Heterogeneous degradation of organic contaminants in the photo-Fenton reaction employing pure cubic β-Fe2O3

The photo-Fenton reactions mechanisms with β-Fe2O3 and mechanism of phenol oxidation were shown in the above figure. In β-Fe2O3/H2O2/light system, the dye was excited into dye+ under visible light and the resulting electron was transferred to the surface of the β-Fe2O3 to reduce the ΞFe3+ into an ΞFe2+, ΞFe2+ will react with H2O2 to produce more OH for the degradation of organic matter and the resulting ΞFe3+ will continue to be recycled (the yellow indicator lines indicated that it was likely to occur). Although benzoquinone often acted as the scavenger of O2, the experimental results showed no degradation of benzoquinone in the β-Fe2O3/light system. It suggested that O2 was not produced in the β-Fe2O3/light system (The black indicator lines indicated almost no occurrence). Hydroxylation of phenol generated catechol, hydroquinone, resorcinol, carboxylic acids, aldehydes, phloroglucinol, oxalic acid, carboxylic acids with hydroxyl group, 1,2,4-benzenetriol, maleic acid, p-Quinone and small molecule carboxylic acids as the major intermediates, which were converted into H2O and CO2 eventually. This process will have a positive effect on industrial wastewater treatment.