The crystallization of magnesium hydroxide

The thermodynamic association constant for the formation of the ion-pair MgOH+ in solutions of magnesium hydroxide has been studied by potentiometric and conductometric methods. The growth of magnesium hydroxide seed crystals in supersaturated solutions over a range of concentrations of magnesium and hydroxide ions and in the presence of phosphonate additives has been investigated by a precision conductance method. After a rapid initial surge of growth, an equation first order with respect to supersaturation can be used to explain the experimental data. A surface diffusion process is proposed as the controlling step in the crystallization process.