Metal ion binding properties of novel wool powders

Wool fibres have shown potential for the removal and recovery of toxic chemical and metal ions; however, their slow kinetics of binding has limited their widespread application. In this study three wool powders have been prepared from chopped wool fibre using various milling operations. Brunauer, Emmett, Teller analysis (BET) showed negligible change in surface area and Positron annihilation lifetime spectroscopy indicated no change in nanoporosity of the powders on processing. Binding of the transition metal ions, Co²⁺, Cu²⁺, and Cd²⁺ was investigated over the pH range 3–9 at ambient temperature (23°C) using their respective radioisotopes (i.e. ⁵⁷Co, ⁶⁴Cu, or ¹⁰⁹Cd). The optimum pH for binding of Cu²⁺ and Cd²⁺ was in the range 6–8, while Co²⁺ absorption peak was sharp at pH 8. The rate of uptake of Cu²⁺ for each of the wool powder was dramatically faster (～ 42 fold) than that of the wool fibre. In comparison with commercial cation exchange resins, the wool powders showed significantly higher (two to nine fold) metal ion loading capacity. Selective binding of the metal ions could be enhanced by varying pH and/or incubation times. The use of radioisotopes to monitor the metal ion binding allowed the development of a highly sensitive and rapid high‐throughput analysis method for assessing wool powder binding properties. The ability to produce large quantities of wool powders and their ease of handling indicate that they have potential for application in separation and recovery of metal ions from industrial effluents and environmental waterways. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Formation of thermosensitive copolymer beads having phosphinic acid groups and adsorption ability for metal ions

Hydrophilic thermosensitive copolymer beads having phosphinic acid groups were prepared by suspension copolymerization of acryloyloxypropyl n‐octylphosphinic acid (APPO), N‐isopropyl acrylamide (NIPAAm), and tetraethyleneglycol dimethacrylate (4G). The thermosensitivity and the adsorption ability of the copolymer beads for metal ions beads were studied. The APPO‐NIPAAm‐4G copolymer beads were obtained in a good yield by suspension copolymerization of monomers (APPO, NIPAAm, and 4G) dissolved in chloroform, in a saturated Na₂SO₄ aqueous solution in the presence of surfactant and MgCO₃. The APPO‐NIPAAm‐4G copolymer beads had higher adsorption ability for lanthanide metal ions (Eu³⁺, Sm³⁺, Nd³⁺, or La³⁺) than for main transition metal ions (Cu²⁺, Ni²⁺, or Co²⁺). Furthermore, it was also found that the APPO‐NIPAAm‐4G copolymer beads had selective adsorption ability between lanthanide metal ions, and the order of adsorption ability for lanthanide metal ions was as follows: Eu³⁺ > Sm³⁺ > Nd³⁺ > La³⁺. The selective adsorption for these metal ions from their mixed solutions was performed by both a batch method and a column method. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 449–460, 2006     

Metal Binding to Sodium Heparin Monitored by Quadrupolar NMR

Heparins and heparan sulfate polysaccharides are negatively charged glycosaminoglycans and play important roles in cell-to-matrix and cell-to-cell signaling processes. Metal ion binding to heparins alters the conformation of heparins and influences their function. Various experimental techniques have been used to investigate metal ion-heparin interactions, frequently with inconsistent results. Exploiting the quadrupolar ²³Na nucleus, we herein develop a ²³Na NMR-based competition assay and monitor the binding of divalent Ca²⁺ and Mg²⁺ and trivalent Al³⁺ metal ions to sodium heparin and the consequent release of sodium ions from heparin. The ²³Na spin relaxation rates and translational diffusion coefficients are utilized to quantify the metal ion-induced release of sodium ions from heparin. In the case of the Al³⁺ ion, the complementary approach of ²⁷Al quadrupolar NMR is employed as a direct probe of ion binding to heparin. Our NMR results demonstrate at least two metal ion-binding sites with different affinities on heparin, potentially undergoing dynamic exchange. For the site with lower metal ion binding affinity, the order of Ca²⁺ > Mg²⁺ > Al³⁺ is obtained, in which even the weakly binding Al³⁺ ion is capable of displacing sodium ions from heparin. Overall, the multinuclear quadrupolar NMR approach employed here can monitor and quantify metal ion binding to heparin and capture different modes of metal ion-heparin binding.     

