A comprehensive study on the performance and antifouling enhancement of the PVDF mixed matrix membranes by embedding different nanoparticulates: Clay, functionalized carbon nanotube, SiO₂ and TiO₂

To design a highly permeable and fouling resistance ultrafiltration (UF) membrane from polyvinylidene fluoride (PVDF), one approach is the incorporation of hydrophilic nanofillers in membrane matrix to modify the hydrophilicity, porosity and pore size of the membrane, and open up the channels for water transport. However, many nanoparticulates with different structures and characteristics were applied for these purposes. In this study, we tried to select the best nanomaterial among the used famous nanomaterials for modifying PVDF based membranes. We have fabricated PVDF mixed matrix membranes (MMMs) consisting of cloisite 30B clay, carboxyl-functionalized multi-walled carbon nanotubes (MWCNTs-COOH), SiO₂ and TiO₂. As a result, the pure water flux (PWF) across the MMMs was significantly improved. The PWF enhancement for clay, MWCNTs-COOH, TiO₂, and SiO₂ embedded MMMs as compared with the pristine PVDF membrane was 187%, 143%, 111%, and 50%, respectively. However, higher loading of the nanoparticulates may result in agglomeration and reduce the separation performance. The breaking elongation of the membranes was reduced by incorporating of the optimum amount of the nanoparticulates. The MMMs showed superior antifouling properties as compared with the pristine membrane owing to the hydrophilicity enhancement by the addition of the nanoparticles. Based on the results, the membrane containing 0.2 wt% MWCNTs-COOH showed the best performance with 135% PWP improvement, nearly 100% bovine serum albumin (BSA) rejection, 33% flux recovery ratio enhancement and lowest breaking elongation reduction. In addition, the used amount of this nanomaterial was lowest, which it could be important from an economical view.