Syntheses and properties of carboxymethyl chitosan/urea–formaldehyde snake‐cage resins

A series of novel snake‐cage resins were synthesized using carboxymethyl chitosan (CM‐CTS) as the snake resin and urea–formaldehyde resin (UF) as the cage resin. Such factors as the optimal synthesis conditions, content of the crosslinking agent, and sorption capacities for metal ions of the above‐mentioned resins were investigated. The experimental results show that these resins have appropriate swelling properties and good mechanical stability. They do not run off in water, HCl, and NaOH aqueous solutions. To form a stable network system, NH₄Cl was used as a crosslinking agent to crosslink urea and formaldehyde in synthesis. The sorption experiment showed that the sorption properties of the resins in the presence of the crosslinking agent NH₄Cl are better than those without a crosslinking agent. The investigation of the FTIR spectra indicated that the chelate groups, such as —OH, —CO and NHCH₂CO, in snake‐resin molecules participated in the coordination with the metal ions, but the —C?O bonds in the cage resin UF did not. The snake resin CM‐CTS in the snake‐cage resins was the major contributor of sorption. The sorption dynamics showed that the sorption was controlled by liquid film diffusion. The isotherms can be described by Freundlich and Langmuir equations. The saturated sorption capacities of the resins for Cu²⁺, Ni²⁺, Zn²⁺, and Pb²⁺ were 1.48, 0.78, 0.13, and 0.02 mmol g^?1, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 310–317, 2002; DOI 10.1002/app.10331     

Macroporous polymeric ion exchangers as adsorbents for the removal of cationic dye basic blue 9 from aqueous solutions

Two macroporous cation‐exchange resins, Purolite C145, a strongly acidic cation macroporous resin, and Purolite C107E, a weakly acidic cation‐exchange resin, were used to remove the dye Basic Blue 9 (BB9) from an aqueous medium. Batch adsorption experiments were carried out to analyze the effect of various parameters, such as the phase contact time, initial dye concentration, initial solution pH, resin dose, and temperature. The experimental equilibrium data were evaluated by the Langmuir, Freundlich, and Dubinin–Radushkevich (DR) adsorption models. The Freundlich model better described the adsorption processes of the BB9 dye onto both cation exchangers, and the monolayer adsorption capacities were established as 31.9846 mg/g (C145) and 27.77 mg/g (C107E) at 20°C. The values of the mean free adsorption energy (E) obtained from the DR model suggested a porous structure of the adsorbents and proposed ion exchange at the main mechanism of the adsorption process. The values of the thermodynamic parameters showed that the retention of the cationic dye was a spontaneous and endothermic process. Environmental scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize the sorbent and also to validate the adsorption mechanism as ion‐exchange ones. The desorption experiments by a batch method were performed with different solutions: 0.1 and 1 mol/L HCl, 2.5 mol/L H₂SO₄, CH₃OH, and a mixture between 1 mol/L HCl and CH₃OH. Desorption performed with sulfuric acid was shown to be most effective because more than 85% of the adsorbed dye was removed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39620.     

Cr(VI)‐containing wastewater treatment by means of ion exchange on weak‐ and strong‐base anion exchangers

The aim of this research work was a thermodynamic and kinetic study of the retention of Cr(VI) ions from a K₂CrO₄ solution on macroporous weak‐ and strong‐base anion exchangers, Lewatit M 64 A and Lewatit MP 500 A, respectively. Also, the correlations among the ion‐exchange rate, the retention capacity of Cr(VI), and some process parameters were established. The parameters studied mainly were the concentration of Cr(VI) ions and the type of the counterions coupled with active groups from the anion exchangers. The results led to the conclusion that, for the Lewatit M 64 A resin, there is the following order of the Cr(VI) retention capacity: RCl > R₂SO₄ > ROH, while for the strong‐base anion exchanger, the retention capacity for the Cr(VI) ions is different: ROH > RCl > R₂SO₄. In the Cl^? form, both anion exchangers have the same retention‐capacity values. On the other side, the weak‐base anion exchanger in SO and OH^? forms presents the lowest retention‐capacity values. The process kinetics also presents some differences: for the Lewatit M 64 A resin, the ion‐exchange rate has lower values, especially in the OH^? form. This result is attributed to the increase of the OH^? ion concentration in the solution and its presence hinders the dissociation of the active groups of a weak‐base anion exchanger. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2093–2098, 2002     

