The photo-catalytic degradation of phenol using TiO₂ as the catalyst and the effect of metal ionic reaction additives

The effects of additive metal ions on photo-catalytic oxidation (PCO) of phenol in aqueous solution was studied on a bench scale using TiO₂ and UV as the PCO system. It was considered that ferric ion (Fe³⁺) and ceric ion (Ce⁴⁺) could increase the efficiency of degradation of phenol in PCO reaction, only if Fe³⁺ and Ce⁴⁺, as electron acceptors, could prevent the recombination of hole-electron in the surface of TiO₂. From the quantitative investigation, it was found that ferric ion increased the efficiency of degradation of aqueous phenol during PCO reaction, with concentration range of [Fe³⁺] = 0.1–0.3 mM. Especially, in case of 0.2 mM of ferric ion, the reaction time for the complete destruction of aqueous phenol decreased to 1/3 of the control case (i.e. 150 min →50 min). However, ceric ion (Ce⁴⁺) was rarely effective with concentration range of [Ce⁴⁺] = 0.02 mM, but, still showed the possibility of electron acceptors.