Horda R. Sorption of noble metals on the surface of silica gel and phytosorbents with grafted thiourea groups

Тhe study of colloid-chemical features of ecologically safe and economically acceptable methods of sorbents synthesis based on silica gel, crystalline cellulose and pine (Pinus sylvestris) sawdus chemically modified by thiourea groups; determination of sorption conditions of noble metals from technological solutions on the surface of synthesized sorbents; development of methods determination or technological extracted of these metals on the basis used of the obtained sorption materials. It is proved that all investigated sorbents effectively extracted noble metals from acid solutions under optimal conditions for sorption processes. The time of the obtaining sorption equilibrium on silica gel, chemically modified by thiourea groups is 15 minutes, on the surface of pine sawdust, chemically modified with thiourea groups − 1 hour during heating and 24 hours at room temperature. The influence of heavy metals has been studied and it is shown that their significant quantities do not affect the completeness of the extracted of noble metals. Kinetics sorption and isotherms was analyzed using modern colloid-chemical models. It is shown that the experimental data obtained are best described by the kinetic pseudo-second order model and the Langmuir adsorption model. The noble metals sorption in a dynamic regime on the surface of crystalline cellulose chemically modified by thiourea groups was investigated. However, the fact that the time of establishing the sorption equilibrium is high, restricts the possibility for industrial use of the proposed sorbent for the extraction of metals in a dynamic mode. The method of sorption-colorimetric determination of Pd(II), Rh(III) and Ru(IV) with the use of silica gel chemically modified with thiourea groups was developed. The same technique was developed for Hg(II) using its colored complex with Michlera`s thioketone. For the first time, based on the systematic study of colloid-chemical of sorption conditions, the feasibility and high efficiency of the use of phytosorbents for the extracted of noble metals in powder form, or in highly concentrated desorbates, have been scientifically substantiated and experimentally proved.