Sorption equilibrium of Cr(VI) ions by strong base anion exchangers with pyridine structures

Chromate sorption on pyridine strong base anion exchangers with different functional groups (methyl, ethyl, and butyl groups), at the quaternary nitrogen atoms, was studied as a function of various initial concentrations (100–1500 mg Cr/L) and counterion type. The studied resins in the Cl^?[ form have higher Cr(VI)‐retention capacities than those in the SO form. The pyridine strong base anion exchangers showed a selectivity reversal for the sulfate and chromate anions compared to that of the commercial resins. The alkyl substituent length of the quaternary nitrogen atoms exerted a substantial influence on the Cr(VI)‐retention capacity values for the resins in the Cl^? form; the chromate anions preferred resins with methyl functional groups, that is, resins with a greater hydrophilic structure. For the resins in the SO form the length of the substituent at the quaternary nitrogen atom had only a negligible influence on their Cr(VI)‐retention values. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1957–1963, 2004     

Preconcentration and Determination of Pb (II) in Aqueous Samples using Functionalized Dowex 1X8

Synthetic resin Dowex 1X8 was functionalized with α-Nitroso β-Naphthol (Dowex-αNβN) and with 8-Hydroxy Quinoline (Dowex-8HQ) to form chelating resin. The resultant chelating resins were characterized using scanning electron microscopy (SEM), thermo gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The efficiency of these resins for the removal/preconcentration of Pb (II) from aqueous samples was evaluated. Optimum conditions of pH, time of equilibrium, and sample volume were investigated for maximum retention of Pb (II) from aqueous solutions. At optimum conditions, 100% adsorption was observed for the functionalized resins. Both Freundlich and Langmuir isotherms were applied to the adsorption data and it was observed that data fits well to Langmuir isotherm. Various parameters such as shaking time, type, and concentration of eluents were investigated for the recovery of Pb (II) from the chelating resins. For Dowex-αNβN and Dowex-8HQ, 100% recovery with a preconcentration factor of 100 was achieved with 0.5 and 2 M HCl, respectively. The selectivity and specificity of the functionalized resins was also evaluated by studying the effect of various foreign ions and the results have been compared with the unmodified Dowex.     

Functionalization in copolymers based on 4VP:DVB for the removal of Cr(VI) ions from aqueous solution

Adsorption capacity for Cr(VI) ions has been evaluated on two ion‐exchange resins. A gel‐type precursor resin was obtained by suspension polymerization of 4‐vinylpyridine and divinylbenzene monomers with 40% crosslinking degree. It was quaternized with different functional groups to give two ion‐exchange resins. The R2 resin contained sulfobetaine groups, and R3 methyl groups. The resins were characterized by Fourier transform infrared and solid‐state ¹³C CP/MAS NMR spectroscopy and by elemental analysis. An adsorption experiment was carried out by a batch equilibrium procedure. Langmuir and Freundlich isotherm models were used to determine the adsorption capacity. R2 and R3 resins exhibited maximum adsorption capacity q_max = 75.8 and 56.2 mg/g, respectively. The resins achieve equilibrium in 60 min. The R3 and R2 resins showed a retention capacity of 95% and 80% for the Cr(VI) ions, respectively. The behaviors of both resins were explained well by a pseudo‐second‐order kinetics model. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45548.     

