Assembling CoAl-layered metal oxide into the gravity-driven catalytic membrane for Fenton-like catalytic degradation of pharmaceuticals and personal care products

Application of peroxymonosulfate (PMS)-based Fenton-like heterogeneous catalysis in water treatment remains scarce due to mass transfer limitation and poor yield of reactive oxygen species (ROS). Herein, assembling reactive CoAl-layered metal oxide (LMO) into the gravity-driven catalytic membrane was carried out to overcome the inherent limitations. Indeed, compared to the conventional batch reactor (less than 35% removal), the LMO membrane/PMS system achieved effective degradation (94.17%) of the probe chemical ranitidine along with several other selected pharmaceuticals and personal care products (PPCP, >80%). This, as predicted by density functional theory calculations, could be attributed to remarkable activation of PMS by the exposed (001) surfaces and (100) edges of CoAl-LMO, spontaneously generating ROS for PPCP degradation. Electron charge density difference analysis estimated efficient charge accumulation and depletion between PMS and LMO, implying strong interaction and charge transfer in the LMO membrane/PMS system. Notably, ROS quenching experiments and electron paramagnetic resonance spectroscopy confirmed the theoretical findings, which showed that PPCP degradation in the LMO membrane/PMS system is caused by both the radicals (SO4•− + •OH = 51.97%) and nonradicals (1O2 = 20.58%) pathways. The LMO membrane achieved long-term stable performance (>90% removal), and the analysis of the used membrane suggested an increase in the relative distribution of oxygen vacancies or ≡Co–OH species, which is favourable for PMS activation. Overall, this study offers a simple strategy for efficient removal of several PPCPs, which could be applied sustainably in water treatment.