Performance of anion exchangers based on aniline,epichlorohydrin, and polyamines in sorption of molybdenum(VI) ions

Polyfunctional anion exchangers based on aniline, epichlorohydrin, and some polyamines were synthesized. The composition and structure of the anion exchangers were studied by IR spectroscopy and elemental analysis. Molybdenum sorption was studied by classical polarography, and dependences of the sorption of molybdenum(VI) ions on the solution acidity, concentration of metal ions, and time of contact of the resins with the Na₂MoO₄ solution were determined in batch experiments. These ion exchangers exhibit high performance in sorption of molybdenum ions. The developed sorbents with increased sorption ability can successfully solve problems of removing molybdenum(VI) ions from process effluents in nonferrous metallurgy.     

Potentialities of fibrous ion-exchange materials in the determination of sulfate ions by color reactions of barium with organic reagents on a solid phase

The possibility of the determination of sulfate ions with the use of fibrous materials filled with ion exchangers on the basis of color reactions of barium with the organic reagents Arsenazo III, Orthanilic B, and Orthanilic K on a solid phase was examined. A polyacrylonitrile fiber filled the cation exchanger KU-2; anion exchangers AB-17, A-5, ANKF-211, and EDE-10p; and polyampholyte ANKB-50 (PANV-ANKB-50) was used as the support. The study of the different techniques of the sorption of the reaction components demonstrated the efficiency of the two systems involving PANV-ANKB-50. The determination of sulfates is possible because of the sorption of the excess barium remaining after the reaction with sulfate ions in the solution and its detection on the solid phase with a solution of Arsenazo III or the detection of the excess barium remaining after the interaction with the solution of sulfate ions on the solid phase with a solution of Orthanilic K. The calibration plots are linear in the concentration range of sulfate ions 10^?4–10^?5 M.     

Comparison of Fibrous Carboxylic Ion Exchangers in Water Treatment to Remove Heavy Metal Ions

Treatment of drinking water to remove heavy metal ions Pb^{2 +}, Cu^{2 +}, Cd^{2 +}, Co^{2 +}, Ni^{2 +}, and Zn^{2 +} with commercial fibrous carboxylic ion exchangers FIBAN Kh-1, K-3, K-4, and K-5 was studied. Features of metal ion sorption from two-component solutions were determined. A comparative evaluation of the sorption selectivity of FIBAN fibrous ion exchangers with respect to heavy metal ions was made.     

Sorption of Nickel Ions from Aqueous Solutions by Ion Exchangers

Sorption of Ni²⁺ions from aqueous solutions by ion exchangers differed in their chemical nature and structure was studied. Based on the endothermic curves of ice melting obtained by a differential scanning calorimetry, the amounts of freezing and non-freezing water present in free volumes (pores) of the studied ion exchangers were calculated. Comparison of results obtained from the kinetic curves of nickel ion sorption with data on differential scanning calorimetry indicates a role of structural factor in the sorption of nickel ions. It was found that, depending on the total amount of freezing and non-freezing water, the KU-2-8 sulfonated cationite is the most preferable ion exchanger for the sorption of nickel ions from aqueous solutions. Therefore, sorbent efficiency in this case is determined by its structure rather than by chemical nature.     

Sorption properties of new nitrogen-containing wood-based ion exchangers with respect to gold(III) ions

Sorption properties of new nitrogen-containing wood-based ion exchangers with respect to gold(III) ions were examined in relation to the metal ion concentration in solution, pH of medium, and sorption temperature and time. The rate-limiting steps in the process were identified. The mechanism of sorption of aurate ions from solutions was considered in relation to their acidity.     

Ion-exchange recovery of nickel(II) and cobalt(II) from sulfuric acid solutions

Sorption recovery of nickel(II) and cobalt(II) in their joint presence in sulfuric acid solutions was studied on new samples of domestic ion exchangers of CYBBER brand. It was shown that the ion exchangers under study have a high sorption capacity for ions of both nonferrous metals, depending on the structure of a sorbent and on the acidity of a contacting solution. It was found that, after Co(II) and Ni(II) ions are extracted from weak or strong sulfuric acid solutions, they can be effectively eluted from the ion exchangers under study with a 2 M hydrochloric acid solution to an extent of 85–95% (nickel) and 87–95% (cobalt).     

