Desulfurization of Industrial Sulfide Alkaline Solutions by Mixed Sorbents

Abstract

Modern methods of purification of hydrocarbons (oil, gas) from sulfur-containing compounds (H₂S, RSH, RSSR, naphthenic acids, NaHS, Na₂S) have been analyzed, which are based on their alkaline extraction followed by oxidation of air oxygen on homogeneous or heterogeneous catalysts. Despite the promising process of catalytic oxidation of sulfur-containing compounds in technical solutions, it has a number of significant drawbacks, primarily related to the activity of the catalyst and the ability to form a large number of intermediate products of the oxidation. Other known methods for the removal of sulfur-containing compounds from technical solutions are based on the chemical interaction of sulfide alkaline solutions with aqueous solutions of metal salts of III-V analytical groups or their interaction with elemental sulfur to form the corresponding sodium polysulfides. A number of studies have investigated the sorptive extraction of sulfur-containing compounds from technical aqueous solutions or commercial hydrocarbons/diesel fuels using various modifications of activated charcoal, natural sorbents, polymeric organic absorbers or mixed sorbents. However, despite the wide variety of sorptive materials studied, the problem of purification of industrial wastewater from sulfur-containing compounds is not completely solved and, in turn, depends on the chemical structure of the surface of the sorbent, as well as on the objects of purification, pH of media and several other factors.

It has been developed an alternative method of purification of aqueous sulfide alkaline solutions/wastewater from sulfide and hydrosulfide ions by their adsorption on pre-regenerated mixed sorbents consisting of activated charcoal (AC) of brand Decolar A and kieselguhr (K) of brands Becogur 200 and Becogur 3500 with mass ratio of 4 : 6. It has been found that the degree of purification of the investigated solutions, which is strongly dependent on the initial concentrations of sulfide and hydrosulfide ions, is 95,7…96,6 % and indicates the high efficiency and possibility of using such technologies in industrial production.

Surface study of mixed sorbents (AC+K) after purification of aqueous solutions was performed using X-ray phase analysis. The received data confirms the amorphous composition of the activated charcoal and the presence of the main SiO₂ cristobalite, 4,02, on the left side of the diffractogram, as well as a number of peaks of various Na₂S modifications.