Recovery and characterization of naturally occurring silicon dioxide from corn wastes

Abstract

Corn husks, cobs, and stalks are Indonesian agricultural waste products which are present in abundance. The reusability of these wastes is still limited to traditional applications, such as the base for animal feed, organic fertilizer, or handicrafts. On the other hand, corn - which is belong to the Family Poaceae - is a rich and economic source of naturally occurring silicon dioxide minerals, with size ranging from micrometer to nanometer. Silicon dioxide and its reduced product silicon, recovered from corn waste possess potential application in various fields, ranging from semiconductor, pharmaceutical, catalysis, gas adsorption, to lithium-ion batteries technology. The application depends on its physical, chemical, and electrochemical characteristics. In this work, corn husks, cobs, and stalks are processed through leaching at various HCl concentration, followed by atmospheric decomposition at moderate temperature to obtain silicon dioxide for further suitable application. Morphological characteristic is analyzed by SEM images, crystallinity of silica is investigated by XRD, while possible organic contaminants are detected by FTIR. The result shows that corn husks provide the highest silicon dioxide yield at 2.543 wt.% compared to cobs and stalks obtained from the same condition, which are 0.457 wt.% and 2.030 wt.%, respectively. Powders obtained from corn husks also indicate a higher purity with insignificant metallic or organometallic contaminants, showing closest crystal structure to the mixture of quartz and amorphous silicon dioxide.