Heterogeneous Catalysis of the Photodegradation of Chloroform

The ability of five substances – Amberlite IRA-900 anion exchange resin in the Cl- form, CuCl4 2- supported on Dowex 2-X8 anion exchange resin (CuCl4 2-/Dowex), FeCl4- supported on Dowex 2-X8 (FeCl4-/Dowex), FeCl3 supported on silica gel (FeCl3/SiO2), and unmodified MCM-41 mesoporous silica – to catalyze the photodecomposition of chloroform to COCl2 and HCl in a suspension irradiated under oxygen at wavelengths above 345 nm was compared, choosing amounts of each catalyst to optimize the decomposition rate. Amberlite, FeCl4-/Dowex, and MCM-41 were the most active. The same comparison was made for chloroform irradiated under air by sunlight, for which Amberlite, CuCl4 2- /Dowex, and MCM-41 were the most active. After irradiation, all samples had a COCl2 to HCl ratio greater than 10:1. A photodecomposition mechanism different from that observed in the gas phase is proposed that includes the participation of trichloromethylhydroperoxide.