Surface modification of carbonised waste rice husks by mild hydrothermal treatment

Abstract

Carbonisation process is a way in exploiting rice husk to produce alternative carbon material. In this study, rice husk was carbonised at 500°C, 2 h in inert environment. Mild hydrothermal treatment of carbonised rice husk was conducted by using potassium hydroxide (KOH) and potassium persulfate (KPS) as reactants in different parameters: 1) the reactants molar ratio; 2) reaction time. The treated carbonised rice husks were tested for its dispersion, morphology observation, elements and functional groups determination. From the results, the modified carbonised rice husks showed improvement in its dispersion with polar solvent while no defects in the structures were observed from the SEM images. High oxygen content was found in EDX analysis for modified carbonised rice husks treated in KOH: KPS with molar ratio of 3:1. The presence of hydroxyl and carboxyl groups from the FTIR spectra shows that the treatment successfully introduced functional group to the carbonised rice husk surface.