- Thesis topic: Simultaneously Photocatalytic and Peroxysulfate Activation Processes by CuO@TiO2 Photocatalyst Coating on PVDF Membrane for Degradation of Membrane Fouling

- Doi: https://doi.org/10.6840/cycu202301530

- Abstract: 

        Membrane processes are widely used in water treatment technology, but they suffer from fouling issues that affect their flux and lifespan over prolonged operation. In recent years, the combination of photocatalysis and peroxymonosulfate (PMS) activation has been recognized as a promising approach for organic pollutant degradation, making it a prospective water purification technology. Therefore, in this study, we aimed to modify polyvinylidene fluoride (PVDF) membranes using a synthesized composite photocatalyst (CuO@TiO2) and utilize photocatalytic reactions and PMS activation to mitigate membrane fouling.The CuO@TiO2 photocatalyst was coated onto PVDF membranes using a coating method, and PMS was activated to generate reactive free radicals. The modified membranes were then tested for their anti-fouling performance and flux recovery rate through simulated pollutant testing. The photocatalytic performance of different compositions of CuO@TiO2 was initially evaluated to determine the optimal composition for membrane incorporation. Experimental results revealed that the 25% CuO@TiO2 composite exhibited the highest photocatalytic degradation efficiency, with a final removal efficiency of 38.44% after 70 minutes of UV photocatalysis at a dye concentration of 20 mg/L. The addition of PMS further increased the removal efficiency to 89.61%. Furthermore, the composite photocatalyst was characterized using techniques such as FTIR, SEM-EDS, TEM, XRD, BET, UV-Vis DRS, XPS, ESR, and AFM, revealing that the prepared CuO@TiO2 possessed low bandgap, high specific surface area (60.65 m2/g), small particle size (30-50 nm), and small pore size (2-4 nm).
          During the five-cycle testing of the membranes, the degradation efficiency decreased from 62% in the first cycle to 40% in the fifth cycle, indicating a slight decline in stability. However, in low concentration dye solutions, the degradation efficiency remained at 100%. Although the modified photocatalytic membranes exhibited a reduction of approximately 25% in pure water flux compared to pristine PVDF membranes, the average flux remained significantly higher than other hydrophobic membranes, demonstrating its high flux performance and stability. After anti-fouling testing, the modified photocatalytic membrane 25% CuO@TiO2/PAA/PVDF showed excellent anti-fouling performance with a membrane flux recovery rate (FRR%) of 98.9% for sodium alginate as a simulated pollutant, and a flux recovery rate of 94.7% for bovine serum albumin. These results indicate that the modified photocatalytic membrane 25% CuO@TiO2/PAA/PVDF has high applicability in wastewater filtration and separation processes.

Keywords: Photocatalysis, composite photocatalyst, CuO@TiO2, peroxymonosulfate (PMS), polyvinylidene fluoride (PVDF), anti-fouling membrane