Heterogeneous photocatalytic reduction of ferrate(VI) in UV-irradiated titania suspensions

The heterogeneous photocatalytic reduction of Fe(VI) in UV-irradiated TiO2 suspensions was conducted in a basic media. Fe(VI) reduction as a function of TiO2 suspensions, Fe(VI) concentrations, and pH was studied. The initial rate of Fe(VI) reduction adheres to the simple Langmuir-Hinshelwood kinetics. This and the fractional order with respect to initial Fe(VI) concentrations suggests that the surface reaction is the rate-controlling step. The photocatalytic oxidation of ammonia using TiO2 in the presence and absence of Fe(VI) was also investigated at pH 9.0. Enhancements in the rates of ammonia oxidation and Fe(VI) reduction were observed. The results indicate the formation of Fe(V) by a TiO2 conduction band electron. Fe(V) selectively and rapidly oxidizes compounds; therefore, production of Fe(V) by a photocatalytic technique has a role in synthesis and remediation processes.