Oleg D. Linnikov

Investigation of the initial period of sulphate scale formation Part 1. Kinetics and mechanism of calcium sulphate surface nucleation at its crystallization on a heat-exchange surface

Crystallization of calcium sulphate on electrolytic solutions on a heated metal surface was studied in the laboratory. Using a microscopic method, studies concentrated on the initial period of sulphate scale formation (up to the formation of a compact monolith layer of calcium sulphate on a metal surface). The kinetics and mechanism of nucleation of calcium sulphate crystals were investigated. The activation energy of nucleation and efficient specific surface energy were determined. The effect of a temperature gradient in a solution at the metal surface and its roughness on nucleation of calcium sulphate crystals was estimated.

Removal of Cr(VI) from aqueous solutions by magnetite nanoparticles with different sizes and crystal structure

AbstractIn this work a few nanopowders of magnetite (Fe3O4) produced by different methods were used as a sorbents. Three techniques were applied to make the nanopowders: (1) gas-phase synthesis, (2) chemical precipitation from water solution, and (3) laser atomization. Using these methods, the particles with different sizes and crystal structure have been produced. The effects of the particles size and structure of nanopowders on the removal of toxic Cr(VI) from an aqueous solution imitating ground waters and wastewaters with pH = 7.4–7.8 were studied at different solution temperatures. It is shown that magnetite is effective sorbent for the removal of Cr(VI) from polluted natural waters and sewage. It is found that sorption of Cr(VI) by magnetite is irreversible and has chemisorption character, and even small rise in temperature of the solution during the sorption process sharply increases efficiency of the sorption.

About seed concentration for prevention of scale

The question of the most efficient seed concentration for prevention of scale was considered theoretically. Seed crystals decrease supersaturation of scale-forming salts in a solution. Thus the growth rate of scale also decreases. Equations describing these processes were derived. Good agreement was found for the theoretical equations with data published in the literature.

Investigation on purification of hydrochloric acid by membrane method

Abstract A process of hydrochloric acid transfer through an anion exchange membrane at its regeneration from acid wastewaters has been studied. An equation describing the diffusion process of components in the examined membrane system has been derived and experimentally tested. General mass transfer coefficients of hydrochloric acid and molecules of NaCl, CdCl 2 , NiCl 2 , and ZnCl 2 through the anion exchange membrane have been determined.

Prevention of scaling and corrosion by reagent KISK-1

AbstractThe influence of the reagent KISK-1 (Russia) on the rate of corrosion of Steel 3 in mineralized (“hard”) waters of two industrial plants was studied. The water supply system of the two plants used in the study had sufficient difference in chemical composition. Thermostability of these waters was investigated in the presence of KISK-1 (the complex inhibitor of scaling and corrosion). It was shown that when used at correct dosage, KISK-1 is capable of significantly reducing the rate of corrosion of Steel 3 while also providing the water system’s thermostability in evaporation, i.e. preventing the formation of sediments and deposits of salts. It was shown that the optimum dosage of KISK-1 remains relatively stable, while the tested waters were evaporated by 1.7–2.5 times. At the same time, the existence of some threshold concentration, above which the increase in the concentration of KISK-1 does not produce a proportional decrease in the rate of corrosion of Steel 3 was established. The approach offe...

Application Of Fe3O4 Nanoparticles For Metallic Cations Removal From Water Solution

Sedimentation of nanopowders of magnetite Fe3O4 in water solution was studied by optical method. Larger particles (50 nm) are sedimenting effectively during several minute, while for particles close to 20 nm more than 24 hours is required for full sedimentation in a solution of 5 g/l. Although the magnetization of nanopowders is noticeably less than that in a bulk material it provides a significant contribution to attractive interactions between particles, thus promoting the heavy aggregates formation. It has been shown that sedimentation rate can be strongly increased under the action of a gradient magnetic field dH/dz = 1.7 kOe/cm.