Rice husk char as a sustainable material for the preparation of graphene oxide-supported biocarbons with mesoporous structure: A characterization and adsorption study

Rice husk (RH) is a biomass-based waste that can be used to produce sustainable energy. RH carbon (RHC) and RH ash (RHA) remain in solid char after the transformation of RH into heat energy. To effectively use RHC and RHA wastes, this study proposed using two graphene oxide (GO)-based carbonaceous composites: RHC/GO and ordered mesoporous carbon (OMC)/GO. RHC was prepared through the high-temperature pyrolysis of RH. OMC was obtained by recycling RHA as a silica template source. The experimental results demonstrated that surface areas and pore volumes of carbonaceous composites were increased after the addition of GO. Both RHC/GO and OMC/GO materials exhibited a mesoporous structure with a surface area of 618 and 1068 m2/g, respectively, and a pore volume of 0.533 and 1.143 cm3/g, respectively. Rhodamine B (RhB) was used to evaluate the effects of solution pH, adsorbent dosage, and the initial concentration of the relevant dye on the adsorption capacities of the two carbonaceous composites. OMC/GO had a relatively satisfactory performance for the elimination of RhB compared with RHC/GO. The findings of kinetics and isothermal adsorption studies for RHC/GO and OMC/GO implied that adsorption obeyed the pseudo-second-order and Langmuir models. RHC and RHA can be beneficial for synthesizing nanoproducts and reducing biowastes.