Crystallisation of Barium Chromate

Abstract

In the present work the crystallisation of low solubility materials were studied, Barium chromate being chosen as a typical one. The increase in solubility in acid solution was examined. Also the solubility of Barium chromate in the Presence of other compounds (Urea, complexing agents) was Studied. Conditions of supersaturation were created by hydrolising Urea and thus neutralising the acid homogeneously. Hydrolysis The kinetics of Urea were examined and it was found that for conditions of excess Urea the model suggested in the literature was not strictly applicable. An alternative model was suggested by which the hydrolysis of Urea, for pH greater than 2.5,was zero.order. The crystallisation of Barium chromate was studied using a stirred vessel under a variety of conditions (baffies , initial concentration of materials etc.) It was found that the crystals grew to about 20 um (equivalent Spherical radius). It was found that the process obeys an empirical equation of the form: ...