Photo-Fenton-like degradation of bisphenol A by persulfate and solar irradiation

This work evaluates the feasibility of a solar-enhanced Fenton-like process using S2O82− (PS) and Fe2+ for the elimination of BPA, a model endocrine-disruption compound. This comparative study of BPA removal showed that among the approaches employed, the effectiveness of BPA degradation (10 mg/L) decreased in the order: Solar/PS/Fe2+> Solar/PS > PS/Fe2+> Solar/Fe2+> Solar. The complete degradation of BPA was achieved by Solar/PS/Fe2+ treatment at a [PS]:[BPA] ratio of 20 in less than t30W 5 in deionised water. The high efficiency of the Solar/PS/Fe2+ process revealed a synergistic effect (ϕ = 2.38) between the applied activation agents on the formation of reactive oxygen species (ROS) and subsequent decomposition of BPA. The treatment was accompanied by total organic carbon (TOC) removal (44%) in 45 min. Sequential generation of reactive oxygen species has made Solar/PS/Fe2+ a kinetically effective process for removing BPA without accumulation of toxic intermediates. The reaction rate followed pseudo-first-order kinetics that increased with increasing PS and Fe2+ concentrations. Experimental evidence suggests that exposure to solar irradiation maintains suitable quantities of free Fe2+ in the reaction mixture, even at low catalyst concentrations (the molar ratio of [PS]:[Fe2+] varied from 1:0.01 to 1:0.08). The effects of HCO3−, SO42−, and Cl− were also examined. As expected, HCO3− and SO42− inhibited BPA oxidation. The effect of Cl− on the oxidation efficiency of BPA in Fenton-like systems depends not only on actual Cl− concentrations but it is also highly influenced by molar ratios of Cl− to oxidant and catalyst. Inhibition, which was caused by Cl− in the mM range can be overcome by prolonging the reaction time or increasing the initial Fe2+concentration. Finally, the efficiency of Solar/PS/Fe2+ process was examined in diluted natural surface water and wastewater effluent. On eliminating the buffering action of HCO3−/CO32− ions by lowering the pH value to 4.5, complete BPA degradation was achieved in all real water matrices. [Display omitted]