Palladium Recovery from Dilute Effluents using Biopolymer‐Immobilized Extractant

Abstract

Cyanex 301‐immobilized material (prepared by immobilization into an alginate matrix) was tested for Pd sorption in 1 M HCl solutions with a special attention to sorption isotherms and uptake kinetics. This immobilized extractant had great affinity for Pd, as shown by the initial slope of the sorption isotherms. Sorption capacities as high as 150 mg Pd g^?1 were obtained in 1 M HCl solutions. However, kinetics was slow, compared to conventional resins. The main limiting step in the process is the diffusion of metal ions into the matrix. The influence of parameters such as HCl concentration, NaCl addition, presence of Pt (as a competitor metal) has been checked. It appeared that sorption performance of Cyanex 301‐immobilized material was hardly influenced by the addition of NaCl and by HCl concentration (below 2.5 M). The resin was remarkably selective for Pd, versus Pt, especially at 1 M HCl concentration. Loaded resins can be desorbed using thiourea solutions.     

Piperazine Functionalized Resins for Au(III), Pt(IV), and Pd(II) Sorption

The result of synthesis of anion exchangers bearing piperazine functionalities is presented in this paper. A series of new ion exchange resins was synthesized by modification of VBC/DVB copolymer with 1(2-aminoethyl)piperazine (resin 1P), 1-amino-4-methylpiperazine (resin 2P), and 1-methylpiperazine (resin 3P). Adsorption studies of gold, platinum, and palladium were conducted with batch and dynamic method from multicomponent solutions containing AuCl₄^?, PtCl₆^2?, and PdCl₄^2? in the concentration range 10 mg/dm³ to 919 mg/dm³. The resins revealed excellent sorption ability towards these metals. The greatest total sorption capacities were determined as 331 mg/g Au for 2P resin, 405 mg/g Pt for 3P resin, and 150 mg/g Pd for 1P resin. The examined 3P resin showed the best total sorption capacity 796 mg/g. Affinity studies were also conducted. The examined resin 1P revealed the greatest affinity to platinum and palladium (lgK 4.5-5) whereas resin 2P revealed the best affinity to gold where lgK were ca. 4.9.     

THE INFLUENCE OF CROSSLINKAGE ON THE DISTRIBUTION COEFFICIENTS AND ANION EXCHANGE BEHAVIOUR OF SOME ELEMENTS IN HYDROCHLORIC ACID

Equilibrium distribution coefficients are presented for Cu(II), Zn(II), Cd(II), Fe(III), Ga(III), In(III), Th(IV) and U(VI) on the strongly basic anion exchangers AG1-X2, AG1-X4, AG1-X8, AG1-X10 and AG MP-1 in hydrochloric acid. Coefficients generally increase with increase in crosslinkage, while exchange kinetics show a marked improvement with decrease in crosslinkage. Elution curves for some elements on the lower crosslinked resins AG1-X2 and AG1-X4 and on the macroporous resin AG MP-1 demonstrate the advantages of these resins for some separations.     

Synthesis and characterization of polystyrene‐supported glucosamine resin and its adsorption behavior for Au(III)

A novel chelating resin, crosslinking polystyrene‐supported glucosamine (PS‐GA), was prepared and its structure was confirmed by FTIR, elemental analysis, and X‐ray photoelectron spectroscopy. The adsorption properties of PS‐GA for Au(III) were investigated. PS‐GA resin possessed excellent enriching property to Au(III) ions and adsorption proportion E% could reach to about 90 shortly after 3 h. The adsorption dynamics of Au(III) showed that the adsorption was controlled by liquid film diffusion and the apparent activation energy E_a was 12.91 kJ mol^?1. Both Langmuir model and Freundlich model could describe the isothermal process of Au(III), and ΔG, ΔH, ΔS values were calculated. The mechanism of adsorption for Au(III) was confirmed by FTIR, SEM, and XPS. The results showed that redox reaction occurred and both coordination and ion‐exchange existed simultaneously in the adsorption. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4581–4586, 2006     