Selection of RNA-Cleaving TNA Enzymes for Cellular Mg2+ Imaging

Catalytic DNA-based fluorescent sensors have enabled cellular imaging of metal ions such as Mg²⁺. However, natural DNA is prone to nuclease-mediated degradation. Here, we report the in vitro selection of threose nucleic acid enzymes (TNAzymes) with RNA endonuclease activities. One such TNAzyme, T17–22, catalyzes a site-specific RNA cleavage reaction with a k_cat of 0.017 min⁻¹ and K_M of 675 nM. A fluorescent sensor based on T17–22 responds to an increasing concentration of Mg²⁺ with a limit of detection at 0.35 mM. This TNAzyme-based sensor also allows cellular imaging of Mg²⁺. This work presents the first proof-of-concept demonstration of using a TNA catalyst in cellular metal ion imaging.     

Adsorption characteristics of metal ions by CO2-fixing Chlorella sp. HA-1

Single and binary metal systems were employed to investigate the removal characteristics of Pb²⁺, Cu²⁺, Cd²⁺, and Zn²⁺ by Chlorella sp. HA-1 that were isolated from a CO₂ fixation process. Adsorption test of single metal systems showed that the maximum metal uptakes were 0.767 mmol Pb²⁺, 0.450 mmol Cd²⁺, 0.334 mmol Cu²⁺ and 0.389 mmol Zn²⁺ per gram of dry cell. In the binary metal systems, the metal ions on Chlorella sp. HA-1 were adsorbed selectively according to their adsorption characteristics. Pb²⁺ ions significantly inhibited the adsorption of Cu²⁺, Zn²⁺, and Cd²⁺ ions, while Cu²⁺ ions decreased remarkably the metal uptake of Cd²⁺ and Zn²⁺ ions. The relative adsorption between Cd²⁺ and Zn²⁺ ions was reduced similarly by the presence of the other metal ions.     

An Exceptionally Selective DNA Cooperatively Binding Two Ca2+ Ions

Ca²⁺ is a highly important metal ion in biology and in the environment, and thus there is extensive work in developing sensors for Ca²⁺ detection. Although many Ca²⁺‐binding proteins are known, few nucleic acids can selectively bind Ca²⁺. DNA‐based biosensors are attractive for their high stability and excellent programmability. We report a RNA‐cleaving DNAzyme, EtNa, cooperatively binding two Ca²⁺ ions but to only one Mg²⁺. Four DNAzymes with known Ca²⁺‐dependent activity were compared, and the EtNa had the best selectivity for Ca²⁺. The EtNa is 90 times more active in Ca²⁺ than in Mg²⁺. Phosphorothioate (PS) modification showed that both non‐bridging oxygen atoms at the scissile phosphate contribute equally to Ca²⁺ binding. The pH–rate profile suggests two concurrent deprotonation reactions. EtNa was further engineered for Ca²⁺ sensing, and found to have a detection limit of 17 μm Ca²⁺ and excellent selectivity. The detection of Ca²⁺ in tap water was performed, and the result was comparable with that by ICP‐MS. This study offers new fundamental insights into Ca²⁺ binding by nucleic acids and improved metal selectivity by having multiple cooperative metal binding sites.     

Preparation of aminoalkyl celluloses and their adsorption and desorption of heavy metal ions

Aminoalkyl celluloses (AmACs) were prepared from 6-chlorodeoxycellulose and aliphatic diamines H₂N(CH₂)_mNH₂ (m = 2, 4, 6, 8). Their adsorption and desorption of divalent heavy metal ions such as Cu²⁺, Mn²⁺, Co²⁺, Ni²⁺ and their mixtures were also investigated in detail. Adsorption of metal ions on AmACs was remarkably affected by the pH of the solution, the metal ion and its initial concentration, and also the number of methylene units in the diamines. No adsorption of metal ions occurred on AmACs in strongly acidic solutions. However, metal ions were adsorbed rapidly on AmACs from weakly acidic solutions and the amount of adsorption increased with increasing pH. The effectiveness of AmACs as adsorbents decreased with increasing length of the methylene moiety, and AmACs from ethylenediamine (m = 2) was most effective. The adsorption of metal ions on AmACs was in the order Cu²⁺ > Ni²⁺ > Co²⁺ > Mn²⁺. Accordingly, their behavior followed the Irving-Williams series and Cu²⁺ ions were preferentially adsorbed from solutions containing metal ion mixtures. The adsorbed ions were easily desorbed from the AmACs by stirring in 0.1 M HCl.     

