Chelating Ion Exchange Research Articles

Adsorptive Removal of Thorium(IV) from Aqueous Solutions Using Synthesized Polyamidoxime Chelating Resin: Equilibrium, Kinetic, and Thermodynamic Studies

In this study, an amidoximated chelating ion exchange resin was prepared by poly-acrylonitrile (PAN) grafted potato starch. The adsorbent characterizations such as specific surface area, pore volume, average pore radius, and Fourier transform infrared (FTIR) spectrum of the resin were measured. The effects of pH, adsorbent dosage, contact time, initial concentration of thorium ion, and temperature on adsorption of thorium ion from aqueous solutions were investigated. Four isotherm models including Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin were applied to analyze the equilibrium isotherm data. The results showed that Langmuir and Temkin models had a good agreement with experimental data. The maximum capacity of the adsorbent using the Langmuir isotherm model was 227.27 mg · g−1. The kinetic models like pseudo-first-order, pseudo-second-order, Elovich, and intraparticle were examined to describe the adsorption process. The kinetics of the adsorption process was found to follow the pseudo-second-order kinetic model. The thermodynamic parameters (ΔG°, ΔH°, ΔS°) were also calculated using equilibrium constant values at various temperatures (25, 35, 45, 55°C) and the positive value for ΔH° showed an endothermic adsorption process. The study suggests that the prepared adsorbent has promising potential for the removal of thorium from wastewaters.

Thermodynamics of Cr(VI) Adsorption on Thiourea Chelating Ion Exchange Fiber

A chelating ion exchange fiber containing thioureido groups for the removal of Cr (VI) has been prepared from chloramethylated styrene grafted polypropylene fiber (2.96 mmol/g Cl) reacted with thiourea, batch adsorption experiments are adopted to investigate its adsorption equilibrium properties, Adsorption isotherms at various temperatures were obtained. Langmuir linear equation model can well describe the adsorption equilibrium data suggesting that the adsorption process involves both chemisorption and physisorption. The values of thermodynamic parameters, including ΔH, ΔG and ΔS, indicate that the adsorption of Cr (VI) is a spontaneous, entropy-driven and endothermic process.

Studies, Synthesis and Characterization of Chelation Ion-Exchange Properties of Copolymer Resin Derived from 8-Hydroxyquinoline-Formaldehyde-Pyrogallol

Chelating ion-exchange resin was synthesized by the condensation of 8-hydroxyquinoline with pyrogallol using formaldehyde as a cross-linking agent at 120oC in DMF in the presence of hydrocloric acid catalyst. The resin was characterized by elemental analysis and FTIR. The morphology of the synthesis resin was examined by optical photograph and scanning electron microscopy (SEM).The physicochemical properties of the resin were studied. The cation exchange capacity was measured and the effect of pH and metal ion concentration on the ability of the ion exchange were studied. The ratio of cation exchange reaction and the distribution coefficient in tartaric acid medium at different pH were also studied using the method of batch equilibration.

Synthesis, Characterization and Chelation Ion-Exchange Studies of a Resin Copolymer Derived From 8-Hydroxyquinoline-Formaldehyde-Pyrogallol

An ion exchange resin chelator was synthesized from 8-hydroxyquinoline and pyrogallol using formaldehyde as a crosslinking agent to 120°C in a solution of DMF. The resin was characterized by elemental analysis and FTIR. The morphology of the synthesis resin was examined by optical photograph and scanning electron microscopy (SEM). The physicochemical properties of the resin were studied. The cation exchange capacity was measured and the effect of pH and metal ion concentration on the ability of the ion exchange were studied. The ratio of cation exchange reaction and the distribution coefficient in tartaric acid medium at different pH were also studied using the method of batch equilibration.

