2014 Volume 36 Issue 1 Pages 33-40
In order to elucidate whether polyacrylic acid (PAA) accelerates the deposition of silica scale from geothermal water at geothermal power plants, some laboratory experiments were conducted. All experiments were carried out at pH 8-9. The PAA alone or Ca did not affect the polymerization of silicic acid in solution. When silica gel was added into silicic acid solutions containing aluminum ion (Al) and PAA, the PAA forms a Al-PAA complex and the complex adsorbs on the surface of silica gel. The dissolution of silica gel was retarded by adsorption of the Al-PAA complex. The adsorption of monosilicic acid on the surface of silica gel was also accelerated. From the experimental results, it can be reasonably considered that the addition of PAA into geothermal water causes both the retardation of dissolution of silica scales and the acceleration of deposition of monosilicic acid (growth of the silica scales).
