Efficient degradation of carbamazepine by dual-wavelength UV enhanced E-peroxone process: Kinetics and mechanism

Given the limitations of unequal H2O2 and O-3 distribution in the E-peroxone (EP) process, a novel dual-wavelength UV enhanced E-peroxone process (VUV/UVC/EP) with high performance for removing emerging contaminants was established. In this paper, carbamazepine (CBZ) removal rates by different oxidation processes were investigated, calculating the kinetic effects of the VUV/UVC/EP processes in various operating parameters, and the degradation mechanisms and pathways of CBZ were comprehensively discussed. Compared with conventional EP, ultraviolet (UVC, wavelength 254 nm), UVC/EP, and dual-wavelength ultraviolet (VUV/UVC, wavelength 185 and 254 nm) processes, the VUV/UVC/EP process exhibits an excellent ability for degradation of carbamazepine (CBZ), the synergy coefficient between VUV/UVC and EP process is 1.44 (>1). In particular, the VUV/UVC/EP process exhibits exceptional degradation performance even at 50 mg L-1 CBZ. It also demonstrates high adaptability to varying pH, humic acid concentration, and different inorganic anions (SO42-, Cl-, NO3-, PO43- and CO32-). In addition, <middle dot>OH, O-1(2), and<middle dot>O-2(-) were identified to exist in the VUV/UVC/EP process. The dominant reactive species <middle dot>OH content was increased by decomposing the excess dissolved O-3 to accelerate CBZ degradation. CBZ was broken down into a series of intermediates, NO2-, NO3-, and other inorganic compounds through ring reduction and oxidation reactions under the attack of reactive oxygen species (ROS) generated in the VUV/UVC/EP process. It also can remove more than 50% of TOC in 30 min and decrease biological toxicity. An electrical energy-per-order (EEO) value of 3.37 kW h m(-3) indicated that the VUV/UVC/EP process is economically feasible. This comprehensive examination provides valuable insights into the CBZ removal in reclaimed water, contributing to the advancement of environmental water resources.