A Convenient Approach Toward Fluoride Sorption by Calix[4]arene Based Sorbent

The present study describes the sorption of fluoride on a potential and newly synthesized p-tetraaminocalix[4]arene based resin (p-TAC4 resin). The p-TAC4 resin was synthesized via immobilization of p-tetranitrocalix[4]arene (p-TNC4) onto the Merrifield resin followed by catalytic reduction with SnCl₂/EtOH/HCl. The p-TNC4 and p-TAC4 resins were characterized using FT-IR, elemental analysis, and scanning electron microscopy (SEM). Fluoride removal capability from the aqueous media of the p-TAC4 resin has been evaluated through batch sorption study. The effect of pH, sorbate concentration, sorbent dosage, and contact time on fluoride removal was evaluated. The Langmuir (L), Freundlich (F), and Dubinin–Radushkevich (D-R) isotherms revealed that the fluoride on p-TAC4 resin follows physiosorption mechanism. All the results support and emphasize that the p-TAC4 resin is an effective sorbent for the removal of fluoride from the aqueous environment at a wide range of pH. The study may confer its impact on human health, reinstate polluted sites and other fields such as analytical, clinical, as well as material sciences.     

Gold Recovery from HCl Solutions using Cyphos IL‐101 (a Quaternary Phosphonium Ionic Liquid) Immobilized in Biopolymer Capsules

Tetraalkyl phosphonium chloride (Cyphos IL‐101), an ionic liquid (IL), was tested for gold recovery from HCl solutions: first in liquid/liquid extraction systems (using toluene and hexane as solvent) and in a second step, after being immobilized in a biopolymer composite matrix. SEM‐EDAX analysis was used for the characterization of the resins. The sorption capacity reached up to 140 mg Au(III) g^?1 in 1 M HCl solutions. Base metals that do not form anionic chlorocomplexes and nitrate or chloride ions (at 5 g L^?1) did not interfere with Au(III) binding. Gold binding probably occurs through the interaction of R₃R'P⁺ with AuCl₄ ^?. The kinetics of sorption was carried out varying agitation speed, metal concentration, IL content, and resin drying. Intraparticle diffusion played an important role on the control of sorption kinetics. Gold could be desorbed from the loaded IL‐impregnated resin using thiourea (in HCl solutions). The resin could be re‐used for at least 4 cycles. The resins are specially adapted for the recovery of gold from low metal concentrations.     

Preparative Enrichment and Separation of Glycyrrhetinic Acid Monoglucuronide from Fermentation Broths with Macroporous Resins

Preparative enrichment and separation of Glycyrrhetinic acid monoglucuronide (GAMG) from the pretreated fermentation broth of glycyrrhizin was studied by using six macroporous resins with different physical and chemical properties. D101 resin showed the maximum effectiveness among the tested resins. The solute affinity towards D101 resin at different temperatures was described in terms of Langmuir and Freundlich isotherms, and the equilibrium experimental data were well-fitted to the two isotherms. The dynamic adsorption and desorption tests were carried out in order to optimize the operational parameters for the efficient separation of GAMG. After one run treatment with D101 resin, the contents of GAMG in the product were increased to 8.2-fold with recovery yields of 93.3%. The process achieved easy and effective enrichment and separation of GAMG with D101 resin, and it could be applied for the large-scale preparation of GAMG from the fermentation broth of glycyrrhizin.     

Adsorption of BSA on DEAE-Dextran: Equilibria

Abstract

Equilibrium isotherms for adsorption of BSA on DEAE-dextran have been determined experimentally. They were little affected by the initial concentration of BSA but were considerably affected by pH. They were correlated by the Langmuir equation when pH ≥ 5.05 and by the Freundlich equation at pH 4.8 (≈ pI). The maximum amounts of inorganic anion exchanged for BSA were 1 and 0.4% of the exchange capacity of the ion exchanger at pH 6.9 and 4.8, respectively. When NaCl coexisted in the solution, the shape of the isotherm was similar to the Langmuir isotherm but was shifted to the right. When the concentration of NaCl was 200 mol/m³, BSA was not adsorbed on the resin. When BSA was dissolved in pure water, the saturation capacity of BSA on HPO₄ ^2? -form resin was about 3.5 times larger than that with buffer (pH 6.9). The amount of BSA adsorbed on univalent-form resin decreased when the liquid-phase equilibrium concentration of BSA was increased.     

