Photoreduction of 1,1,2-Trichlorotrifluoroethane Initiated by TiO₂ Particles

Abstract

Reductive dehalogenation of 1,1,2-trichlorotrifluoroethane (CFC 113) takes place upon illumination of air-free suspensions of TiO2 particles containing formate ions. Chloride ions and 1,2-dichlorotrifluoroethane (HCFC 123a) are the main reaction products. Reaction rates increase with increasing concentration of CFC even beyond the solubility limit of the Freon in water. Evidence is presented that a chain transformation of the Freon takes place in formate solutions. The results are explained assuming that reduction of the Freon proceeds via a radical chain mechanism, which involves participation of CFC and formate species located on as well as next to the oxide surface.

Photoreduction of CHCl3 in Aqueous SPEEK/HCO2– Solutions Involving Free Radicals

“…Included in the inset is a plot showing that the ϕ­(Cl – ) variation was nearly linear with I 0 –1/2 . Similar dependencies were noticed for the photoreductions of CCl 4 , CCl 3 F, and CCl 2 FCClF 2 ,,, and are typical of chain transformations involving radical–radical termination reactions . As for CFC 113, the CHCl 3 dehalogenation was characterized by low quantum efficiencies at all photon fluxes.…”

A surface science perspective on TiO2 photocatalysis

“…Tan et al [1179][1180][1181][1182] have shown that the nature of the sacrificial electron donor is important, with formate showing the most promise. Other photoreduction systems of interest include iodine/triiodide [422,495] and a variety of halocarbons photoreduced through radical chain reactions [1001,[1183][1184][1185].…”

Fighting global warming: The potential of photocatalysis against CO2, CH4, N2O, CFCs, tropospheric O3, BC and other major contributors to climate change

“…Weaver [89] showed that reductive dehalogenation of trichlorotrifluoroethane (CFC-113), took place upon illumination of air-free suspensions of TiO 2 particles containing formate ions.…”