Photocatalytic Hydrodechlorination of Trace Carbon Tetrachloride (CCl4) in Aqueous Medium

The technical feasibility of the photocatalytic hydrodechlorination of CCl4 utilizing H2 produced in situ from photocatalytic water splitting was investigated using multifunctional Pd–NiO/NaTaO3:La catalysts and a O/NaTaO3:La + Pd–Au/IX (ion-exchange resin) mixture-of-catalysts approach. In the former case, the incorporation of Pd into the water-splitting photocatalyst resulted in the reduction of H2 evolution by 3 orders of magnitude. However, the multifunctional catalyst exhibited a remarkable activity for CCl4 removal. The important catalyst parameters were elucidated by the response surface methodology. The Ni and Pd loadings and the catalyst reduction temperature had significant, nonlinear effects on the catalyst activity, indicating that both NiO and Pd nanoparticles play important roles in the photocatalytic hydrodechlorination of CCl4. The strong dependence of the turnover frequency on the catalyst parameters that govern the dispersion of the catalytic phases implies that the reaction is structure-sensitive.