Concentration and separation of aqueous solutions of Cu2+, Ni2+, Fe3+ by dextran

The effects of water-soluble polymers on the concentration and separation of the aqueous solutions of the metal ions have been studied. The separation of metal ions can be possible by ultrafiltration-complexation process. The effect of Dextran, which is a water-soluble polymer, on the concentration and separation of metal ions (Cu²⁺, Ni²⁺, Fe³⁺) have been investigated by using EC-PEG 4000 alloy membranes. The permeability of these membranes for metal ions has been rrecorded at constant pressure but different pH values. It has been notices that the highest water-permeable membrane is also permeable towards Cu²⁺ and Ni²⁺, but has shown a considerable retention for Fe³⁺ as a result of the hydrolysis of Fe³⁺. The retentions of metallic ions and metallic-ion-Dextran couples have been determined at constant pressure but different pH and polymer concentration values. It has been shown that Fe³⁺/Ni²⁺ and Fe³⁺/Cu²⁺ couples can be separated by using Dextran. © 1995 John Wiley & Sons, Inc.     

Selective separation of some heavy metals by poly(vinyl alcohol)‐grafted membranes

A poly(vinyl alcohol) membrane (PVA) was modified by radiation graft copolymerization of acrylic acid/styrene (AAc/Sty) comonomers. The Cu and Fe ion‐transport properties of these membranes were investigated using a diaphragm dialysis cell. In the feed solution containing CuCl₂ or a mixture of CuCl₂ and FeCl₃, the PVA‐g‐P(AAc/Sty) membranes showed high degrees of permselectivity toward Cu²⁺ rather than toward Fe³⁺. The permeation of Cu²⁺ ions through the membranes was found to increase with decrease in the grafting yield. However, as the content of Cu²⁺ ions in the Cu/Fe binary mixture feed solutions decreased, the rate and the amount of transported Cu²⁺ through the grafted membrane decreased, with no appreciable permselectivity toward Fe³⁺. When Fe²⁺ ions were used instead of Fe³⁺ ions in the feed solution containing Cu²⁺, the transport of both Cu²⁺ and Fe²⁺ through the membrane was observed. The rate of transport of Fe²⁺ was higher than that of Cu²⁺. In addition, it was found that the selective transport of ions was significantly influenced by the pH difference between both sides of the membranes. As the pH of the feed or the received solution decreased, both Cu²⁺ and Fe³⁺ passed through the membrane and were transported to the received solution. The role of carboxylic acid and the hydroxyl groups of the grafted membranes in the transportation process of ions is discussed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 125–132, 2000     

Concentration Effects on Separation Selectivity in Foam Fractionation

Abstract

Removal of cadmium, copper, and nickel ions from aqueous solution by foam fractionation has been studied using a chelating surfactant, 4-dodecyl-diethylenetriamine. The rate of removal is a function of concentration of both metallic ions and surfactant. In the low concentration range for the metallic ions compared to that of the surfactant, the order of removal was found to be Cd²⁺ > Ni²⁺ > Cu²⁺. However, at higher concentrations of ions, the order becomes inverse, Cu²⁺ > Ni²⁺ > Cd²⁺. A selectivity coefficient for the separation of a specified ion from one or more ions using a chelating surfactant is shown to be dependent on the surface tension of the complex and the chelation constants. The relationship between separation selectivity of the removal of the metallic ions and concentration of both surfactant and metallic ions is discussed     

Effect of metallic ions in photo-induced graft copolymerization onto cellulose

In photo-induced graft copolymerization of methyl methacrylate onto cellulose, the effect of metallic ions as sensitizer was investigated. Some metallic ions were effective in their adsorbed states and accelerated the formation of grafts in the order Fe²⁺ > Ag⁺ > Fe³⁺. However, Cu²⁺ acted negatively, and little effect was observed for Co²⁺, Ni²⁺, Mn²⁺, Zn²⁺, and Cr³⁺. In the systems in which aqueous metallic salt solutions were added, the formation of grafts was generally depressed, but Fe³⁺ was an exception. The effect of metallic ions on the scission reaction of cellulose main chains did not necessarily agree with the effect on the formation of grafts. This is attributed to the varied interaction between cellulose and the different active species produced by irradiation, depending on the type of metallic ions used.     

