Effects of operating variables and additive on the induction period of MgSO4–NaOH system

The effects of several operating variables, including initial reagent concentration, temperature, mixing speed and presence of ethylenediaminetetraacetic acid (EDTA), on the induction period of Mg(OH)2 were studied experimentally. The conductivity method was used for the determination of induction period. The results showed that the induction period increases with a decrease in initial reagent concentration, temperature and mixing speed. The presence of EDTA in solution increases the crystal-solution interfacial energy and prolongs the induction period and provides an adequate time for the supersaturation distribution uniformity of aim production. On the other hand, the plot of ln tind against (ln S)−2 is a straight line, which conforms to the classical homogeneous nucleation theory, and the correlation coefficients of the results are all above 0.98.