Application of a Novel Hybrid Cation Exchange Material in Metal Ion Separations

A novel hybrid cation exchange material of the class of tetravalent metal acid (TMA) salt, titanium diethylene triamine pentamethylene phosphonate (TiDETPMP) has been synthesized by the sol gel method. The material has been analyzed by spectroscopy and thermal methods. Physico-chemical and ion exchange characteristics have also been studied. The distribution coefficient (K _d ) has been determined in aqueous as well as various electrolyte media/concentrations for Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺ (transition metal ions) and Cd²⁺, Hg²⁺, Pb²⁺, Bi³⁺ (heavy metal ions) using TiDETPMP. Based on the differential affinity/selectivity, the breakthrough capacity (BTC) and elution behavior of various metal ions towards TiDETPMP, a few binary and ternary metal ions separations have been carried out.     

Preparation of Chelating Resins Containing a Pair of Neighboring Carboxylic Acid Groups and the Adsorption Characteristics for Heavy Metal Ions

Abstract

For the functional enhancement of chelating resins containing carboxylic acids, copolymer beads were prepared by suspension polymerization of styrene (St), methyl methacrylate (MMA), and divinylbenzene (DVB) in the presence of toluene as diluent. The phenyl rings of the beads were directly chloromethylated, and the carboxylic ester groups of the beads were converted into hydroxymethyl groups by reduction followed by chlorination to give chloromethyl groups, respectively. The chelating resins containing a pair of neighboring carboxylic acid groups (NCAGs) were obtained by the alkylation of chloromethyl groups in copolymer beads with diethyl malonate in the presence of sodium hydride followed by hydrolysis using aqueous alkali solution. Accordingly, the structural effects of the resins on the adsorption of heavy metal ions were investigated. Poly(St‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, and Cu²⁺, whereas poly(MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Cu²⁺, Cd²⁺, and Co²⁺. On the other hand, poly(St‐co‐MMA‐co‐DVB)‐based chelating resin containing NCAGs showed adsorption abilities toward heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, Co²⁺, and Cu²⁺: a synergistic effect on the adsorption of heavy metal ions like Pb²⁺, Cd²⁺, Hg²⁺, and Co²⁺ was observed. The adsorption ability of poly(St‐co‐MMA‐co‐DVB)‐based chelating resin among three kinds of chelating resins was relatively good.     

Synthesis and photophysical behavior of a water‐soluble coumarin‐bearing polymer for proton and Ni2+ ion sensing

BACKGROUND: In recent years, many fluorescent chemosensors with various macromolecular structures have been prepared for the detection of protons or metal cations in the environment. Most of this research is focused on polymer sensors with fluorescent recognition sites in the main chain. In this case, the fluorescent recognition sites are covalently bonded to the polymer chain, and thus the polymer shows photophysical properties as a chemosensor for protons and metal ions. RESULTS: An acrylic monomer bearing coumarin moieties, 7‐hydroxy‐4‐methyl‐8‐(4′‐acryloylpiperazin‐1′‐yl)methylcoumarin, was synthesized. This was then copolymerized with N‐vinylpyrrolidone to obtain a blue fluorescent material. The fluorescent copolymer has good solubility in aqueous solution. Its main photophysical properties were determined in relation to its use as a sensor for protons and metal cations. It is an efficient ‘off‐on’ switcher for pH between 3.02 and 12.08. Additionally, the polymer sensor is selective to Ni²⁺ ions, with the increase in the fluorescence intensity depending on Ni²⁺ ion concentrations in the range 0.33 × 10^?5–7.67 × 10^?5 mol L^?1. CONCLUSION: The results suggest that this copolymer may offer potential as a reusable polymer sensor for protons and Ni²⁺ ions in aqueous solution. Copyright © 2009 Society of Chemical Industry     

Biosorption of Heavy Metals by Anoxybacillus gonensis Immobilized on Diaion HP-2MG

