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Studies in Surface Science and Catalysis

The study was carried out on the sorption of heavy metals (Ni2+, Cu2+, Pb2+, and Cd2+) under static conditions from single- and multicomponent aqueous solutions by raw and pretreated clinoptilolite. The sorption has an ion-exchange nature and consists of three stages, i.e., the adsorption on the surface of microcrystals, the inversion stage, and the moderate adsorption in the interior of the microcrystal. The finer clinoptilolite fractions sorb higher amounts of the metals due to relative enriching by the zeolite proper and higher cleavage. The slight difference between adsorption capacity of the clinoptilolite toward lead, copper, and cadmium from single- and multicomponent solutions may testify to individual sorption centers of the zeolite for each metal. The decrease of nickel adsorption from multicomponent solutions is probably caused by the propinquity of its sorption forms to the other metals and by competition. The maximum sorption capacity toward Cd2+ is determined as 4.22 mg/g at an initial concentration of 80 mg/L and toward Pb2+, Cu2+, and Ni2+ as 27.7, 25.76, and 13.03 mg/g at 800 mg/L. The sorption results fit well to the Langmuir and the Freundlich models. The second one is better for adsorption modeling at high metal concentrations.

Study of the selection mechanism of heavy metal (Pb2+, Cu2+, Ni2+, and Cd2+) adsorption on clinoptilolite.

Structural and physicochemical properties of natural zeolites: clinoptilolite and mordenite

Ammonium sorption from aqueous solutions by the natural zeolite Transcarpathian clinoptilolite studied under dynamic conditions

Step-wise dealumination of natural clinoptilolite: Structural and physicochemical characterization

Adsorption of cadmium on acid-modified Transcarpathian clinoptilolite

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%.

https://journals.sagepub.com/doi/pdf/10.1177/026361749901700206

Adsorption of copper on transcarpathian clinoptilolite

In 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. Thermogravimetric 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. Due 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.

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A solid-phase extraction method using Transcarpathian clinoptilolite for preconcentration of trace amounts of terbium in water samples

Sorption of terbium on Transcarpathian clinoptilolite

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...

V.O. Vasylechko

Papers

Adsorption of cadmium on acid-modified Transcarpathian clinoptilolite

Adsorption of copper on transcarpathian clinoptilolite

A solid-phase extraction method using Transcarpathian clinoptilolite for preconcentration of trace amounts of terbium in water samples

Sorption of terbium on Transcarpathian clinoptilolite

Adsorption of Copper on Transcarpathian Mordenite