Synthesis and characterization of sulphanilic acid–dithiooxamide–formaldehyde terpolymer resin for adsorption of nickel ions from waste water

A new chelating terpolymer resin of sulphanilic acid–dithiooxamide–formaldehyde (SDTOF) was synthesized. Dithiooxamide–formaldehyde (DTOF) was prepared by the reaction of dithiooxamide and formaldehyde. These resins were characterized using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, and scanning electron microscopy. Chelating resins beads were applied for adsorption of nickel (II) ions by batch and column techniques. Sorption experiments were performed by varying pH, agitation time, sorbent dosage and initial concentration of nickel (II) ion solution. SDTOF and DTOF resins showed adsorption capacity of 188.3 and 99.8 mg g^?1, respectively. Nickel adsorption isotherms data were fitted to Langmuir isotherm. Kinetic studies showed the adsorption process followed pseudosecond‐order rate model. Desorption of Ni(II) ions was done using 0.1 M HCl, HNO₃, and ethylenediamine tetraacetic acid solutions. The reusability of SDTOF and DTOF resins for the removal of Ni(II) ions was also determined after 10 sorption?desorption cycles. POLYM. ENG. SCI., 55:163–172, 2015. © 2014 Society of Plastics Engineers     

Synthesis and analytical application of a chelating resin based on a crosslinked styrene/maleic acid copolymer for the extraction of trace‐metal ions

A new chelating polymer sorbent was synthesized through the copolymerization of styrene and maleic anhydride in the presence of divinyl benzene as the crosslinking agent, followed by hydrolysis. This polymeric resin, bearing O donor groups, had the advantage of being stable in basic and saline media, unlike its linear analogue. This newly developed chelating matrix has a high resin capacity for metal ions such as Cr, Fe, Ni, Cu, and Pb. Various physicochemical parameters, such as the pH, volume, and flow rate, and the interference effect on metal uptake were studied. The sorption capacities of the crosslinked resin for Cr(III), Fe(III), Ni(II), Cu(II), and Pb(II) were 10.2, 14.3, 14.2, 15.4, and 8.8 mg/g, respectively. A high recovery of 98% was obtained for all the metal ions with 2N HCl as the eluting agent. The chelating resin was characterized by swelling studies, Fourier transform infrared, elemental analysis, X‐ray studies, and thermal analysis. The Langmuir and Freundlich adsorption isotherms were used to validate the metal‐uptake data. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1771–1779, 2004     

Metal ion retention properties of poly(acrylic acid) and poly[N‐3‐(dimethylamino)propyl acrylamide‐co‐acrylic acid]

The crosslinked resins poly(acrylic acid) (PAA) and poly[N‐3‐(dimethylamino)propyl acrylamide‐co‐acrylic acid] [P(NDAPA‐co‐AA)] are obtained by radical polymerization and characterized by FTIR spectroscopy. PAA at basic pH exists basically as an acrylate anion that may contain end carboxylate groups or form bridges acting as mono‐ or bidentate ligands. P(NDAPA‐co‐AA) presents three potential ligand groups in its structure: carboxylic acid, amide, and amine. The trace metal ion retention properties of these two resins is compared by using the batch equilibrium procedure. The metal ions are contained in saline aqueous solutions and are found in natural seawater. The retention of Cu(II), Pb(II), Cd(II), and Ni(II) metal ions is studied under competitive and noncompetitive conditions. The effects on the pH, contact time, amount of adsorbent, temperature, and salinity are investigated. The PAA resin presents a high affinity (>80%) for Cu(II) and Cd(II) ions. The P(NDAPA‐co‐AA) resin shows a high affinity for Pb(II) and Cd(II) ions. With 4M HNO₃ it is possible to completely recover the PAA resin charged with Cu(II) ions and the P(NDAPA‐co‐AA) resin charged with Pb(II) ions. The two resins show a high affinity for Cd(II) ions from the seawater containing Cu(II) and Cd(II) ions. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1385–1394, 2005     