Abstract

The determination of trace metal ions usually requires previous separation and preconcentration stages in order to cope with low levels and to remove the interfering components. Nowadays emphasis is given to the utilization of microorganisms because of their great ability to absorb metal ions from aqueous solution. In this paper, for this, Zn²⁺, Fe³⁺, Cu²⁺, Cd²⁺, Ni²⁺, Co²⁺, and Pb²⁺ ions at trace levels have been separated and preconcentrated on a column containing a bacterium, Anoxybacillus gonensis immobilized on Diaion HP-2MG as a new biosorption system prior to their atomic absorption spectrometric determinations. The effects of some analytical parameters were investigated. Optimum pH values were found to be 6 for Zn, Fe, Cu and Pb, 8 for Cd, Ni, and Co. Recoveries of Zn²⁺, Fe³⁺, Cu²⁺, Cd²⁺, Ni²⁺, Co²⁺, and Pb²⁺ were 95 ± 3, 98 ± 6, 96 ± 2, 98 ± 2, 97 ± 2, 95 ± 4 and 95 ± 3 at 95% confidence level, respectively. No significant matrix interferences on the quantitative recoveries of the analyte ions were observed. Preconcentration factors of the anlayte ions were calculated as 50 for Zn, Cd and Pb, and 75 for Fe, Cu, Ni, and Co. The limits of detection for the analyte ions were in the range 0.2–1.3 µg L^?1. The procedure was validated by spike addition and analysis of standard reference materials.     

基于冠醚的离子识别响应型智能材料研究新进展

金属离子对生物体的生命活动起着核心的作用,而一些重金属离子(如Pb²⁺、Hg²⁺)在很低浓度时就对生物具有极强的毒性;因此,研究具有金属离子识别特性的智能材料具有重要的理论价值和实用意义。冠醚具有选择性地络合金属离子的能力,研究者们将冠醚的离子识别特性与聚(N-异丙基丙烯酰胺)的相变行为特性相结合制备了一系列离子识别响应型智能材料。综述了近年来基于18-冠-6和15-冠-5两种冠醚分子的离子识别响应型智能材料的研究新进展。目前,基于冠醚的离子识别响应型智能材料仍多处于基础研究阶段,还需要进一步系统深入研究和开发完善。     

Effect of Ni<Superscript>2+</Superscript>, V<Superscript>4+</Superscript> and Mo<Superscript>6+</Superscript> concentration on iron oxidation by <Emphasis Type="Italic">Acidithiobacillus ferrooxidans</Emphasis>

The ferrous oxidation ability of Acidithiobacillus ferrooxidans was studied in the presence of Ni²⁺, V⁴⁺ and Mo⁶⁺ in 9 K media in order to implement the culture in the bioleaching of spent catalyst. The rate of iron oxidation decreased with increasing concentration of metal ions, but the rate of inhibition was metal-ion dependent. The tolerance limit was critical at a concentration of 25 g/L Ni²⁺, 5 g/L V⁴⁺ and 0.03 g/L Mo⁶⁺. The growth rate of microorganisms was negligible at concentrations of 6 g/L V⁴⁺ and 0.04 g/L Mo⁶⁺. Levels and degree of toxicity of these ions have been quantified in terms of a toxicity index (TI). The toxicity order of metal ions was found to be Mo⁶⁺>V⁴⁺>Ni²⁺. The significance and relevance of multi-metal ion tolerance in Acidithiobacillus ferrooxidans has been highlighted with respect to bioleaching of spent refinery catalyst.     

Synthesis of Starch-Stabilized Ag Nanoparticles and Hg2+ Recognition in Aqueous Media

The starch-stabilized Ag nanoparticles were successfully synthesized via a reduction approach and characterized with SPR UV/Vis spectroscopy, TEM, and HRTEM. By utilizing the redox reaction between Ag nanoparticles and Hg²⁺, and the resulted decrease in UV/Vis signal, we develop a colorimetric method for detection of Hg²⁺ ion. A linear relationship stands between the absorbance intensity of the Ag nanoparticles and the concentration of Hg²⁺ ion over the range from 10 ppb to 1 ppm at the absorption of 390 nm. The detection limit for Hg²⁺ ions in homogeneous aqueous solutions is estimated to be ~5 ppb. This system shows excellent selectivity for Hg²⁺ over other metal ions including Na⁺, K⁺, Ba²⁺, Mg²⁺, Ca²⁺, Fe³⁺, and Cd²⁺. The results shown herein have potential implications in the development of new colorimetric sensors for easy and selective detection and monitoring of mercuric ions in aqueous solutions.     

