Optimizing Silica Extraction form Rice Ash: A Comparative Study of Alkaline and Acid Leaching

Abstract

This research aimed to study the characteristics of silica which had been extracted from rice ash using two methods, i.e. alkaline and acid leaching. There were five types of solutions used; 1M and 2M sodium hydroxide (NaOH) solutions, 1M and 2M potassium hydroxide (KOH) solutions, and a 1M hydrochloric acid (HCl) solution. After the extraction process, the amount of silica was calculated and analyzed using FTIR and XRD. Based on FTIR analysis, the Si-O-Si group was found within the frequencies range of 782 cm−1 to 798 cm−1 while the Si-O group was found within the 3671 cm−1 to 3751 cm−1 range and the O-H group was found at 86.4541 cm−1. XRD showed crystallinity index results of 44.0%, 46.4%, 13.0% and 45.1% from the variations of KOH, (1M and 2M) and variations of NaOH (1M and 2M) respectively. The usage of 1M of HCL contributed to the optimum production of silica up to 8.1g with the percentage yield of silica was 40.5%.