P. S. Gordienko

Kinetics of the sorption of heavy-metal ions by a sorbent obtained from boric acid production waste

The results of studies of kinetic regularities of sorption of heavy-metals ions (Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Mn2+) by a sorbent based on calcium hydrosilicate (hereinafter referred to as silicate sorbent) produced from manmade waste formed during the processing of the boron-containing mineral raw materials (boron–gypsum) have been presented.

Study of the Composition, Structure, and Sorption Properties of Nanostructured Aluminosilicates

Sorption properties of synthetic nanostructured potassium aluminosilicates with Si/Al ratios from 1 to 5 fabricated in a multicomponent system KOH–Al2(SO4)3·18H2O–SiO2·nH2O–H2O under static sorption conditions at various temperatures and nitrate salt background have been investigated; the activation energy of cesium ions sorption has been evaluated.

Effect of Temperature on the Kinetics of Sorption of Co2+ and Ni2+ Ions by a Sorbent Based on an Inositol Hexaphosphoric Acid Derivative

Data on the effect temperature has on the kinetics of the removal of Co2+ and Ni2+ ions under static conditions by a sorbent based on a derivative of phytic acid fabricated from rice production waste are presented. It is shown that when the temperature is raised from 20 to 60°C, the sorption capacity of the sorbent based on phytic acid increases over the period of sorption and within 180 min reaches values of 1.4 mmol g−1 for Co2+ ions and 1.3 mmol g−1 for Ni2+ ions. It is established that for the investigated range of temperatures, order n of the sorption of Co2+ and Ni2+ ions is <1, which characterizes the reactions accompanied by diffusion processes. It is found that the process of removal of Co2+ and Ni2+ ions is characterized with low activation energy (20.74 kJ mol−1 for Co2+ ions and 14.2 kJ mol−1 for Ni2+ ions). It is also demonstrated that the sorption process in the considered time frame is best described by a kinetic model of a pseudo-second order, as is indicated by respective correlation coefficients.

Influence of synthetic calcium silicates on the strength properties of fine-grained concrete

The effect of additives based on acicular calcium hydrosilicates (xonotlite and tobermorite) and wollastonite, obtained from boric acid production waste in autoclave synthesis at a temperature of 220 °C, on the strength of fine-grained concrete, has been studied in this paper. It was shown that when the calcium hydrosilicates and wollastonite are introduced, an increase in the strength characteristics of concrete is observed. After heat and moisture treatment, the maximum increase in strength is observed with the addition of 4% of mass content of calcium hydrosilicates and 6% of mass content of wollastonite. After 28 days of hardening under normal conditions, the maximum increase in strength of concrete is observed with the addition of 4% of mass content of both types of additives. It was shown that the water absorption of concrete decreases with a maximum when 4% of mass content is added, as in the case of the introduction of calcium hydrosilicates, and wollastonite. With a further increase in the number of additives, the amount of water absorption increases, but these values remain below the values for the control sample without additives.

Composition, structure, and morphology of nanostructured aluminosilicates

The data on synthesizing nanosized potassium aluminosilicates (PAS) with a ratio of Si/Al of 1–5 obtained in the KOH–Al2(SO4)3 · 18H2O–SiO2 · nH2O–H2O multicomponent system have been presented. Their composition, morphology, and IR and NMR spectra have been studied.

Sorption of cesium ions by nanostructured calcium aluminosilicates

Data on the sorption properties of synthetic calcium aluminosilicates (CASes) with Al: Si ratios of 2: 2, 2: 6, and 2: 10, fabricated within the multicomponent system CaCl2–AlCl3–KОН–SiO2–H2O, are presented. Isotherms of the sorption of Cs+ ions from aqueous solutions with Cs+ concentrations of 0.2 to 6.0 mmol L–1 are analyzed. The CAS maximum sorption capacity and the Langmuir constants are determined. Kinetic data are obtained, and the energy of cation-exchange activation upon the sorption of Cs+ ions is determined. The effect of a salt background (1% KCl + 6% NaCl) has on the values of distribution coefficient (Kd) and the degree of Cs+ ion removal is established.

Effect of ultrasonic treatment on the kinetics of the formation of calcium hydrosilicate from boron-containing technogenic wastes

This work presents some results of studying the effect of ultrasonic treatment on the kinetics of the formation of calcium hydrosilicate from boron-containing mineral feedstock processing wastes, namely, borogypsum. Kinetic parameters and rate constants were determined for the synthesis reactions of calcium hydrosilicate from borogypsum under ultrasonic treatment conditions and conventional stirring.

Electrochemical decomposition of chelate complex of ethylenediaminetetraacetic acid with cobalt

The exponential reduction of the concentration of cobalt ions in the solution with time accompanied by the release of aluminum ions is observed during the electrolysis of aqueous solutions containing Co-EDTA using aluminum electrodes. The conditions and physical and chemical mechanism of the process are under discussion.

Influence of arc-discharge time on microstructure of the Ti-TiC composite

The influence of graphite-anode arc-discharge time on the morphology and sizes of titanium-carbide grains formed in the bulk of VT1-0 titanium alloy is considered.

Effect of hydration and air exposure on sorption properties and phase composition of calcium silicate hydrate

The research results on stability of amorphous calcium silicate hydrate samples in air medium with high humidity and some of their sorption characteristics obtained for low concentrations (from 0.34×10−2 to 0.17 mmol L−1) of cobalt ions in an aqueous medium were presented. It was shown that the sorption capacity of calcium silicate hydrate is affected by the phase composition change, caused by interaction with carbon dioxide to form two calcium carbonate polymorphs, calcite and aragonite, and amorphous silica.