Synergistic mechanism of biochar-nano TiO₂ adsorption-photocatalytic oxidation of toluene

Volatile organic compounds (VOCs) have become one of the primary air pollutants, causing severe harm to the environment and human health. This study combines the biochar adsorption with TiO₂ photocatalytic technology to realize the integration of adsorption-photocatalytic degradation of VOCs. The results show that the specific surface area of the biochar-nano TiO₂ cross-linked structure increases by 660.53 m²/g compared with TiO₂, and the particle size of TiO₂ in the cross-linked structure decreases from 11.10 nm to 9.59 nm. There are chemical bonds between biochar and nano TiO₂, including the Ti–C bond and N-Ti-O structure. The removal rate of toluene by the biochar-nano TiO₂ cross-linked structure is higher than the sum of the adsorption removal rate of biochar and the photocatalytic degradation rate of TiO₂, with a synergy coefficient of 10.45. The absorption capacity of light and visible light is enhanced, and the photocatalytic oxidation efficiency is improved. This study with crucial guiding significance for removing VOCs has elucidated the cross-linking and synergistic mechanism between biochar and nano TiO₂.