- Thesis topic: Incorporation of catalysts into traditional filtration membranes for antifouling performance: The key role of copper in the composite catalysts

- Doi: https://doi.org/10.6840/cycu202301349

- Abstract: 

        Traditional wastewater filtration membranes have long been commercialized and widely applied in practice. However, manufacturers and researchers are constantly improving these traditional membranes to limit their shortcomings as well as meet the increasing requirements for their performance, durability, and economy. Conventional membranes are usually composed of organic polymers that are less hydrophilic or hydrophobic, so the problem in their practical application is the phenomenon of membrane fouling. In addition, their hydrophobicity is also the reason why water permeate flux is so low that their effectiveness is not as expected. Therefore, within the scope of this study, we have utilized different synthesized catalysts to modify these conventional membranes to mitigate membrane fouling. These inorganic catalysts both act as a hydrophilic layer on the membrane surface and catalyze the decomposition of foulants. The catalysts used in this work are copper-containing composite catalysts such as catalytic wet-air oxidation (CWAO) catalysts or photocatalysts. The CWAO catalysts are mixed metal oxides of elements such as Zn, Cu, and Fe with optimized composition. The synthesized photocatalysts include Cu@ZrO2, Cu@TiO2, and CuO@TiO2. We integrated these catalysts with PES (polyethersulfone) membranes using both blending and coating methods to evaluate the effect of the membrane fabrication method on antifouling properties. In particular, an intermediate adhesive layer has been used in the coating method: PAA (polyacrylic acid) to create the binding between the membrane surface and inorganic catalysts. The catalysts have been evaluated for their catalytic performance to degrade model contaminants to find their optimal composition before they are incorporated into the membranes. Besides, the catalysts are also characterized by advanced methods such as FTIR, SEM-EDS, TEM, XRD, BET, UV-Vis DRS, XPS, ESR, etc. The performance of modified membranes has been evaluated by membrane filtration test, antifouling test, surface roughness parameters, etc. The decomposition mechanism of the model pollutant is also well explained by theoretical calculations based on DFT. The results showed that the catalysts were successfully synthesized with high pollutant degradation efficiency (> 88%) and high surface area (> 50 m2/g). The modified membranes have good antifouling properties (FRRs > 90%) and stable pollutant decomposition performance over five consecutive evaluated cycles. The permeability of modified membranes is much higher than that of pristine membranes for the blending method but almost negligible for the coating method. Thereby, it shows that membrane modification by the catalysts synthesized in this study is feasible and may initiate further studies and applications.

Keywords: Water and wastewater treatments, Membrane filtration, Membrane modification, CWAO catalysts, Photocatalysts, Catalytic membranes, Antifouling membranes