Heterogeneous Photoreaction of Tetrachloroethene—Air Mixture on Halloysite Particles

摘要

The heterogeneous photodegradation of tetrachloroethene in air proceeded on clay particles (halloysite) under photoillumination (>300 nm) with an induction period. The induction period and the tetrachloroethene removal rate were not sensitive to the tetrachloroethene partial pressure or the relative humidity. The photodegradation of tetrachloroethene was accelerated by the reaction with the released Cl atoms. Several tentative photoreaction mechanisms such as that via the tetrachloroethene-oxygen molecule charge-transfer complex were proposed based on the diffuse reflectance UV-vis spectra and the physical properties of the halloysite particles. The photoreaction rate was estimated on the basis of a simulated calculation, which can reproduce the tetrachloroethene initial pressure dependence versus time for tetrachloroethene and its degradation products.