Ion-exchange Studies of Copolymer Derived from 4,4′-Biphenol

A novel copolymer resin (4,4′-BP-4,4′-ODA-F-II) has been synthesized by condensation polymerization reaction of 4,4′-biphenol and 4,4′-oxydianiline using the linkage of formaldehyde in presence of acid catalyst. The resin composition was determined on the basis of elemental analysis. Solution viscosity measurements in dimethylformamide were carried out to ascertain the characteristic functions and constants. The number average molecular weight was determined by conductometric titration in non-aqueous medium. The copolymer resin was further characterized by UV-Visible, Infra-red and Nuclear magnetic resonance spectroscopy to confine the most probable structure of synthesized copolymer. Thermal analysis was carried out for studying the thermal degradation behavior and kinetic parameters. Thermal degradation curve depicts four decomposition steps after a loss of water molecule and has been discussed with minute details by applying Freeman-Carroll, Sharp-Wentworth and Coat-Redfern equations to evaluate the kinetic parameters i.e., activation energy (Ea), order of reaction (n) and frequency factor (z). The data from Freeman-Carroll method has been used to determine various thermodynamic parameters i.e., entropy change (ΔS), free energy change (ΔF) and apparent entropy (S*). This copolymer is proved to be a selective chelating ion exchanger for certain metal ions such as Fe3+, Cu2+, Hg+2, Ni2+, Co2+, Zn2+, Cd2+ and Pb2+. A batch equilibrium method was employed in the study of selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the copolymer sample and a solution containing the metal ion. The study was carried out over a wide pH range, shaking time and in media of various ionic strengths.

Amidoximation of Cyano Group for Chelating Ion Exchange of Some Heavy Metal Ions from Wastewater

Ion exchange behavior of some heavy metal ions, Pb2+, Ni2+, and Cd2+, onto amidoximated polyacrylonitrile based Ce(IV) phosphate was investigated. Polyacrylonitrile based Ce(IV) phosphate was prepared and followed by functionalization of the cyano group to amidoxime group with hydroxylamine. The amidoximated resin was characterized using FT-IR and SEM. Removal of Pb2+, Ni2+, and Cd2+ ions from aqueous solution was examined by studying some factors using the batch technique such as effect of pH, contact time, initial metal ion concentration, and temperature. Some kinetic and isotherm models had been applied. The calculated amount of the sorbed values in case of the pseudo-second-order model are closer to the experimental data than that of the pseudo-first-order model, and with a correlation coefficients R2 > 0.99. Therefore, the sorption of the three metal ions can be approximated more favorably by the pseudo-second-order model. The sorption process obeys the Freundlich isotherm model. The sorption has an endothermic nature which is indicated by the positive value of the enthalpy change, ΔH, the high positive values of the entropy change, and ΔS show the increased randomness at the solid/solution interface. The obtained negative values of free energy change, ΔG, indicate the feasibility and the spontaneous nature of the sorption process.

The development of novel nickel selective amine extractants: 2,2′-Pyridylimidazole functionalised chelating resin

A chelating ion exchanger, prepared by functionalising Merrifield resin with 2,2′-pyridylimidazole, was utilized to selectively adsorb and separate nickel from other base metal ions in synthetic sulfate solutions. The sorbent material was characterized by scanning electron microscopy (SEM), microanalysis, infrared (IR), X-ray photoelectron spectroscopy (XPS) and BET surface area. The distribution ratio (D) and the sorption capacity of the microspheres toward Ni(II), Cu(II), Co(II) and Fe(II) ions was studied by using the batch and column methods, respectively. Ni(II) followed by Cu(II) showed the highest distribution ratio (D) and the highest sorption efficiency of nickel(II) ions around pH 2. The binary separation of nickel(II) from copper(II), cobalt(II) and iron(II) respectively, undertaken in a column study, through loading the metal ions at pH≈2 followed by selective decomplexation, demonstrated the selectivity of the sorbent material for nickel(II). Thus, 2,2′-pyridylimidazole can be regarded as a nickel-specific extractant.

Flow-Injection Spectrophotometric Determination of Bromate in Bottled Drinking Water Samples Using Chlorpromazine Reagent and a Liquid Waveguide Capillary Cell

In this work, aiming to develop a simple, inexpensive method for the determination of low bromate levels in water samples, a liquid waveguide capillary cell (LWCC) was coupled to a FIA system. The long optical path (100 cm) of the LWCC was used to improve the sensitivity and the limit of detection without resorting to any off-line or in-line preconcentration processes. The spectrophotometric determination was based on the oxidation of chlorpromazine by bromate in an acidic medium, resulting in the formation of a colored radical product. Sulfamic acid was added to the reagent for minimizing the interference of nitrite, and a chelating ion exchange resin was used to remove major cationic interferences. The developed system allowed the determination of bromate within the range between 1 - 20 μg L(-1) with a detection limit of 0.2 μg L(-1).

An innovative integrated system for boron removal from geothermal water using RO process and ion exchange-ultrafiltration hybrid method

In this study, removal of boron from the geothermal water was investigated by an integrated process coupling reverse osmosis (RO) with ion exchange-ultrafiltration hybrid method. Desalination tests were performed by using a mini-pilot scale brackish water reverse osmosis (BWRO) system which was installed at Yenikale Geothermal Heating Center, Izmir. Boron selective chelating ion exchange resin Dowex (XUS 43594.00) with a particle size of 20μm was employed for removal of boron from BWRO permeate of geothermal water. A submerged hollow fiber type ultrafiltration membrane module (ZW-1) was used for filtration. Effect of such process variables as resin concentration in the suspension, flow rates of fresh and saturated ion exchange resins, and flow rate of permeate on the efficiency of the hybrid process for boron removal from RO permeate of geothermal water was studied.

