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The adsorption properties of Ukrainian Transcarpathian clinoptilolite in aqueous copper(H) solutions under dynamic conditions have been investigated. Under optimum conditions (pH of Cu2+ solution = 7.1; adsorbent thermally modified at 120-170°C for 2.5 h; flow rate of Cu2+ solution through adsorbent = 3 ml/min), the adsorption capacity of the clinoptilolite towards copper amounted to 725 ng/g. The conditions for the desorption of copper(II) from clinoptilolite have been studied. Of the desorbents tested, the best were HNO3 (1:1) and HNO3 (1:2) solutions. Their effectiveness in extracting copper(II) ions under the desorption conditions employed amounted to 100%.

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The adsorption properties of Ukrainian Transcarpathian mordenite in aqueous copper(II) solutions under dynamic conditions have been investigated. Under optimum conditions (pH of Cu2+ solution = 6.5; adsorbent thermallly modified over 2.5 h at 150°C; rate of passage of Cu2+ solution through adsorbent = 3 ml/min) the adsorption capacity of the mordenite towards copper amounted to 1020 μg/g. Copper is effectively desorbed by an aqueous solution of HNO3 (1:2). Under optimum desorption conditions the effective extraction of copper was 99.8%.

BackgroundIn spite of the fact that terbium is one of the rarest elements in the Earth’s crust, it is frequently used for the production of high technological materials. At the result, an effective combination of sample preparation procedure and detection method for terbium ions in different matrices is highly required. The solid-phase extraction procedure with natural Transcarpathian clinoptilolite thermally activated at 350 °C was used to preconcentrate trace amounts of terbium ions in aqueous solutions for a final spectrophotometric determination with arsenazo III.ResultsThermogravimetric investigations confirmed the existence of relations between changes that appeared during dehydratation of calcined zeolite and its sorption affinity. Since the maximum of sorption capacity towards terbium was observed at pH 8.25, a borate buffer medium (2.5 · 10−4 М) was used to maintain ionic force and solution acidity. Terbium was quantitatively removed from the solid-phase extraction column with a 1.0 M solution of sodium chloride (pH 2.5). The linearity of the proposed method was evaluated in the range of 2.5-200 ng · mL−1 with detection limit 0.75 ng · mL−1.ConclusionsDue to acceptable recoveries (93.3–102.0 %) and RSD values (6–7.1) from spiked tap water, the developed method can be successfully applied for the determination of trace amounts of terbium ions in the presence of major components of water.Graphical abstractSorption of terbium(III) ions on clinoptilolite

The sorption properties of Transcarpathian clinoptilolite towards Nd(III) and Gd(III) under dynamic condition have been studied. Nd(III) was sorbed with the best efficiency on the uncalcined clinoptilolite samples from the solutions at pH 6.5. Clinoptilolite samples that were previously calcined at 250 • C exhibit the maximal sorption capacity towards Gd(III) from the solutions at pH 9.5. Nd(III) and Gd(III) sorption on clinoptilolite mechanisms are different: Nd(III) is sorbed according to the ion-exchange mechanism, and the sorption of Gd(III) is carried out mainly by means of the adsorption of soluble hydrolyzed forms of Gd(III) on the zeolite surface. The differences in sorption mechanisms of these lanthanides give an opportunity to separate Nd(III) and Gd(III) from the solutions at pH 9.5. The maximal sorption capacity of the clinoptilolite regarding Nd(III) and Gd(III) at the optimal conditions was found to be 1810 and 6500 µg/g. The best desorbent of Nd from the clinoptilolite is 7 M HNO3 solution. The best desorbent of Gd is 1 M solution of KCl acidified to pH 2.6, which provides a 100% withdrawal of Gd from the zeolite matrix. Transcarpathian clinoptilolite is proposed as a sorbent for the preconcentration of trace amounts of Nd(III) and Gd(III) from aqueous solutions in a solid phase extraction mode.

The results of testing of Pd(II)-Cu(II)/Bent catalyst samples in the reaction of CO oxidation with air oxygen are presented. Bentonites from three Ukrainian deposits: Gorbskoye, Dashukovskoye, and Kirovogradskoye were used as supports. Natural bentonites, their modified forms, and the catalysts based on them were characterized by X-ray diffraction phase analysis, FT-IR spectroscopy, and chemical analysis. It has been found that the activity of Pd(II) Cu(II)/Bent catalysts increases with increasing amorphous silica content and with decreasing pH of their water suspensions.

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