SPOTLIGHT ON MANUFACTURING TRENDS IN JAPAN

Three reactive and functional polymers were synthesized by reacting formaldehyde with the phenolic Schiff bases derived from 4,4′-diaminodiphenylsulfone and o-, m-, and p-hydroxybenzaldehydes, respectively. The metal ion uptake behavior of these resins towards Cu²⁺, Ni²⁺, Co²⁺, and UO₂ ²⁺ ions in dilute aqueous media was studied. The optimum conditions for the absorption of metal ions were determined by varying the various parameters like contact time, size of the sorbents, concentration of the metal ion solutions, and the pH of the reaction medium. Suitable conditions were ascertained for preferential adsorption of the above metal ions from the salt solutions containing other interfering ions such as Na⁺, K⁺, and Mg²⁺. Presence of these alkali and alkaline earth metal ions in the salt solutions did not affect the adsorption behavior of the resins. It was observed that the structural features of the resins have a profound effect on the uptake characteristics. The position of the OH group present in the meta position with respect to the imine nitrogen atom in the resin, demonstrated a significant influence on the extent of metal ion adsorption by the resin. Out of the three resins reported here, the resin derived from the Schiff base of m-hydroxybenzaldehyde-4,4′-diaminodiphenylsulfone showed higher efficiency in uptake of metal ions from the solutions than the corresponding resins derived from the Schiff bases of o- and p-hydroxybenzaldehyde-4,4′-diaminodiphenylsulfone.     

Preparation of poly (MAA)‐crosslinked pregelled starch graft copolymer and its application in waste water treatments

Propelled starch (PG) was first crosslinked with epichlorohydrin to obtain insoluble crosslinked pregelled starch (CPS). The latter was graft copolymerized with different amounts of Methacrylic acid using potassium persulphate as initiator. This was done to obtain six levels of poly (MAA)‐crosslinked pregelled starch graft copolymers (PMCPS) having different graft yields (expressed as meq COOH/100 g starch) with increasing order and designated as (PMCPS 1 to PMCPS 6). The latter copolymers were dispersed in aqueous solution of heavy metal ions (Cu²⁺, Pb²⁺, Cd²⁺, and Hg²⁺) and filtered to form polymer‐metal ions complex. Different factors affecting the heavy metal ions removal such as pH, extent of grafting, treatment time and starch dose were studied in detail. It was found from the obtained results that; the residual metal ions removal from their aqueous solutions increased with (a) increasing the extent of grafting of PMCPS i.e., from PMCPS 1 to PMCPS 6; (b) Increasing the pH of the metal ions solution complex from 1 to 8; (c) increasing the starch dosage from 0.25 to 2.0% (W/V), then leveled off thereafter, (d) increasing the time of the reaction up to 20 min then leveled off after that. On the other hand, Pb, Cd and Hg ions were also removed from their solutions with different extent. Furthermore, the prepared copolymer could be recovered by washing the metal ions from the complex with weak acid 1N HNO₃ (pH 2) and the metal‐binding activity of the starch was slightly reduced by this process. Finally, the ability of PMCPS to remove three types of basic dyes from their solutions was also reported. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid): Synthesis,characterization, and retention properties for environmentally impacting metal ions

Poly(2‐acrylamido glycolic acid‐co‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid) [P(AGA‐co‐APSA)] was synthesized by radical polymerization in an aqueous solution. The water‐soluble polymer, containing secondary amide, hydroxyl, carboxylic, and sulfonic acid groups, was investigated, in view of their metal‐ion‐binding properties, as a polychelatogen with the liquid‐phase polymer‐based retention technique under different experimental conditions. The investigated metal ions were Ag⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Pb²⁺, and Cr³⁺, and these were studied at pHs 3, 5, and 7. P(AGA‐co‐APSA) showed efficient retention of all metal ions at the pHs studied, with a minimum of 60% for Co(II) at pH 3 and a maximum close to 100% at pH 7 for all metal ions. The maximum retention capacity (n metal ion/n polymer) ranged from 0.22 for Cd²⁺ to 0.34 for Ag⁺. The antibacterial activity of Ag⁺, Cu²⁺, Zn²⁺, and Cd²⁺ polymer–metal complexes was studied, and P(AGA‐co‐APSA)–Cd²⁺ presented selective antibacterial activity for Staphylococcus aureus with a minimum inhibitory concentration of 2 μg/mL. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Polymer hydrogel cross-linked by inorganic nanoparticles for removing trace metal ions

