Preparation of a Novel Straw–Sludge Activated Biochar and Its Adsorption Mechanisms for Removal of VOCs

To simultaneously achieve the objectives of waste resource utilization and clean production, a novel approach involving the utilization of corn straw-sludge hybrid biochar was proposed for the adsorption of VOCs emitted from biomass power plants. This study analyzed the effect of straw-sludge biochar on the adsorption characteristics of VOCs (toluene, isopentane, and ethylene) under different preparation conditions (raw material ratio, activation temperature, and activation time). The findings revealed that the adsorption efficiency of the mixed biochar was significantly superior to that of individual corn straw biochar and sludge biochar. The adsorption of methylbenzene, isopentane, and ethylene was 78.32, 40.81, and 41.18% higher, respectively, compared to the control groups consisting of pure sludge biochar and pure corn straw biochar. Moreover, the adsorption performance of the activated biochar followed the sequence of ethylene < isopentane < methylbenzene in terms of both saturation time and adsorption capacity. The adsorption capacity of VOCs on straw biochar-sludge biochar demonstrated a consistent correlation with the boiling point and molecular weight of the adsorbate, with higher adsorption capacities observed for adsorbates with larger boiling points and molecular weights, specifically methylbenzene > isopentane > ethylene.