Solar photo-Fenton like using persulphate for carbamazepine removal from domestic wastewater

Abstract

This work aimed at decontaminating biologically treated domestic wastewater effluent from pharmaceutical residues by using sulphate radical based homogeneous photo-Fenton involving persulphate (PS) as an oxidant, ferrous iron (Fe(II)) as a catalyst and simulated solar irradiation as a light source. This is the first time that the beneficiary use of solar energy in PS/Fe(II)/UV-Vis system was evaluated by using carbamazepine (CBZ) as a probe compound. In wastewater, CBZ was fully degraded in 30 min for an initial CBZ concentration of 50 μM and an optimal PS:Fe(II) molar ratio of 2:1 thanks to the high selectivity in reactivity of the sulphate radical limiting scavenging effects of organic matter and inorganic ions. Seventeen by-products were identified using liquid chromatography-high resolution-mass spectrometry allowing for the establishment of degradation pathways. CBZ first underwent degradation through one electron transfer oxidation processes due to sulphate radical reactivity followed by hydroxylation processes through hydroxyl radical formed by Fe(III) photoreduction. The sequential generation of sulphate radical and hydroxyl radical has made PS/Fe(II)/UV-Vis a kinetically effective process in removing CBZ from wastewater without the accumulation of toxic intermediates and opens new remediation strategies for tertiary treatment in domestic wastewater treatment plants.

Keywords: Carbamazepine; Solar photo-Fenton; Sulphate radical; Transformation pathways; Wastewater.