New insights into interfacial interaction and nanoconfinement effect in synergistic oxidation-filtration via CoFe2O4-ceramic membrane activated peroxymonosulfate

Abstract

Ceramic membranes incorporating CoFe2O4 (CoFeCM) were synthesized to activate peroxymonosulfate (PMS), and the performance and mechanisms of its oxidation-filtration were comprehensively investigated. The catalytic filtration performance of CoFeCM/PMS was evaluated by degradation of organic pollutants and the mitigation of membrane fouling. Results indicated that CoFeCM/PMS effectively removed toxic micropollutants, including phenol (82.56%), atrazine (93.42%), and carbamazepine (87.40%), ensuring the permeate quality and safety. Also, this synergistic process notably improved the degradation of natural organic matter (NOM) in the secondary effluent and Songhua River water. CoFeCM/PMS filtration effectively mitigated membrane fouling caused by three typical model organics, reducing their irreversible membrane fouling resistance by 70.85–83.62%, and increasing the normalized flux to 48.74–82.61%. The membrane fouling derived from two actual water systems was also greatly alleviated by CoFeCM/PMS. Based on the Extended Derjaguin-Landau-Verwey-Overbeek theory analysis, NOM was oxidized by reactive oxide species into hydrophilic small molecular fractions, resulting in remarkably increased repulsive interaction between NOM and CoFeCM surface. Density functional theory calculation results confirmed the nanoconfinement effect in CoFeCM pores, which can slow down the growth of foulants in pores and effectively alleviate irreversible membrane fouling. Consequently, standard blocking transformed into the dominant membrane fouling pattern due to the synergistic effects of nanoconfinement catalysis (in membrane pores) and repulsive interactions (on membrane surface) during oxidation-filtration.