Synthesis of new chelating ion exchange resins derived from guaran and divinylbenzene styrene copolymer for selective adsorption of metal ions

New chelating ion exchange resin containing hydroximate of 5 amino salicylic acid was synthesized by incorporating it in divinylbenzene styrene (DVBS) copolymer. Hydrophilic polysaccharidematrix ofguaran was also used to incorporate hydroximate of 5 amino salicylic acid in it. The resin characteristics were studied by determining its bulk density, specific bulk volume, moisture content, degree of substitution and ion exchange capacity. The resin was characterized by means of IR spectra, Nitrogen content and pH titration. The distribution coefficient values of different metal ions namely Fe(II), Cu(II) , Zn(II) , Cd(II) , Co(II) , Ni(II), Ca(II), U(VI), Cr(VI) & W(VI) was carried out on these resins as a function of pH . Metal analysis was done by Atomic Absorption Spectrophotometer. The hydroximate derivative of guaran is found to be more selective than that of diving benzene co-polymer.

Direct determination of transition metals in mussel tissue digests using high-performance chelation ion chromatography with monolithic silica based chelating ion exchangers

A new high performance chelation ion chromatography method was developed for the direct separation and detection of selected transition metals in shellfish (mussel) tissue digest samples. Using two different bonded silica monolithic chelating stationary phases, exhibiting differing selectivities for metals of interest, were applied within the method. The bonded chelating chemistries were N-hydroxyethyliminodiacetic (HEIDA) and N-(2-hydroxyethyl)-N-(2-[phosphonomethyl)amino]acetic (HEPMA) acids. Quantitative determination of Mn(II), Cd(II) and Zn(II) concentrations within shellfish tissue (Mytilus edulis), following microwave assisted acid digestion. Post-column detection was achieved using spectophotometric detection at 510 nm after reaction with 4-(2-pyridylazo) resorcinol. The eluents employed were 0.5 M KNO3, pH 2.4, for the HEIDA-bonded stationary phase, and 0.1 M KNO3, pH 2.6, for the HEPMA-bonded monolithic column. The HEPMA phase provided improved resolution between Mn(II) and interfering alkaline earth metal cations compared to the HEIDA-bonded phase. Concentrations of metals were determined using standard addition, and Cd(II), Mn(II), and Zn(II) cations were detected at <10 μg g−1, <50 μg g−1 and <700 μg g−1, respectively. Sample analysis using sector field inductively coupled plasma-mass spectrometry (ICP-MS) was carried out to generate comparative data to that obtained using the chromatographic method.

Chelation ion chromatography of alkaline earth and transition metals a using monolithic silica column with bonded N-hydroxyethyliminodiacetic acid functional groups

A commercially available porous silica monolithic column (Onyx Monolithic Si, 100mm×4.6mm I.D.) was ‘in-column’ covalently functionalised with 2-hydroxyethyliminodiacetic acid (HEIDA) groups, and applied to the simultaneous and rapid separation of alkaline earth and transition metal ions, using high-performance chelation ion chromatography (HPCIC). With a 0.3mM dipicolinic acid (DPA) containing eluent, the baseline separation of various common transition and heavy metal ions and the four alkaline earth metal ions could be achieved in under 14min with a flow rate of just 0.8mL/min. Detection was achieved using spectrophotometric detection at 540nm after post-column reaction (PCR) with 4-(2-pyridylazo)-resorcinol (PAR). Significant effects from variation of eluent nature, concentration and temperature upon selectivity and retention were demonstrated with the new monolithic silica chelating phase. Under optimised conditions (0.165M LiNO3 eluent, pH 2.5), peak efficiencies of 54,000, 60,000 and 64,000N/m, for Zn2+, Mn2+ and Cd2+, respectively, were recorded, far exceeding that previously reported for IDA based chelation ion exchange columns.

