Depolymerization of polysilicic acid by tiron

As a preliminary experiment for the development of an effective silica scale inhibitor at geothermal power plants, the effect of tiron, a ligand to monosilicic acid, on the polymerization of silicic acid was investigated by gel chromatographic method. The experiments were carried out at Si concentration of 400 ppm (14 mM) and at pH 8 where are a similar condition to geothermal water. The tiron concentration was varied (0-50 mM). At 30 mM of tiron, the polymerization of silicic acid occurred rapidly within first 1 h in spite of the presence of tiron, however, polysilicic acids were depolymerized by tiron. The depolymerization mechanism of polysilicic acids was discussed based on zeta potentials for silica gel particles in the absence and presence of tiron. (C) 2009 Elsevier Ltd. All rights reserved.