In response to the requirement for efficient control of Volatile Organic Compounds (VOCs) under the "Dual Carbon" goals, ethanol and benzene—two VOCs with different polarities—as target pollutants were selected, and their adsorption on TiO2 were investigated, with a focus on the effects of illumination conditions, initial water content, VOCs concentration, and interactions in binary-component systems on removal efficiency. The results revealed that in dry environments, within single-VOC systems, the removal rate of ethanol was significantly higher than that of benzene. This was attributed to ethanol's higher equilibrium adsorption capacity on TiO2 and the hydroxyl functional group of ethanol, which facilitated interfacial charge transfer with photogenerated holes. When water vapor was introduced into the system, the removal efficiency exhibited concentration-dependent characteristics. That is, at low initial VOCs concentrations, where adsorption was limited, water molecules competed with VOCs for adsorption sites, leading to inhibited removal rates. This inhibitory effect intensified with increasing initial water content. In contrast, at high initial VOCs concentrations, the adsorption capacity of TiO2 increased significantly. Moreover, water molecules promoted the generation of hydroxyl radicals (·OH), thereby enhancing the removal efficiency of VOCs. In binary-component systems (ethanol-benzene mixture), competitive adsorption at low concentrations resulted in mutual inhibition of removal rates for both compounds. As the initial VOCs concentration increased, the adsorption capacity of TiO2 expanded. Under these conditions, benzene had no significant impact on the removal rate of ethanol, while ethanol effectively enhanced the removal rate of benzene by providing additional ·OH radicals. This study demonstrates that the adsorption behavior of VOCs on photocatalysts is a core factor determining their removal efficiency. The effects of water vapor and component interactions are highly dependent on the initial VOCs concentration and the resulting adsorption state. These findings provide important theoretical insights for optimizing the photocatalytic treatment conditions of complex VOCs systems under the "Dual Carbon" framework.
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