The degradation of BPA on enhanced heterogeneous photo-Fenton system using EDDS and different nanosized hematite

Photo-Fenton processes have been widely studied in wastewater treatment. In this research, the degradation of bisphenol A (BPA) was carried out in a new heterogeneous photo-Fenton process. The ethylenediamine-N,N'-disuccinic acid (EDDS) was used as chelating agent in this system with two different kinds of commercially available nanosized hematite (30 nm and 80 nm) addition. The results showed that the present of EDDS could enhance the degradation efficiency. And can be concluded that the degradation efficiency is better in the system with 30 nm hematite. The TEM, XRD, and specific surface area were conducted to understand the different characteristics of the two size hematite. The adsorption experiments of BPA and EDDS on hematite proved that there was little adsorption of BPA while the EDDS was adsorbed much more on hematite, which has confirmed Fe(III) and EDDS can form Fe(III)-EDDS complex. The effects of different parameters including hematite loading, H₂O₂, and EDDS concentrations on the degradation process were investigated. According to the results, the optimum condition for BPA degradation using 30 nm (0.8 g L^-1 hematite, 0.1 mmol L^-1 H₂O₂, and 1.2 mmol L^-1 EDDS) and 80 nm (0.6 g L^-1 hematite, 0.05 mmol L^-1 H₂O₂, and 1.2 mmol L^-1 EDDS) hematite were selected. It was confirmed that the ·OH plays an important role in the oxidation process through attacking the BPA molecule and produce hydroxyl addition derivative. In addition, O₂ can react with electron (e^-) and holes (h⁺) produced by iron oxide under UV irradiation to create ¹O₂, which could work as potential reactive species to oxidize BPA.