Modeling of fixed bed column studies for removal of boron from geothermal water by selective chelating ion exchange resins

The efficiency of boron removal from geothermal water was investigated using boron selective ion exchange resins Diaion CRB 02 and Dowex (XUS 43594.00) in a fixed-bed column. The effect of pH and feed flow rate on boron removal from geothermal water was additionally tested using Dowex (XUS 43594.00) resin. Yoon–Nelson and Thomas models were applied to the experimental data to predict the breakthrough curves and model parameters such as rate constants and breakthrough times. The results showed that the models describe the breakthrough curves quite well compared with the all experimental data. Similarly, the model predictions for qo obtained both by Yoon–Nelson and Thomas models greatly fit with the experimental results for all conditions and for both boron selective ion exchange resins.

Nitrilotris(methylenephosphonic) acid as a complexing agent in sorption of heavy metal ions on ion exchangers

In this work the strongly basic anion exchanger Amberlite IRA 402, the weakly basic anion exchangers Purolite A 100 and Purolite A 103 as well as the chelating ion exchangers Purolite S 920 and Purolite S 930 were used to investigate the influence of phase contact time, pH and metal(II) concentration on the sorption of the heavy metal complexes of Cd(II), Pb(II), Cu(II) and Zn(II) with nitrilotris(methylenephosphonic acid), NTMP. These types of complexes are often found in industry where NTMP is used. The studies were carried out in the M(II):NTMP=1:2 system. The sorption capacity of the studied ion exchangers increases with the increase of the initial M(II) ions concentration and the sorbate/ion exchanger ratio. It was found that sorption capacity increases with the increasing temperature and initial pH of metal solution. Equilibrium sorption tests show that chelating ion exchangers as well as the strongly basic anion exchanger have a larger capacity and affinity for sorption of Cd(II), Pb(II), Cu(II) and Zn(II) complexes with NTMP than weakly basic anion exchangers. It was found that the Langmuir and Hill models were more representative to describe complexes sorption than the Freundlich, and Dubinin–Radushkevich ones whereas the kinetic process followed the pseudo second-order pattern.

Selective separation of Cr(III) and Fe(III) from liquid effluents using a chelating resin

This study aimed to assess the selective separation of Cr(III) from Fe(III) from liquid solutions by using a chelating ion exchange resin, Diaion CR 11, from Mitsubishi Chemical Corporation, in the H(+) form. Equilibrium experiments with synthetic solutions of iron and chromium were carried out in batch mode. For both metals favorable adsorption isotherms were obtained, and the experimental data were well described by the Langmuir model. However, the resin exhibited higher affinity for iron than for chromium. The regeneration experiments revealed that, for both metals, HCl provided higher removal efficiencies than H(2)SO(4) and HNO(3). Moreover, precipitation with NaOH allows selectively separate chromium and iron to be stripped from the resin. Experiments in fixed bed operation were carried out to assess the dynamic behavior of the sorption of Cr(III) and Fe(III) into the tested resin by using synthetic and industrial solutions. The experiments with industrial effluent showed that the resin can remove low levels of contaminant transition metal ions, and thus the effluent can be purified for reuse of chromium during periods of 20-25 min. The resin regeneration was achieved with a sequential treatment with HCl and NaOH/H(2)O(2). High efficiencies were observed for both monocomponent and multicomponent systems. A global strategy for separating and recovering Cr(III) from an effluent that also contains Fe(III) is presented, involving the integration of ion exchange (saturation and regeneration phases) and precipitation processes. In conclusion, our approach demonstrates that efficient separation of chromium and iron is possible if ion exchange operation in a fixed bed configuration is optimized and combined with conventional processes such as precipitation.

Chemical Properties of Aluminum Tridecamer Transferred onto Chelating Resin

A transcription and concentration method of Al tridecamer (Al13) to Chelex 100 chelating ion exchange resin was developed to enhance the in situ detection sensitivity of the Al13 in an aqueous solution by 27Al magic angle spinning nuclear magnetic resonance. Based on this method, a new lower limit of Al concentration (at least 10−4 mol/L) required to form Al13 was discovered, which is the lowest detectable level known to date. It was found that once Al13 is transferred onto Chelex 100, which serves as a model compound of a soil surface covered with organic substances and microbes, its stability against pH is considerably enhanced (stable at pH 4–12).

