Fabrication of Cementitious Microfiltration Membrane and Its Catalytic Ozonation for the Removal of Small Molecule Organic Pollutants

Abstract

In this study, a low-cost cementitious microfiltration membrane (CM) with a catalytic ozone oxidation function for the removal of organic pollutants was fabricated by using cementitious and C-10 μm silica powders at a certain silica–cementitious particle ratio (s/c). The effect of the s/c on the pore size distribution and mechanical strength of the membrane was investigated. The membrane pore size showed a bimodal distribution, and the higher the s/c, the closer the second peak was to the accumulated average particle size of silica. The increase in the s/c led to a decrease in the bending strength of the membrane. The cross-sectional morphology by SEM and crystal structure by XRD of CMs confirmed that a calcium silicate hydrate gel was generated around the silica powder to improve the mechanical strength of the CM. Considering the bending strength and pore size distribution of CMs, s/c = 0.5 was selected as the optimal membrane fabrication condition. The FT-IR results characterizing the surface functional groups of CMs were rich in surface hydroxyl groups with the ability to catalyze ozone oxidation for organic pollutant removal. Six small molecule organic pollutants were selected as model compounds for the efficiency experiments via a CM–ozone coupling process to prove the catalytic property of the CM. The CM has an alkaline buffering effect and can stabilize the initial pH of the solution in the catalytic ozonation process. The reuse experiments of the CM–ozone coupling process demonstrated the broad spectrum of the CM catalytic performance and self-cleaning properties. The results of this study provide the basis and experimental support to expand the practical application of CMs.

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“…In the first study, from cementitious powders and amorphous silica (C-10 µm), Sun et al [ 1 ] developed a cementitious microfiltration membrane (CM) with a catalytic ozone oxidation function for the removal of organic pollutants. By increasing the silica–cement ratio (s/c) the authors observed that the membranes showed an increase in pure water flux (PWF) and a decrease in mechanical strength.…”