Effect of pH, Concentration and Temperature on Copper and Zinc Hydroxide Formation/Precipitation in Solution

Understanding the effect of temperature on the speciation of multivalent metals in solution is essential for many applications in industry. The results of the present Cu(II) and Zn(II) solutions speciation studies in tandem with thermodynamic calculations have shown that Cu or Zn ions proliferate in acidic solutions whilst in alkaline medium, solid Cu(OH)2 or Zn(OH)2 colloidal particles form. The extent of metal hydroxide precipitation accentuates with increasing Cu(II) and Zn(II) concentrations or temperature in the manner predicted by thermodynamic modelling. More solid Cu(OH)2 and Zn(OH)2 is formed and precipitates with increased temperature. The influence of temperature and concentration on the hydrolysis of Cu(II) and Zn(II) species, specific adsorption of the hydrolysis products and surface nucleation onto silica particles are shown to have a striking impact on the zeta potential at high pH.