Iminodiacetic acid functionalised organopolymer monoliths: application to the separation of metal cations by capillary high-performance chelation ion chromatography

Lauryl methacrylate-co-ethylene dimethacrylate monoliths were polymerised within fused silica capillaries and subsequently photo-grafted with varying amounts of glycidyl methacrylate (GMA). The grafted monoliths were then further modified with iminodiacetic acid (IDA), resulting in a range of chelating ion-exchange monoliths of increasing capacity. The IDA functional groups were attached via ring opening of the epoxy group on the poly(GMA) structure. Increasing the amount of attached poly(GMA), via photo-grafting with increasing concentrations of GMA, from 15 to 35%, resulted in a proportional and controlled increase in the complexation capacity of the chelating monoliths. Scanning capacitively coupled contactless conductivity detection (sC(4)D) was used to characterise and verify homogenous distribution of the chelating ligand along the length of the capillaries non-invasively. Chelation ion chromatographic separations of selected transition and heavy metals were carried out, with retention factor data proportional to the concentration of grafted poly(GMA). Average peak efficiencies of close to 5,000 N/m were achieved, with the isocratic separation of Na, Mg(II), Mn(II), Co(II), Cd(II) and Zn(II) possible on a 250-mm-long monolith. Multiple monolithic columns produced to the same recipes gave RSD data for retention factors of <15% (averaged for several metal ions). The monolithic chelating ion-exchanger was applied to the separation of alkaline earth and transition metal ions spiked in natural and potable waters.

Application of chelating ion-exchangers Amberlite IRC-718 and Duolite ES-346 in removal of Pt(IV) ions from chloride and chloride-nitrate media

Abstract The chelating ion exchangers of the functional iminodiacetate (Amberlite IRC-718) and amidoxime (Duolite ES-346) groups have been applied for Pt(IV) removal from the chloride (0.1 ÷ 8.0 M HCl) and chloride-nitrate (0.1 M HCl + 0.9 M HNO3, 0.5 M HCl + 0.5 M HNO3, 0.9 M HCl + 0.1 M HNO3) solutions. The monolayer sorption capacities (Q 0) for Amberlite IRC-718 determined from the Langmuir isotherm model were changed from 1.032 to 0.917 mmol g−1 and from 0.948 to 0.831 mmol g−1 in the chloride and chloride-nitrate solutions, respectively. For Duolite ES-346 Q 0 values were equal to 1.120–0.937 mmol g−1 in the chloride solutions and 0.692–0.806 mmol g−1 in the chloride-nitrate systems. The influence of acid concentrations, phase contact time and macrocomponent addition (AlCl3, CuCl2, NiCl2) on Pt(IV) sorption was also studied. The pseudo second order equation provided the best fitting of experimental values. The working and total ion exchange capacities as well as distribution coefficients of Pt(IV) w...

Sorption investigation on the removal of metal ions from aqueous solutions using chelating terpolymer resin

A novel chelating terpolymer resin has been synthesized from anthranilic acid, phenylhydrazine, and formaldehyde by condensation in glacial acetic acid. The structure of the chelating resin was clearly elucidated by use of a variety of spectral techniques, for example FTIR, and 1H and 13C NMR spectroscopy. The average molecular weight of the terpolymer resin was determined by gel-permeation chromatography. The empirical formula and empirical weight of the resin were determined by elemental analysis. The physicochemical properties of the terpolymer resin were determined. Scanning electron microscopy was used to establish the surface features of the chelating resin. The ion-exchange behaviour of the resin for specific metal ions, viz. Fe3+, Co2+, Ni2+, Cu2+, Zn2+, and Pb2+, was evaluated by a batch equilibrium method. The study was extended to three variations: evaluation of metal ion uptake in the presence of different electrolytes at different concentrations; evaluation of metal ion uptake at different pH; and evaluation of metal ion uptake at different times. Further, the reusability of the resin was also determined to assess the efficiency of the resin after a few cycles of sorption. From the results it was observed that the resin acts as an effective chelating ion-exchanger.

Sorption of Zn(II) and Pb(II) ions in the presence of the biodegradable complexing agent of a new generation

The macroporous chelating ion exchangers containing different functional groups i.e. Purolite S-920, Purolite S-930 and Lewatit TP-208 have been used in the sorption process of Zn(II) and Pb(II) ions. The effect of the presence of biodegradable, environmentally friendly aminopolycarboxylate chelating agent, trisodium salt of methylglycinediacetic acid (MGDA) on its sorption capacity was also examined. The investigations were carried out by the static method. Besides the effect of initial concentration of Zn(II) and Pb(II) and the complexing agent the research concerns the influence of solution pH, phase contact time on effectiveness of sorption. The equilibrium and kinetics of Zn(II)–MGDA and Pb(II)–MGDA complexes sorption were obtained and fitted using the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R) models as well as the pseudo first and pseudo second order kinetic models. The intraparticle diffusion model was also used. The results showed that the sorption processes of Zn(II) and Pb(II) complexes with MGDA on Purolite S-920, Purolite S-930 and Lewatit TP-208 followed well the pseudo second order kinetics.