Insights into the synergistic role of catalytic ceramic membranes for ozone and peroxymonosulfate activation towards effective recalcitrant micropollutant degradation and mineralization

Abstract This work evaluated the application of catalytic ceramic membrane (Me-CCM, Me = Ce or Co) functionalized with Me-doped TiOx catalytic filtration layer and MeOx nanocatalysts impregnated substrate in the Hybrid Oxidation Separation Technology (HOST) for recalcitrant micropollutant (MP) degradation. The architectural design of the Me-CCM was aimed to enhance the oxidant utilization for the targeted MP degradation and mineralization via the synergism of membrane separation and advanced oxidation process (AOP) within the hybrid membrane reactor. The self-cleaning property of the Me-CCMs was first investigated with humic acid as foulant. A series of comparison studies was conducted with the Me-CCMs employed for degradation of a MP mixture (bisphenol A (BPA), benzotriazole (BTA), clofibric acid (CA), N,N-diethyl-m-toluamide (DEET) and sulfamethoxazole (SMX)) in the HOST process operated under a continuous dead-end filtration mode and dosed with O3 or peroxymonosulfate (PMS). The Ce-CCM/O3 HOST process could effectively degrade and mineralize the MPs with a low specific oxidant consumption of 0.7 M O3(aq) M−1 TOC removal, whereas the Co-CCM/PMS HOST process exhibited selective BPA and SMX degradation. The reactive oxygen species (ROS), including HO•, O2•−, SO4•− and 1O2 were identified by electron paramagnetic resonance spectrometer (EPR), ROS scavenging and molecular probing experiments. The robustness of the HOST system was tested with real water matrices obtained from the local water treatment and reclamation plants. The bromate formation potential was also investigated in the hybrid processes, in which the short contact time within the Me-CCM porous structure could effectively inhibit the bromate formation.