Fabrication and characterization of In2O3-biochar composites for highly efficient adsorption and photodegradation of dyes

In this study, the In2O3-carbonization wood (In2O3-CW) composites were prepared using waste poplar wood through a comprehensive process involving “delignification-bleaching-impregnation-carbonization”. The morphology, crystal structure, elemental chemical state and photocatalytic activity of In2O3-CW were investigated by SEM, HRTEM, BET, XRD, XPS, UV–vis DRS, PL, EIS, ESR, TOC and LC-MS. Malachite green (MG) served as a model organic pollutant to assess the adsorption and visible-light photocatalytic performance of In2O3-CW in dye degradation. The results indicated a significant enhancement in the adsorption-photocatalytic performance of In2O3 nanoparticles loaded with biomass, leading to a significant increase in the MG degradation rate from 24 % to 76 %. Specifically, when the concentration of MG was 100 mg·L−1, 20 mg of 0.5In2O3-CW removed more than 96 % of MG to 481 mg·g−1. The negatively charged surface of In2O3-CW was observed to be effective in adsorbing MG molecules. Moreover, In2O3-CW exhibited a narrow band gap, high photocatalytic activity, and excellent light harvesting ability, facilitating enhanced photogenerated electron-hole separation and the generation of potent active substances (OH and O2−). Given this knowledge, a detailed deduction of the dye discoloration mechanism was presented, offering a novel approach for the effective treatment of dye wastewater pollution and the realization of high-value applications for waste biomass resources from agriculture and forestry.