Determination of conversion reaction mechanism of celestite to acidic strontium oxalate hydrate in aqueous solution of H2C2O4

The conversion of celestite to acidic strontium oxalate in H2C2O4 solutions proceeds in two consecutive reaction steps. In the first step, SrC2O4·H2O is formed and in the second, H[Sr(C2O4)1.5(H2O)] is formed. The conversion reaction ends by the formation of SrC2O4·H2O on the surfaces of the celestite particles. The saturation concentration of H[Sr(C2O4)1.5(H2O)] chelate compound decreases during cooling of the solution and the excess amount of Sr(HC2O4)(C2O4)0.5·H2O crystallizes. XRD, ICP - OES and simultaneous TG/DTA - MS analytical techniques were used to explain the conversion reaction mechanism.