Adsorption and aggregation of Fe(III)-hydroxy complexes during the photodegradation of phenol using the iron-added-TiO2 combined system

The behavior of Fe(III) aquacomplexes in TiO2 suspensions in the degradation of phenol has been investigated. The most active Fe(OH)2+ species adsorbed on the surface of TiO2 retards the conversion of Fe(OH)2+ into oligomers and therefore increases the percentage of Fe(OH)2+ with irradiation time, with a consequent enhancement in the catalytic cycle of Fe(III)/Fe(II) and excited charge traps by Fe(III) in the iron-TiO2 system. The influence of iron addition on TiO2 was obtained when the regeneration of [Fe(OH)2+] remained continuous with irradiation time. In an optimum TiO2 suspension (0.5 g/L) with the addition of 0.1 mM Fe(III), the measured kobs values for phenol degradation were enhanced for the higher adsorption of Fe(OH)2+ on the reactive surface of TiO2 at a specified irradiation time.