Chelating water-soluble polymers associated with ultrafiltration membranes for metal ion removal

This article describes the retention properties of commercial chelating water-soluble polymers, for different metal ions in aqueous solution using a liquid-phase polymer-based retention (LPR) technique. The polymers studied were poly(ethyleneimine) or P(EI) (water-free and a 50?% aqueous solution) and poly(ethyleneimine epichlorohydrin) or P(EIE) (a 17?% aqueous solution). These commercial polymers were fractionated by ultrafiltration membranes and then characterized by Fourier-transformed infrared spectroscopy. The extraction process was performed using the following metal ions: Cu²⁺, Cd²⁺, Co²⁺, Ni²⁺, Zn²⁺, Pb²⁺ and Cr³⁺. In the washing studies, we varied the pH (3, 5 and 7) and retention time. The results showed that P(EI) showed high retention for all the metal ions at pH 7 and for selective retention of Cu²⁺ at pH 5, while P(EIE) showed selective retention of Cu²⁺ ions at pH 7. Using the enrichment method, the maximum retention capacity of Cu²⁺ and Cd²⁺ was achieved using a 50?% aqueous solution of P(EI) at pH 5 and 7, respectively. Finally, charge–discharge experiments for Cu²⁺ were analysed by changing the pH from basic to acidic over three cycles. These results showed that it is possible to remove metal ions and regenerate the removal capacity of the polychelatogens using the LPR technique.     

Synthesis and study of the chelating properties of 3-carboxy-4-hydroxyacetophenone-formaldehyde resins

3-Carboxy-4-hydroxyacetophenone (CHAP) was polycondensed with various proportions of formaldehyde using alcoholic alkali as catalyst. The resin samples, designated as CHAP-F, have been characterized by elemental analyses and IR spectroscopy, by estimation of their number average molecular weights (M?_n), by measurement of intrinsic viscosity, and by TGA. Polymeric metal chelates of one CHAP-F sample with Cu²⁺, Fe³⁺, Co²⁺, Ni²⁺, and UO₂²⁺ ions have been prepared and characterized. Ion-exchanging properties of one CHAP-F resin sample for Fe³⁺, Cu²⁺, and Ni²⁺ metal ions are studied by the application of the batch-equilibration method.     

Influence of the Metal Ions Cr3+, Fe3+, Ni2+ and Cu2+ on the Stability and Oxygen Consumption of Acrylic and Methacrylic Acid

For the safe and trouble‐free operation of a manufacturing plant and the safe storage of acrylic, as well as methacrylic monomers, it is important to know the polymerization stability as a function of the process parameters (temperature, oxygen concentration, and impurities, e.g., metal ions). Contamination with metal ions can be caused by the corrosion of steel units. Therefore, the influence of the metal ions Cr³⁺, Fe³⁺, Ni²⁺ and Cu²⁺ in the concentration range of 0–10 ppm (g g^–1) on the polymerization behavior and the oxygen consumption of acrylic and methacrylic acid were examined in this work. It was shown that Cr³⁺, Ni²⁺, and Cu²⁺ ions extend the inhibition period of acrylic acid (AA) and methacrylic acid (MAA) and reduce the O₂ consumption. Fe³⁺ ions, however, cause a decrease of the inhibition period and in the case of AA an increase of the O₂ consumption, which leads, in the end, to a faster unintentional polymerization. Therefore, alloys which contain iron should be avoided as far as possible in the construction of AA plants. Fe³⁺‐ions show the opposite influence towards MAA, here the presence of Fe³⁺ shows a stabilizing effect.     

PVA cryogel membranes as a promising tool for the retention and separation of metal ions from aqueous solutions

The sorption and transport of metal ions by poly(vinyl alcohol) hydrogel membranes (PVA HG), obtained by physical crosslinking through the freezing/thawing method, was analyzed using aqueous nitrate solutions of copper, lead, and nickel, at concentrations ranging from 1 to 100 mM, at 25°C. The sorption of heavy metal by PVA HG has been characterized by swelling and loading degrees. The effect of the heavy metals incorporation on the chemical properties of PVA HG matrices has been studied using SEM, to observe changes in the surface morphology of PVA HG membranes, and FTIR–ATR, aiming to monitor the heavy metals ions sorption into PVA hydrogel membranes. The analysis of permeation and diffusion coefficients of 100 mM aqueous solutions of Cu²⁺, Ni²⁺, and Pb²⁺ show that the diffusion process may be mainly described by hydrodynamic models; however, the transport process shows that the distribution coefficient for the different heavy metals are always higher than one, in agreement, with the sorption studies. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Catalytic Ozonation of Citric Acid by Metallic Ions in Aqueous Solution

