms and pseudo‐second order kinetic model were well suited to adsorption data, which also indicated that the process occurred without any diffusion restrictions or steric hindrances. Finally, the competitive adsorption studies were performed using multi‐ion containing synthetic wastewater to show whether the cryogels developed are suitable for specific heavy metal recycling or not. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43095.     

Removal of Cd(II), Hg(II), and Pb(II) ions from aqueous solution using p(HEMA/chitosan) membranes

An interpenetration network (IPN) was synthesized from 2‐hydroxyethyl methacrylate (HEMA) and chitosan, p(HEMA/chitosan) via UV‐initiated photo‐polymerization. The selectivity to different heavy metal ions viz Cd(II), Pb(II), and Hg(II) to the IPN membrane has been investigated from aqueous solution using bare pHEMA membrane as a control system. Removal efficiency of metal ions from aqueous solution using the IPN membranes increased with increasing chitosan content and initial metal ions concentrations, and the equilibrium time was reached within 60 min. Adsorption of all the tested heavy metal ions on the IPN membranes was found to be pH dependent and maximum adsorption was obtained at pH 5.0. The maximum adsorption capacities of the IPN membrane for Cd(II), Pb(II), and Hg(II) were 0.063, 0.179, and 0.197 mmol/g membrane, respectively. The adsorption of the Cd(II), Hg(II), and Pb(II) metal ions on the bare pHEMA membrane was not significant. When the heavy metal ions were in competition, the amounts of adsorbed metal ions were found to be 0.035 mmol/g for Cd(II), 0.074 mmol/g for Hg(II), and 0.153 mmol/g for Pb(II), the IPN membrane is significantly selective for Pb(II) ions. The stability constants of IPN membrane–metal ions complexes were calculated by the method of Ruzic. The results obtained from the kinetics and isotherm studies showed that the experimental data for the removal of heavy metal ions were well described with the second‐order kinetic equations and the Langmuir isotherm model. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Controllable preparation and heavy‐metal‐ion adsorption of lignosulfonate‐polypyrrole composite nanosorbent

Lignosulfonate‐polypyrrole (LS‐PPY) composite nanospheres were prepared facilely via an in situ polymerization of pyrrole monomers in the presence of lignosulfonate as a dispersant and ammonium persulfate as an oxidant. The LS‐PPY composite was characterized with Fourier Transform infrared spectroscopy (FTIR), thermogravimetric analysis, wide‐angle X‐ray diffraction (XRD), scanning electron microscopy (SEM), field‐emission SEM, and transmission electron microscopy. Uniform LS‐PPY solid composite nanospheres with an average diameter of 154 nm were obtained. The LS‐PPY composite nanospheres were applied to adsorption of Ag(I) and Pb(II) ions from aqueous solutions. Maximum adsorption capacities of Ag(I) and Pb(II) were up to 759.3 mg g⁻¹ and 207.5 mg g⁻¹, respectively. Furthermore, the silver ions can be reduced to metallic silver nanowires through a redox reaction between the LS‐PPY composite nanospheres and the silver ions. A productive no‐template route to fabrication of LS‐PPY composite nanospheres with controllable size and heavy‐metal‐ion adsorption ability was achieved. POLYM. COMPOS., 36:1546–1556, 2015. © 2014 Society of Plastics Engineers     

Synthesis,characterization, and adsorption behavior of aminophosphinic grafted on poly(styrene‐Co‐divinylbenzene) for divalent metal ions in aqueous solutions

In the present work, two novel aminophosphinic acid ligands grafted on poly(styrene‐1%divinylbenzene) (St‐1%DVB) have been synthesized by reacting polymer precursors bearing primary amino groups with benzaldehyde (or propionaldehyde) and phenylphosphinic acid by the “one‐pot” Kabatachnik‐Fields reaction. The resins functionalized with aminophosphinic pendant groups were characterized by means of Fourier transform infrared spectroscopy (FTIR), thermal analysis, energy dispersive X‐ray microanalysis (EDX), and Scanning electron microscopy (SEM) imaging. Its adsorption capacity for divalent metal ions such as Cu(II) and Ni(II) were investigated. The adsorption procedure of Cu(II) and Ni(II) ions on polymer‐grafted aminophosphinic acid ligands was carried out by batch experiments. The result also shows that the adsorption process was best described by a pseudo‐second‐order kinetic equation and by the Langmuir adsorption isotherm. The best maximum adsorption capacity was obtained for resin with aminobenzylphosphinic acid groups [1.46 mg Cu(II)/g and 1.36 mg Ni(II)/g]. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers     

Adsorption of lead and copper on modified polyacrylonitrile bead

Porous sorbents were prepared from copolymer of acrylonitrile‐methylmethacrylate‐2‐acrylamidomethylpropensulfonic acid and copolymer of acrylonitrile with vinylimidazol. The sorbent obtained from the former copolymer was modified with hydroxylamine, sodium hydroxide, and hydrazinehydrochloride under optimal conditions to obtain amidooxyme, carboxylic, and hydrazide groups. These functional groups introduced in the modified sorbent and the imidazol group in the sorbent of acrylonitrile and vinylimidazol showed high ability to form complexes with heavy metals. The adsorption properties of the porous chelate‐forming sorbents obtained were studied with Pb(II) and Cu(II) ions. The order of the polymer sorbents toward sorption of Pb(II) and Cu(II) ions was determined. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 283–288, 2001