Characterization of Silica Extracted from Malang Beach Sand Via Leaching and Sol-Gel Methods

Abstract

Many silica minerals are found in beach sand. One of its beaches is in Bajul Mati beach sand which contains high silica. The silica can be extracted using existing methods, but it is less environmentally friendly. In this research, the extracting process of silica from the sand of Bajul Mati beach (south of Java-Indonesia) has been carried out through a method that is low cost and more environmentally friendly. The study aims to characterize extracted silica with instrumentation results, and economic analysis. The method of extracting silica from beach sand via leaching and sol-gel methods: (1) leaching with 7 M HCl (2) the formation of clear sodium silicate solution (Na2O.xSiO2); (3) sol-gel: sodium silicate solution titrated with oxalic acid (H2C2O4) 1 M until pH 6 was obtained and silicite Si(OH)4 was formed; and 4) characterization with XRF, XRD, FTIR, and SEM with economic analysis. The result showed that extracted silica has a cristobalite structure based on XRD analysis. The purity of silica (% Wt Si) reached 93.9% based on XRF analysis. FTIR analysis has identified silanol, siloxic, and siloxane groups. The SEM analysis shows that SiO2 particles tend to form agglomerations at about ∼1 μm. In addition, economic analysis results showed that this method would support implementation in the future, so silica has been produced by this advanced method.