Study on Plasma-Stimulated Remediation of Radioactively Contaminated Soil

Abstract

The article is devoted to the problem of rehabilitation of soils and waste waters contaminated with Cs¹³⁴, Cs¹³⁷and Sr⁹⁰ radionuclides. To extract radionuclides from aqueous solutions, we used the method of precipitation of cesium and strontium by selective sorbents of transition metal ferrocyanides with their plasma activation. Sorbents of this type are obtained by precipitation of ferrocyanides of the corresponding metal in the presence of finely dispersed calcium and strontium carbides synthesized in the plasma treatment zone. Such finely dispersed sorbents have an increased selectivity and extraction rate (more than 100 times). This is a consequence of the fact that the coprecipitation of micro amounts of cesium and strontium coincides with the synthesis and activation of the sorbent in the chemically active zone of the plasma discharge.  In addition, the concomitant oxidation of organic substances eliminates their negative effect on sorbents. A pilot plant was developed and tested using a nonequilibrium electric discharge in a flowing aqueous solution with plasma-chemical synthesis of a sorbent to reduce the amount or remove radioactive materials from soils and wastewater contaminated as a result of the accident at the Fukushima Daiichi nuclear power plant. It is shown that this method of plasma-chemical synthesis and activation of the sorbent makes it possible to effectively purify wastewater with different composition and concentration of radionuclides in the presence of surfactants and organic pollutants, as well as soil with a combination of hydroseparation.