Dissolution of quartz sand in sodium hydroxide solution for producing amorphous precipitated silica

This research studied the dissolution of quartz sand in sodium hydroxide solution as an effort to form silica precipitate. The dissolution process was carried out using the leaching method directly at atmospheric pressure. The process variables in this study included the concentration of sodium hydroxide solution, temperature, dissolution time, and stirring rate. The four process variables had a positive influence to enhance silica precipitate formation, The result showed that the extraction rate was still low even though the SiO2 concentration in the starting material was very high. Temperature provided the most significant influence among other process variables. The result exhibited that silica precipitate content was 13.6% obtained in the optimum condition at a temperature of 90 °C with a stirring speed of 800 rpm using a 7.5 M of sodium hydroxide solution.