Precipitation and ageing of antimony (III) sulphide

Abstract

Antimony (III) sulphide has been prepared by precipitation from aqueous solution, under different conditions of concentration, temperature, pH and ageing time. The phase composition, crystallinity and particle size of the precipitates have been studied by X-ray diffraction, electron microscopy and vacuum microbalance technique, and correlated with conditions of precipitation. The sulphide samples were prepared from 1 M, 0.5 M and 0.1 M antimony (III) chloride solutions through which hydrogen sulphide gas was passed at 20 °C and 85 °C. The precipitates were aged for different lengths of time, and examined by X-ray powder diffraction and electron microscopy. The surface area and porosity of selected samples were determined by the BET method from nitrogen adsorption isotherms recorded gravimetrically at −196 °C on a vacuum microbalance. However the above sulphide samples, precipitated at relatively low pH, contained impurities pure antimony sulphide was achieved best by precipitation from a dilute solution (0.015 M) of potassium antimonyl tartrate (tartar emetic) with hydrogen sulphide gas. Precipitation occurred then at the relatively higher pH of 4 – 5 in the presence of smaller concentrations of electrolytes, so that the product was very finely-divided and porous.