High purity and amorphous silica (SiO2) prepared from oil palm frond (OPF) through sol–gel method

Abstract

Malaysia is known as the second largest oil palm producer in the world which subsequently also producing abundant of oil palm biomass either from milling site or plantation site. Oil palm frond (OPF) is one such oil palm biomass that usually produced abundantly in oil palm plantation site and thus it has potential for research of its application and used. This study aims to establish the utilization of OPF in silica synthesis through sol–gel method and its possibility in producing high purity and amorphous silica. To achieve this, OPF processed via several stages of combustion, acid leaching treatment with citric acid and finally silica synthesis via modified sol–gel method. The results obtained shown that from per kg of OPF, ∼3.5% or about 34.7 g of ash was produced that later subjected to acid leaching treatment and managed to recover approximately 18.7 g of acid leached oil palm frond ash (OPFA) or ∼53.9%. From this amount, 68.4% of silica or about 12.8 g of silica successfully produced from the acid leached OPFA. The synthesized silica then characterized using FTIR and presented almost identical spectra with commercial silica specifically at peak at peak 3350–3390 cm−1, 1600–1640 cm−1 and 1040–1100 cm−1 which represent Si-OH bond and Si-O-Si asymmetric bond respectively. The lack of peak at 622 cm−1 indicate that the silica is amorphous in nature and with the acid leaching treatment performed prior sol–gel, possible high purity silica was successfully produced.