A sustainable route for production of graphene oxide-contained nanostructured carbons from rice husk waste and its application in wastewater treatment

Abstract

Agricultural biomass, such as rice husk (RH), is a renewable source of bioenergy. However, a large amount of RH ash (RHA) is generated after the thermal conversion of RH. The main component of RHA is silica (>85 wt%). This study used recyclable RHA as a mesoporous SBA-15 template source. Next, ordered mesoporous carbon/ graphene oxide (RH-CMK-3/GO) composites were synthesized through the direct carbonization of GO, sucrose, and an SBA-15 template. Experimental data demonstrated that GO was successfully conjugated on the surface of CMK-3. The RH-CMK-3/GO exhibited a highly ordered mesostructure, which was not affected by the incorporation of GO. Compared with bare RH-CMK-3, the RH-CMK-3/GO had an enhanced surface area and pore volume. The composite exhibited a highest pore volume of 1.143 cm 3/g, a surface area of 1138 m2/g, and a pore diameter of 3.68 nm. The RH-CMK-3/GO revealed a higher ability for the adsorption of rhodamine B (RhB) than did the SBA-15, SBA-15/GO, and pure CMK-3 materials. The removal of RhB increased with increases in the composite dosage, solution pH and temperature, and carbonization temperature and time and a decrease in the initial RhB concentration. Moreover, the RH-CMK-3/GO exhibited a highest removal efficiency of 100%. The thermodynamics, kinetics, and isotherm adsorption data for the RH-CMK-3/GO composite exhibited satisfactory fitting for the endothermic, pseudo-second-order, and Langmuir models, respectively. Moreover, the composite exhibited good reusability. These results suggest that RHA can be effective for the fabrication of valuable mesoporous carbon nanocomposites and the elimination of organic contaminants from wastewater.