The nucleation and precipitation of nickel ammonium sulphate crystals from aqueous solution

Abstract

Abstract A precipitation study has been made with nickel ammonium sulphate produced by mixing aqueous solutions of its constituent salts. Rates of nucleation, as indicated by the induction period, were measured for both agitated and non‐agitated systems over the temperature range 0–35 °C. The nucleation rate increases with increases in agitation and temperature but supersaturation has the dominant effect, as predicted by classical nucleation theory. However, attempts to analyse the results in accordance with classical theory were not entirely successful, but it is shown how the assumption of (a) a variation of crystal surface energy with temperature and (b) the influence of heterogeneous nucleation can account for the discrepancies.