Ozonation of citric acid in water catalyzed by different ions from the first row of transition metals (Mn²⁺, Co²⁺, Ti⁴⁺, Fe²⁺, Cu²⁺, Ni²⁺ and Zn²⁺) was investigated at room temperature. The results showed that at pH=2, where the decomposition of citric acid is negligible by only ozone, the following order of efficiency of metallic ions for the decomposition of citric acid by ozone, and also for the TOC removal, was obtained: Mn²⁺ > Co²⁺ > Ti⁴⁺ > Fe²⁺. Cu²⁺, Ni²⁺ and Zn²⁺ showed negligible efficiency under the same experimental conditions. At pH=5.5, Mn²⁺ and Co²⁺ showed slightly higher efficiency than at pH=2 while Ti⁴⁺ and Fe²⁺ showed insignificant effect at this pH value. On the other hand, at pH=7 the investigated catalysts showed no obvious catalytic efficiency for the decomposition of citric acid by ozone.     

Sorption properties of the iminodiacetate ion exchange resin,amberlite IRC‐718, toward divalent metal ions

The sorption properties of the commercially available cationic exchange resin, Amberlite IRC‐718, that has the iminodiacetic acid functionality, toward the divalent metal‐ions, Fe²⁺, Cu²⁺, Zn²⁺, and Ni²⁺ were investigated by a batch equilibration technique at 25°C as a function of contact time, metal ion concentration, mass of resin used, and pH. Results of the study revealed that the resin exhibited higher capacities and a more pronounced adsorption toward Fe²⁺ and that the metal‐ion uptake follows the order: Fe²⁺ > Cu²⁺> Zn²⁺ >Ni²⁺. The adsorption and binding capacity of the resin toward the various metal ions investigated are discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Selective Extraction of Cu2+ and Ag+ Ions from Sulfuric Acid by Synergistic Combinations of Tetradentate Thia Macrocycles with Dioodecylnaphthalene Sulfonic Acid

Abstract

The aqueous-insoluble thia macrocycles tetrathia-14-crown-4 (TT14C4) and tetrathia-16-crown-4 (TT16C4) strongly and selectively synergize the extraction of Cu²⁺ and Ag⁺ ions from aqueous sulfuric acid solutions by the organophilic cation exchanger didodecylnaphthalene sulfonlc acid (HDDNS) in toluene diluent. Over a range of sulfuric acid concentrations, the selectivity is given by the order Ag² > Cu²⁺ > Mn²⁺, Fe²⁺, Fe³⁺, Co²⁺, Ni²⁺, and Zn²⁺, where synergism occurs only for Ag⁺ and Cu²⁺. Selectivity factors greater than 300 have been achieved for Cu²⁺ over ubiquitous Fe³⁺. The synergistic extraction of Cu²⁺ and Ag⁺ was explored as a function of sulfuric acid concentration, relative concentration of macrocycle vs. HDDNS, and loading.     

Synthesis of a polyacrylamide chelating resin and applications in metal ion extractions

A series of differently crosslinked polyacrylamide chelating resins were prepared, using N,N′-methylene-bis-acrylamide as the crosslinking agent. The crosslinked resins were functionalized by the reaction with ethylene diamine to get amino group capacities varying from 4.2 to 1.1 mequiv/g. The maximum adsorption capacities of the lightly crosslinked resin for Fe³⁺, Fe²⁺, Ni²⁺, and Cu²⁺ are 3.62, 4.22, 1.48, and 1.67 mequiv/g, respectively. The adsorbed metal ions can be quantitatively desorbed. The adsorption rate and the influence of pH on the adsorption of metal ions were examined. The resins can be used for the separation between different metal ions as well as the ions in different valence states (e.g., Fe³⁺ and Fe²⁺). The resin is amenable for continuous process and can be regenerated several times.     

