Modelling of Nano Silica Formation from Geothermal Silica Using Co-Precipitation Method

Abstract

Nanosilica is a nanotechnology product with many substantial functions in many industries. Previous research showed that nano silica can be synthesized from geothermal silica, that caused silica scaling in injection well and turbine in geothermal power plant, reducing its power plant capacity by 40%. This research used geothermal silica as a precursor for nanosilica production with co-precipitation to recover amorphous silica from silica geothermal to reduce scaling while also increasing its economic value. The objectives of this study were to determine the model to represent the co-precipitation method for nano-silica by using nucleation and growth modelling, therefore help the scale-up process of nanosilica production. The experiment was conducted in four steps. (1) Silica washing utilized distillate water with a ratio of water to silica of 10:1 and sulfuric acid of 20% with a ratio of acid to silica of 4:1, both as a washing agent. (2) Preparation of HCl with concentrations of 3% and 9%. (3) Preparation of sodium silicate solution by reacting washed silica and NaOH to obtain sodium silicate. (4) Preparation of primary and secondary sodium silicate by diluting sodium silicate by two and four times to obtain primary and secondary sodium silicate, respectively. (5) Precipitation of sodium silicate with HCl consists of two steps using primary and secondary sodium silicate. The result showed that the model fit concentration data, with Sum of Squared Error (SSE) 1.9297.10-4, mass transfer coefficient rate is 9.8.10-3 dm/min, and the average relative error is 3.5%.