Synthesis and characterization of silica gel from Lapindo mud Sidoarjo

Silica gel was synthesized from Lapindo mud by the sol-gel process. XRF analysis confirmed that Lapindo mud contained silica (50%) which was major components, therefore Lapindo mud has great potential as a raw material for silica gel synthesis. Metal silicates commonly used as a precursor to prepare silica gel. A Lapindo mud was mixed with an alkaline solution, stirred and heated to prepare metal silicates. Hydrochloric acid was then slowly added to the metal silicates solution to obtain silica gel. The pH 4 selected as the optimum pH in the synthesis of silica gel. The purity of synthesized silica was determined by XRF and shown that silica purity by 100 mL sodium hydroxide 6 M (4 h, 80 °C) treatment was 63.25% with optimum yielded 32.3%. Whereas 12 M potassium hydroxide 200 mL (5 h, 90 °C) treatment could be produced better purity up to 77.71% with a yield of 39.72%.