Preparation of Sorbents Containing Straetlingite Phase from Zeolitic By-Product and Their Performance for Ammonium Ion Removal

In this study, straetlingite-based sorbents were used for NH₄⁺ ion removal from a synthetic aqueous solution and from the wastewater of an open recirculation African catfish farming system. This study was performed using column experiments with four different filtration rates (2, 5, 10, and 15 mL/min). It was determined that breakthrough points and sorption capacity could be affected by several parameters such as flow rate and mineral composition of sorption materials. In the synthetic aqueous solution, NH₄⁺ removal reached the highest sorption capacity, i.e., 0.341 mg/g with the S30 sorbent at a filtration rate of 10 mL/min and an initial concentration of 10 mg/L of NH₄⁺ ions. It is important to emphasize that, in this case, the Ce/C0 ratio of 0.9 was not reached after 420 min of sorption. It was also determined that the NH₄⁺ sorption capacity was influenced by phosphorus. In the wastewater, the NH₄⁺ sorption capacity was almost seven times lower than that in the synthetic aqueous solution. However, it should be highlighted that the P sorption capacity reached 0.512 mg/g. According to these results, it can be concluded that straetlingite-based sorbents can be used for NH₄⁺ ion removal from a synthetic aqueous solution, as well as for both NH₄⁺ and P removal from industrial wastewater. In the wastewater, a significantly higher sorption capacity of the investigated sorbents was detected for P than for NH₄⁺.     

The effect of gamma-ray irradiation on the sorptive properties of hydrous SiO2 and ZrO2

The sorption capacities of hydrous SiO₂ and ZrO₂ for the Zn(ammine) ion have been observed to increase on irradiation with γ-rays, by ca. 4.1 and 3.8%, respectively. The rates of sorption increase differently in the irradiated exchangers, depending upon their characteristic natures; e. g. when the external concentration of the Zn(ammine) solution is 0.2M, the increase in the F value due to irradiation is more striking in the case of SiO₂ than for ZrO₂. On the other hand, at a lower external concentration of the Zn(ammine) solution (0.01M), the increase in the F value, particularly during the first five minutes, is more significant for ZrO₂.     

Sorption properties of nitrogen-containing ion exchangers

Sorption capacity of ion exchangers based on glycidyl derivatives of aromatic compounds and polyamines was studied in relation to pH of solution. The mechanism of sorption of polyvalent metal ions was examined.     

Preparation of sorbents based on chitosan and its sulfoethyl derivative for sorption of perrhenate ions

The ability of cross-linked chitosan to take up perrhenate ions was studied systematically. The degree of sorption from acetate buffer solution at pH in the interval 2.8–3.1 reaches 85% and more. N-Sulfoethylation decreases the sorption ability of chitosan, but expands the pH interval of sorption and shifts the optimum pH value toward higher acidities. The sorption materials exhibit higher sorption rate than standard synthetic ion exchangers do. The data obtained suggest predominant ion-exchange mechanism of sorption of perrhenate ions onto chitosan and its sulfoethyl derivative.     

Strontium binding properties of inorganic adsorbents

A comparison of strontium sorption on synthetic inorganic ion exchangers and zeolites from 0.01M CaCl₂ solution, sea water and an artificial foodstuff fluid has been carried out in batch and column experiments. It was found that some adsorbents among the groups manganese dioxides, mixed titanium-manganese oxides, antimony-based materials and synthetic zeolites had the highest selectivity to strontium (K _d >1000). These adsorbents are interesting for further investigation concerning their use for radiostrontium decontamination of foodstuffs (if nontoxic), as well as for analytical purposes.     

Effect of environmental conditions on 109Cd(II) sorption to MnO2

The sorption of Cd(II) from aqueous solution on MnO₂ was investigated under ambient conditions. Experiments were carried out as a function of contact time, solid content, pH, ionic strength, foreign ions, fulvic acid and temperature. The results indicated that the sorption of Cd(II) was strongly dependent on pH and ionic strength. At low pH, the sorption of Cd(II) was dominated by outer-sphere surface complexation and ion exchange with Na⁺/H⁺ on MnO₂ surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. The Langmuir, Freundlich and Dubinin–Radushkevich models were used to simulate the sorption isotherms at three different temperatures. The thermodynamic data (ΔG ⁰, ΔS ⁰, ΔH ⁰) calculated from the temperature dependent sorption isotherms suggested that the sorption of Cd(II) on MnO₂ was an spontaneous and endothermic process.     

Kinetics of rhenium sorption from weakly basic macroporous and gel anion exchangers Purolite A170 and Purolite A172 from sulfuric acid solutions

Effect of the grain size of anion exchangers, agitation intensity, and temperature on the kinetics of rhenium sorption on weakly basic macroporous and gel anion exchangers Purolite A170 and Purolite A172 from a 1 M H₂SO₄ solution was studied.     