Hydrogels for absorbing metal ions in wastewater have attracted more attentions in the environmental field especially for recent years. The removal efficiency of hydrogel adsorbents for eliminating metal ions is highly related with the effective contact between adsorbents and adsorbates. However, poor water absorption capacity of the hydrogel adsorbents would restrict on the expose of adsorption sites to the targeted subjects, causing undesirable removal ratio (RR) especially for metal ions at trace level. Thereby, the reported hydrogel adsorbents mainly focus on the removal of high content but not the trace level of metal ions so far. In this work, poly(acrylamide) (PAM)/poly(acrylic acid) (PAA)/Ca(OH)₂ composite hydrogel is applied to adsorb trace metal ions. Swelling ratio of such PAM/PAA/Ca(OH)₂ gel reaches 2,530 g/g, resulting in effective exposure of active sites and further expected RR for trace metal ions. The RRs of such adsorbent for Cu²⁺ (initial concentration C₀ = 0.064 mg/L), Al³⁺ (C₀ = 0.27 mg/L), Co²⁺ (C₀ = 0.59 mg/L), Cr⁶⁺ (C₀ = 0.52 mg/L), Mn²⁺ (C₀ = 0.55 mg/L), Ni²⁺ (C₀ = 0.59 mg/L), Zn²⁺ (C₀ = 0.65 mg/L), Ag⁺ (C₀ = 1.08 mg/L), and La³⁺ (C₀ = 1.39 mg/L) are 56.6, 80.8, 41.3, 29.3, 34.6, 44.6, 55.9, 45.8, and 35.5%, respectively. This work broadens the application of hydrogel adsorbent for eliminating trace metal ions from polluted water.     

The preparation and properties of chelates of transition metal ions with the homopolymer and copolymers of p-vinylbenzoylacetone

p-Vinylbenzoylacetone (VBA) was prepared by the condensation of p-vinylacetophenone and ethyl acetate. This monomer was homopolymerized and copolymerized with acrylamide or maleic anhydride to produce polymers which would chelate substantial amounts of transition metal ions such as Cu²⁺, Ni²⁺, Co²⁺, Eu³⁺, and VO²⁺. In the case of the Cu²⁺ and Ni²⁺ chelates, about 80–90% of the metal ion could be eluted by dilute mineral acids. The resulting eluted products apparently have a somewhat porous structure because they are capable of rechelating these ions from water solution, even though the solid homopolymer which had not been chelated and eluted is too hydrophobic to chelate very much metal ion from water solution. The eluted Cu²⁺ chelate readily reaccepted Cu²⁺ ions from water solution and discriminated against Ni²⁺ almost completely. However, the eluted Ni²⁺ chelate would reaccept both Cu²⁺ and Ni²⁺ ions, but exhibited a strong preference for Cu²⁺ ions in competitive batch experiments. The VO²⁺ chelate was an effective heterogeneous phase catalyst for the epoxidation of allyl alcohols such as geraniol with tert-butylhyroperoxide. The chelate was stable under these oxidative conditions and could be recovered unchanged and reused.     

Studies of Retention and Reusable Capacities of Melamine Formaldehyde Based Terpolymer Against Some Toxic Metal Ions by Batch Equilibrium Method

Chelating terpolymer resin was synthesized and characterized by elemental, physico-chemical, spectral, SEM, XRD, and GPC to elucidate the structure and properties of the terpolymer. Ion-exchange analysis involving evaluation of metal ion uptake in different electrolyte concentrations, pH, and time have been studied to assess the retention capacities of the terpolymer for the metal ions viz. Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, and Pb²⁺. The adsorption isotherm was evaluated using the Langmuir and Freundlich isotherms models and the results were found best fitting with each other. The resin can be successfully used in the field of recovery of metal ions from effluents and contaminated water.