Methanol-Water Solution Transport in Nafion Membranes with Different Cationic Forms

Measurements of liquid transport were made with a Nafion membrane at different cationic forms. The experimental data are used to estimate the alcohol permeability when the membrane is separating water and water-methanol solutions. The obtained permeability coefficient values were useful for analyzing the influence of the substituted cations on the transport process in the membranes. In the present article, the permeability coefficient of methanol in Nafion substituted by Na⁺, K⁺, Cs⁺, Mg²⁺, Ca²⁺, Ba²⁺, Fe²⁺, Fe³⁺, and Al³⁺ were reported at different methanol concentration values. The analysis of the results revealed that, in general, for ions with the same period in the periodic table, the alcohol permeability decreases with increasing the valence. In contrast, when ions with the same valence are compared, the alcohol permeability decreases when the atomic mass increases, with the exception of the Mg²⁺. As a general trend, similar alcohol permeability variation with the concentration is observed for all the cationic forms of the membrane. There is an initial increase in the permeability, and, when the methanol concentration in the solutions is about 60%, the permeability decreases with the alcohol concentration. However, in the case of trivalent ions, the methanol permeability decreases with the methanol concentration.     

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.     

Nickel(II)‐imprinted monolithic columns for selective nickel recognition

Ni²⁺‐imprinted monolithic column was prepared for the removal of nickel ions from aqueous solutions. N‐Methacryloyl‐L ‐histidine was used as a complexing monomer for Ni²⁺ ions in the preparation of the Ni²⁺‐imprinted monolithic column. The Ni²⁺‐imprinted poly(hydroxyethyl methacrylate‐N‐methacryloyl‐L ‐histidine) (PHEMAH) monolithic column was synthesized by bulk polymerization. The template ion (Ni²⁺) was removed with a 4‐(2‐pyridylazo) resorcinol (PAR):NH₃? NH₄Cl solution. The water‐uptake ratio of the PHEMAH–Ni²⁺ monolith increased compared with PHEMAH because of the formation of nickel‐ion cavities in the polymer structure. The adsorption of Ni²⁺ ions on both the PHEMAH–Ni²⁺ and PHEMAH monoliths were studied. The maximum adsorption capacity was 0.211 mg/g for the PHEMAH–Ni²⁺ monolith. Fe³⁺, Cu²⁺, and Zn²⁺ ions were used as competitive species in the selectivity experiments. The PHEMAH–Ni²⁺ monolithic column was 268.8, 25.5, and 10.4 times more selective than the PHEMAH monolithic column for the Zn²⁺, Cu²⁺, and Fe³⁺ ions, respectively. The PHEMAH–Ni²⁺ monolithic column could be used repeatedly without a decrease in the Ni²⁺ adsorption capacity. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Use of super absorbent hydrogels derivative from acrylamide with itaconic acid and itaconates to remove metal ions from aqueous solutions

Poly(acrylamide-co-itaconic acid) (AAm/IA) and poly(acrylamide-co-monomethoxyethyl itaconate) (AAm/MEI) hydrogels (HGs) synthesized at different molar ratios were used to study the adsorption of some metal ions as Cu²⁺, Ni²⁺, Pb²⁺, Cd²⁺, and Fe³⁺ in aqueous solutions at different concentration: 10, 50, 100, 500, and 1000 mg L⁻¹. Statistical analysis was performed and the effect of the metal ion, ion concentration, and hydrogel (HG) composition, on adsorption and adsorption efficiency, was evaluated for both HGs studied (AAm/IA and AAm/MEI) and each factor gave rise to significant differences (P ≤ 0.05). The adsorption depends on the type of ion, its concentration, and also influenced by the type and composition of the HGs. For each system the adsorption efficiencies for all ions were similar with exception of Fe³⁺, which showed the highest adsorption efficiency in AAm/MEI HG, but the less for the AAm/IA. For both systems, the maximum adsorption efficiency was observed when the molar ratio AAm/IA or AAm/MEI is 80/20. When the adsorption was carried out with individual ions, AAm/MEI HG was more efficient than AAm/IA. For a multielement sample of Cu²⁺, Ni²⁺, Pb²⁺, and Cd²⁺, both HGs could adsorb all the ions and their behavioral trend was the same in both cases, in which the adsorption efficiency was Pb²⁺ > Cu²⁺ > Cd²⁺ > Ni²⁺. The results of the statistical analysis evidence the advantage of its use in this type of studies. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46999     

Preparation of graphene oxide/carboxymethyl chitosan/polyvinyl alcohol composite nanofiber membranes by electrospinning for heavy metal adsorption