Adsorption ability of oxidized multiwalled carbon nanotubes towards aqueous Ce(III) and Sm(III)

The aim of the present work was to investigate the adsorption of Ce(III) and Sm(III) onto multiwalled carbon nanotubes (MWCNTs) oxidized with concentrate nitric acid. The effects of solution pH, adsorbent dosage, and contact time were studied by batch technique. Langmuir, Freundlich and D-R isotherms were used to describe the adsorption behavior of Ce(III) and Sm(III) by oxidized MWCNTs, and the experimental results fitted Freundlich model well. The maximum uptake capacities (q _m ) calculated by applying the Langmuir equation for samarium and cerium ions were found to be 89.28 and 92.59 (mg/g), respectively. A comparison of the kinetic models and the overall experimental data was best fitted by the pseudo second-order kinetic model. The calculated thermodynamic parameters (ΔG^o, ΔH^o, and ΔS^o) showed that the adsorption for Ce(III) and Sm(III) is feasible, spontaneous and exothermic at 30–60 °C. Moreover, more than 70% of Ce(III) and Sm(III) adsorbed onto Oxidized MWCNTs could be desorbed with HNO₃.     

Gold(III) ions sorption on sulfur-containing polymeric sorbent based on 2,2‘-thiobisethanol dimethacrylate

ABSTRACT

Studies of gold(III) ions sorption from hydrochloric acid solutions on 2,2‘-thiobisethanol dimethacrylate/ethylene glycol dimethacrylate copolymer were performed. The correlation between the concentration of HCl (0.0001–4 M) and sorption efficiency (370–140 mg g^?1) was observed. The kinetics of sorption and the parameters of Langmuir and Freundlich isotherms for the studied systems were determined. The use of 0.8 M thiourea in 3 M HCl as eluent assured the high recovery degree of sorbed ions. It can, therefore, be concluded that newly synthesized sulfur-containing sorbent can be used in the recovery and concentration of gold(III) ions.     

Syntheses and adsorption properties for Hg2+ of chelating resin of crosslinked polystyrene‐supported 2,5‐dimercapto‐1,3,4‐thiodiazole

A novel chelating resin with functional group containing S and N atoms was prepared using chloromethylated polystyrene and 2,5‐dimercapto‐1,3,4‐thiodiazole (also called bismuththiol I, BMT) as materials. Its structure was characterized by infrared spectra and elementary analysis. The results showed that the content of the functional group was 2.07 mmol BMT g^?1 resin, 47% of which were in the form of monosubstitution (PS‐BMT‐1) and 53% in the form of double substitution (PS‐BMT‐2). The adsorption for mercury ion was investigated. The adsorption dynamics showed that the adsorption was controlled by liquid film diffusion. Increasing the temperature was beneficial to adsorption. The Langmuir model was much better than the Freundlich model to describe the isothermal process. The adsorption activation energy (E_a), ΔG, ΔH, and ΔS values calculated were 18.56 kJ·mol^?1, ‐5.99 kJ·mol^?1, 16.38 kJ·mol^?1, and 37.36, J·mol^?1·K^?1, respectively. The chelating resin could be easily regenerated by 2% thiourea in 0.1 mol·L^?1 HCl with higher effectiveness. Five adsorption–desorption cycles demonstrated that this resin was suitable for repeated use without considerable change in adsorption capacity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1646–1652, 2004