JOURNAL of the Tunisian Chemical Society

Silica contained in brackish and geothermal waters may cause precipitation and/or fouling problems. Prediction and prevention of these phenomenas need the study of the effect of different parameters on silica solubility. The analytical methods used for determining silica are gravimetry, two absorptiometric determinations using either the yellow rnolybdic acid or the molybdenum blue complex and atomic absorption spectrophotometry. The effect of temperature and pH on amorphous silica solubility are studied. Solubilities are mesured in the following aqueous salts solutions at various concentrations: NaCl, KCl, MgSO₄ , CaCl₂ MgCl₂, LiCl, NaNO₃, KNO₃ and LiNO₃. The experimental values lead to empirical equations for the effect of the studied parameters on amorphous silica solubility. These experimental solubilities allow to deduce the activity coefficients of silica in salt solutions. The results are discussed and compared with those available in literature.

B. Hamrouni, F. El Mannai, M. Dachraoui

amorphous silica, determination, solubility, pH, temperature and salt effect

Pages 1135-1145