A hydrophilic near dissolved organic matter microfiltration (NDOM MF) membrane prepared using multifunctional porogen synthesized via metal-free atom transfer radical polymerization for highly efficient microplastic removal

Microplastic (MP) pollution has emerged as a global concern. One of the practical alternatives is a microfiltration (MF) process using MF membranes with a high MP removal rate and high water permeability simultaneously. In this study, we developed a highly permeable PVC-based MF membrane capable of effectively separating MP by using amphiphilic PVC, which can serve as a pore-forming agent during phase separation and as a hydrophilic modifier after solidification. We developed a new organic photocatalyst under UV light to synthesize amphiphilic PVC via metal-free atom transfer radical polymerization. With 3 wt% amphiphilic PVC, the mean pore size increased to 0.86 µm, which was 3 times larger than the control PVC membrane (0.25 µm). Furthermore, the modified PVC (m-PVC) membrane reduced the contact angle of the membrane from 80.6° to 58.3°, indicating a significant improvement in the hydrophilicity of the membrane. The larger pores and increased hydrophilic properties made the m-PVC membrane 15 times more permeable than the control, while still maintaining a removal rate of approximately 99.9 % in a water filtration test with a 1 µm bead solution. The modified PVC membrane also operated consistently under varying pH conditions. Lastly, the m-PVC membrane exhibited a 12 times lower transmembrane pressure than the control during the constant flux filtration test, resulting in a 5 times lower specific filtration energy despite a 2 times longer filtration time. We hope this study could contribute to creating a new trend in MP removal utilizing a highly porous MF membrane, which is cut out for highly efficient removal of particulate pollutants and high water permeability simultaneously.