In this paper, a graphene-oxide/carboxymethyl-chitosan/polyvinyl-alcohol (GO/CMC/PVA) composite nanofiber membrane was prepared by electrospinning and cross-linking with glutaraldehyde (GA) to improve the water resistance. The composite nanofiber membrane can be used in the field of heavy metal adsorption. The membrane was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. The effects of GO concentration, adsorption time, and initial concentration of heavy-metal ion (Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺) solution on the adsorption performance of the fiber membranes were investigated. The results showed that the addition of GO can reduce the diameter of nanofibers. GO, CMC, and PVA exhibited good compatibility, and the intermolecular hydrogen bonding improved. The addition of GO also improved the crystalline properties of the composite fiber membrane. In the optimal cross-linking condition, GA was saturated by steam cross-linking for 6 h. The introduction of GO improved the adsorption capacity of the membrane for heavy metals in water. The utmost adsorption capacities for Ni²⁺, Cu²⁺, Ag⁺, and Pb²⁺ were 262.1, 237.9, 319.3, and 413.6 mg/g when using the cross-linked composite fiber membranes, respectively. The results of adsorption kinetics and thermodynamics showed that the adsorption process accorded with the pseudo-second-order kinetic model and Langmuir–Freundlich isotherm model.     

Chelation ion‐exchange properties of copolymer resin derived from 4‐hydroxyacetophenone,oxamide, and formaldehyde

A copolymer (4‐HAOF) prepared by condensation of 4‐hydroxyacetophenone and oxamide with formaldehyde in the presence of an acid catalyst proved to be a selective chelating ion‐exchange copolymer for certain metals. Chelating ion‐exchange properties of this copolymer were studied for Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, and Hg²⁺ ions. A batch equilibrium method was employed in the study of the selectivity of metal‐ion uptake involving the measurements of the 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 and in media of various ionic strengths. The copolymer showed a higher selectivity for Fe³⁺ ions than for Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺, Cu²⁺, Ni²⁺, and Hg²⁺ ions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 787–790, 2003     

Synthesis of resin IV: Salicylic acid,diaminonaphthalein, and formaldehyde terpolymer and its ion exchange

This article reports the synthesis, characterization, and ion exchange properties of a terpolymer. The terpolymer resin salicylic acid‐diaminonaphthalein‐formaldehyde (SDNF) was synthesized by the condensation of salicylic acid and diaminonaphthalein with formaldehyde in the presence of a hydrochloric acid catalyst. Terpolymer resin was characterized by elemental analysis, infrared (IR) spectroscopy, nuclear magnetic resonance spectroscopy, and UV–Visible spectral studies. The number average molecular weight of the resin was determined by nonaqueous conductometric titration. Chelation ion exchange properties have also been studied for Fe³⁺, Cu²⁺, Ni²⁺, Co²⁺, Zn²⁺, Cd²⁺, Pb²⁺ ions employing a batch equilibrium method. It was employed to study the selectivity of metal ion uptake involving the measurements of distribution of a given metal ion between the polymer sample and a solution containing the metal ion. The study was carried out over wide pH range and in a media of various ionic strengths. The terpolymer showed higher selectivity for Fe³⁺, Cu²⁺, and Ni²⁺ions than for Co²⁺, Zn²⁺, Cd²⁺, and Pb²⁺ ions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis,characterization, metal sorption,and biological activity of poly(N‐heterocylic acrylamide)

N‐heterocyclic acrylamide monomers were prepared and then transferred to the corresponding polymers to be used as an efficient chelating agent. Polymers reacted with metal nitrate salts (Cu²⁺, Pb²⁺_, Mg²⁺, Cd²⁺, Ni²⁺, Co²⁺_, Fe²⁺) at 150°C to give metal‐polymer complexes. The selectivity of the metal ions using prepared polymers from an aqueous mixture containing different metal ion sreflected that the polymer having thiazolyl moiety more selective than that containing imidazolyl or pyridinyl moieties. Ion selectivity of poly[N‐(benzo[d]thiazol‐2‐yl)acrylamide] showed higher selectivity to many ions e.g. Fe³⁺, Pb²⁺, Cd²⁺, Ni²⁺, and Cu²⁺. While, that of poly[N‐(pyridin‐4‐yl)acrylamide] is found to be high selective to Fe³⁺ and Cu²⁺ only. Energy dispersive spectroscopy measurements, morphology of the polymers and their metallopolymer complexes, thermal analysis and antimicrobial activity were studied. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42712.