Sorption characteristics of uranium onto composite ion exchangers

The composite ion exchangers were tested for their ability to remove UO₂ ²⁺ from aqueous solutions. Polyacrylonitrile (PAN) composites having natural zeolite, clinoptilolite, and synthetic zeolite, zeolite X, were used as an adsorbents. The influences of pH, U(VI) concentration, temperature and contact time on the sorption behavior of U(VI) were investigated in order to gain a macroscopic understanding of the sorption mechanism. The optimum adsorption conditions were determined for two composites. The sorption behaviors of uranium on both composites from aqueous systems have been studied by batch technique. Parameters on desorption were also investigated to recover the adsorbed uranium.     

Modification of Surface Forces by Metal Ion Adsorption

Abstract

Sorption of ions may lead to variations in interparticle forces and, thus, changes in the stability of colloidal particles. Chemical interactions between metal ions and colloidal particles modify the molecular structure of the surface, the surface charge, and the electrical potential between colloidal particles. These modifications to the surface and to the electrical double layer due to metal ion sorption are reflected in the interaction force between a particle and another surface, which is measured in this study by atomic force microscopy (AFM). Specifically, AFM is used to investigate the sorption of copper ions from aqueous solutions by silica particles. The influence of metal ion concentration and solution ionic strength on surface forces is studied under transient conditions. Results show that as the metal ion concentration is decreased, charge reversal occurs and a longer period of time is required for the system to reach equilibrium. The ionic strength has no significant effect on sorption kinetics. Furthermore, neither metal concentration nor ionic strength exhibits any effect on sorption equilibria, indicating that for the experimental conditions used in this study, the surface sites of the silica particle are fully occupied by copper ions.     

Radiochemical studies of the sorption behavior of strontium and barium

The sorption behavior of strontium and barium on kaolinite, bentonite and chlorite-illite mixed clay was studied by radioanalytical techniques using the batch method.⁹⁰Sr (29.1 y) and¹³³Ba (10.5 y) were used as radiotracers. Characterization of the solid matrices was done by FTIR and XRD spectrometries and specific surface area measurements. Synthetic groundwater was used as the aqueous phase. The variation of the distribution ratioR _d, as a function of metal ion loading was examined. The sorption isotherms were fitted to various isotherm models. The sorption energies were calculated to be in the range of 8–10 kJ/mol suggesting an ion exchange type of sorption mechanism. In detailed experiments, chlorite-illite mixed clay was first presaturated with K⁺, Sr²⁺, Ca²⁺ and Al³⁺ ions, respectively, prior to sorption studies with Ba²⁺ ions. The results of Ca²⁺ pretreated chlorite-illite were very similar to those of natural chlorite-illite, suggesting that the Ba²⁺ ion exchanges primarily with the Ca²⁺ ion on the clay minerals.     

Superparamagnetic Composites Based on Ionic Resin Beads/CaCO3/Magnetite

The preparation of superparamagnetic composites obtained by CaCO₃ mineralization from supersaturate aqueous solutions is presented. The preparation was conducted in the presence of oleic acid stabilized magnetite nanoparticles as a water‐based magnetic fluid and insoluble templates as gel‐like cross‐linked polymeric beads. The presence of the magnetic particles in the composites provides a facile way for external manipulation using a permanent magnet, thus allowing the separation and extraction of magnetically modified materials. Two ion exchangers based on divinylbenzene/ethyl acrylate/acrylonitrile cross‐linked copolymer—a cation ion exchanger (CIE) and an amphoteric ion exchanger (AIE)—were used, as well as different addition orders of magnetite and CaCO₃ crystals growth precursors. The morphology of the composites was investigated by SEM, the polymorphs content by X‐ray diffraction, and the thermal stability by thermogravimetric analysis. Polymer, CaCO₃, and magnetite in the composite particles were shown to be present by energy dispersive X‐ray (EDX), XPS, and TEM. The sorption capacity for Cu^II ions was tested, as compared to samples prepared without magnetite.     

Influence of the matrix on the complexation of metal ions by chelating ion exchangers

Summary Chelating ion exchangers show distribution coefficients that are considerably lower than those expected from complexation equilibria with the corresponding free ligands in solution. Furthermore, dependence of distribution coefficients on the concentration of exchanging ions in solution is observed. Both effects are due to the influence of the surrounding matrix on the anchor groups. The distribution coefficients of Fe³⁺, Ni²⁺, Cu²⁺, Pb²⁺ and UO ₂₊ ² on two cellulose exchangers carrying different anchor groups are investigated as function of the concentration in solution. In case of the anchor group of high flexibility a strong increase of the distribution coefficients with decreasing concentration in solution is measured. This is explained by the fact that the anchor groups located at the surface are less affected by interactions with the matrix, with the result of higher distribution coefficients. The explanation is in agreement with the sorption isotherm.

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Einfluß der Matrix auf die Komplexierung von Metallionen durch chelatbildende Ionenaustauscher

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Dedicated to Prof. Dr. G. Tölg on the occasion of this 60th birthday