Studies on reaction between KHSO4-VOSO4 system at different temperatures

ABSTRACT

The present study deals with some industrially important vanadium compounds produced as a result of solid-solid interactions between potassium hydrogen sulfate and vanadyl sulfate at different temperatures. The reaction products have been characterized by chemical and thermal analysis, X-ray diffraction patterns, electronic absorption spectra and electrical conductivity. The results of XRD revealed that the reaction products are composed of a mixture of vanadium compounds which possess different valences of tn [KV[SO 4] 2], tetra [K 2VO[SO 4] 2] and pentavalent vanadium [K 3VO 2 [SO 4] 2, K 4[VO 2] 2[SO 4] 2[S 2O 7], KVO 2SO 4, K 2V 2S 2O 12], in addition to some potassium bronze and polyvanadate [KV 6O 15, K 2V 8O 21]. The reactions that lead to the formation of these compounds were suggested and discussed. The identity of these products depends essentially on the temperature as will as the molar ratios of the reactants. The optimum conditions for the formation of soluble vanadium compounds are molar ratio 11 of KHSO 4 and VOSO 4 at 450°C. Under these conditions, up to 78% of vanadium was leached with 0.5 M H 2SO 4 The electrical conductivity was measured over a temperature range of 298 to 590 K at frequency 1y00kHz/s. The reaction products exhibited semiconductor character. The electrical conductivity is proportional to reaction temperature and vanadium ions content. The temperature dependence of electrical conductivity has been discussed on the basis of electronic and ionic conduction mechanism