Citric acid leaching process for silica extracted from oil palm ash for zeolite synthesis

Abstract

Agricultural wastes such as oil palm ash have a possibility to be utilized as a useful renewable source for production of energy and silica (SiO2). Extensive researches have been carried out to extract silica from agricultural wastes, due to silica as a useful raw material for industrial application. Oil palm ash is one of the waste material from the palm oil industry where is was obtained from the burning process of solid waste such as empty fruit bunch, shell and fiber. Oil palm ash contains a large amount of silica. This study has been conducted to extract silica from palm ash by removing impurities using citric acid via leaching process. Various experimental parameters, such as acid concentration (1 to 6 %), reaction time (30 to 180 minutes), leaching temperature (30 to 90 C) and solid/liquid ratio (1:50 – 1:10) were investigated. Then, the effect of each parameter towards extraction process was evaluated using XRF, FTIR, XRD and SEM. The optimum extracting condition was achieved at 3% concentration of citric acid, 70C of solution temperature, 60 minutes of reaction time and 1:25 ratio of solid/liquid. XRF results show that the content of silica in treated palm ash can reach up to 92% after citric acid leaching treatment. The transmittance peaks at 798 - 778 cm-1 show that silica element is absent in the treated palm ash. Preliminary tests have shown that there is a possibility of using silica extracted from palm ash to synthesize zeolite.