Thermal analysis of activated carbons modified with silver metavanadate

Abstract

The effect of silver metavanadate doping on physicochemical properties and thermal behaviour of the activated carbons obtained from waste materials was investigated. The carbonaceous supports were subjected to carbonisation at 400 or 600°C. The samples carbonised at 600°C have much more developed surface area and porous structure than the analogous samples obtained at 400°C. Impregnation of activated carbons with silver metavanadate leads to a decrease in their surface area and pore volume. According to thermal analysis (TG, DTG) in the samples containing 1 and 3wt.% of silver metavanadate, AgVO3 is fully decomposed to do vanadium oxide and Ag, with no intermediate products, while in the samples containing 5wt.% AgVO3, this salt is decomposed to vanadyl species as intermediate compounds at 350°C before the formation of V2O5 at 500°C. Moreover, in all samples impregnated with silver metavanadate the nanoparticles of silver undergo crystallisation leading to reduction of Ag+ ions from the vanadium salt to Ag0.