Optimization of silica (SiO2) synthesis from acid leached oil palm frond ash (OPFA) through sol-gel method

Abstract

Silica (SiO2) synthesized from agricultural waste has been investigated in various studies recent years where majority of this research utilized Stöber method or also widely known as sol-gel method to extracting silica from this source. This study aims to propose an optimized condition for silica synthesis via sol-gel method synthesis performed on the acid leached oil palm frond ash (OPFA). Two parameters in sol-gel method which is the NaOH molarity and acid leached OPFA concentration were investigated. Different concentration of NaOH molarity at 1 M, 2 M and 3 M were analyzed then followed with analysis on different OPFA concentration at 0.03 g/ml, 0.06 g/ml and 0.1 g/ml that may affect the yield of silica synthesized from acid leached OPFA. From the research it shown that acid leached synthesis at 2 M of NaOH and at 0.06 g/ml acid leached OPFA produced a significantly higher yield of silica approximately at ∼68%. The synthesized silica at this optimized condition were characterized by using FTIR analysis and comparing it with commercial silica. The spectra resulted from the commercial silica as well as silica synthesis from the acid leached OPFA at optimized condition depicting almost similar spectra with 3 identical peaks at ∼3420–3428 cm−1, ∼1600 cm−1 and ∼1040–1100 cm−1. This FTIR result attest that both commercial silica and the synthesized silica contain almost similar chemical composition. This also proven that OPF can be a viable source of silica as it is an abundant biomass produce in oil palm plantation and can provide a sustainable and economic alternative to the conventional silica production.