Citric acid leaching process for removal of iron (Fe) from rice husk

Abstract

Rice husk containing the highest amount composition of silica (SiO2) compared with other agricultural waste. With such a large availability of rice husk, it becomes economical to industrial by the implementation concept of sustainability beside decompose the rice rusk into ash. The extraction of silica and elimination of metallic element, such as iron (Fe) from rice husk (RH) was treated by leaching process. With this, the RH can be utilized to produce various types of useful renewable resources such as silica (SiO2). Using the organic acid as leaching solution is more eco-friendly instead using the inorganic acid that classified as very dangerous chemical due to the high level of hazard. The treated and untreated rice husk ash characterizes using scanning electron microscopy and X-ray diffraction spectroscopy. The morphology of treated rice husk shows the tubular aggregate due to the presence of alkaline earth metal such as Ca and Mg. Under the optimum condition with 90 °C solution temperature, 60 minutes stirring time, 3% of citric acid and calcination temperature of 800 °C for 3 hours, amorphous silica with more than 78% was prepared via citric acid leaching treatment and combustion process.