Controlling the Gas–Water Interface to Enhance Photocatalytic Degradation of Volatile Organic Compounds

The gas–water interface plays an important role in the photocatalytic degradation of volatile organic compounds (VOCs). Herein, a novel photocatalytic reactor with a tunable gas–water interface was designed and utilized to investigate the performance of photocatalytic degradation of VOCs. The relationship between the key operating parameters of the reactor and VOCs mineralization was investigated in detail with toluene as a model pollutant. The results showed that a tunable gas–water interface was formed in the process of atomized spray photocatalytic oxidation. Furthermore, the photocatalyst was easily excited by light, generating more free radicals, which was conducive to improving the mineralization performance of toluene and the durability of the catalyst. The intermediates of the toluene reaction were analyzed by photoacoustic spectroscopy (PAS), total organic carbon (TOC), and electrospray ionization–ion trap mass spectrometry (ESI–MS). The results show that abundant hydroxyl radicals are formed at the gas–water interface, which is beneficial to the opening of the benzene ring and greatly reduces the formation of toxicity and byproducts. Simultaneously, we investigated the degradation performance of acetone, formaldehyde, and n-hexane in the reactor. This provides a new strategy for using photocatalytic technology to purify industrial flue gas and indoor air.