Interfacial reactions of catalytic ozone membranes resulting in the release and degradation of irreversible foulants

Abstract

An efficient in-situ self-cleaning catalytic ceramic-membrane tailored with MnO₂-Co₃O₄ nanoparticles (Mn-Co-CM) was fabricated. Density functional theory calculations result substantiated that molecular ozone could be effectively adsorbed by oxygen vacancies (OV) on the Mn-Co-CM surface and then direct activated into a surface-bound atomic oxygen (*O_ad) and a peroxide (*O_{2, ad}), ultimately producing ^·OH. Mn-Co-CM coupling with ozone efficiently removed foulants from the permeate and the membrane surface simultaneously and leading to in-situ formation of ^·OH that changed the nature of the irreversible foulants and ultimately resulted in the rapid release and degradation of humic acid-like substances causing irreversible fouling. However, the commercial CM with ozone mainly removed cake layer fouling including protein-like and fulvic acid-like substances, followed by the slow release and degradation of irreversible foulant, resulting in many humic acid-like substances remain on the membrane surface as irreversible fouling. Based on these, the flux growth rate of Mn-Co-CM was 3.5 times higher than that of CM with ozone. This study provides new insights into the mechanism of in-situ membrane fouling mitigation, when using an efficient catalytic ceramic-membrane. This will facilitate the development of membrane antifouling strategies.

Keywords: Catalytic ozonation membrane; Density functional theory; Membrane fouling; MnO(2)–Co(3)O(4); Two-dimensional correlation spectroscopy.