Effect of oxalate on photodegradation of bisphenol a at the interface of different iron oxides

In this study, a series of experiments were conducted to investigate the effect of the properties of iron oxides and oxalate on the degradation of bisphenol A (BPA) as a model organic pollutant in aqueous solution under UV illumination. Three iron oxides (Magh-300, Hem-420, and Hem-550) were prepared by a hydrothermal process and characterized by X-ray diffraction, the Brunauer-Emmett-Teller method, and scanning electron microscopy. The experimental results confirmed that the existence of oxalate can greatly enhance the BPA degradation reaction on the iron oxides in aqueous solution compared to iron oxides alone. The properties of iron oxides influenced strongly the dependence of the BPA degradation on the oxalate concentration. The optimal initial concentrations of oxalate were determined to be 2.4, 2.4, and 0.6 mM for Magh-300, Hem-420, and Hem-550, respectively. The optimal pH value was found to be 3.93, 3.64, and 3.61, for Magh-300, Hem-420, and Hem-550, respectively. The rate of BPA degradation on different iron oxides with oxalate under UV illumination can be ranked as Magh-300 > Hem-420 > Hem-550. Furthermore, it was found that the dependence of BPA degradation is also attributable to the interaction between iron oxide and oxalate, and the formation of dissolved Fe in the solution or adsorbed Fe-oxalate species on the surface of iron oxides.