Fabrication of novel poly (vinylidene fluoride) /MWCNT nanocomposite ultrafiltration membranes for natural organic matter removal

Abstract

Poly (vinylidene) fluoride (PVDF) has advantages as a membrane material compared to other commercialized polymeric materials as it is easily dissolved in common organic solvents and its proper asymmetric structure for separation. However, its hydrophobic characteristics lead to low water flux and makes PVDF membrane easily fouled while treating solutions containing natural organic matters. The aim of this research is to enhance the performance of PVDF ultrafiltration membrane by using different additives. In the first part (MWCNT)/ polydopamine (PDA) was used as additives with different MWCNT concentrations. The PVDF membrane blended with a mixture of 2% dopamine/ 1% MWCNT showed 20 folds improvements in permeability in comparison to pristine PVDF ultrafiltration membrane. Furthermore, it demonstrated about 81% rejection for Suwannee River Humic acid (HA) filtration test. In the second part, (PANI) was used as an additive. Two blending methods of aniline were applied, and the synthesized PANI was used as an additive to produce PANI/PVDF modified membranes. Results show that the water permeability and antifouling properties of modified PVDF membranes were both improved. Water permeability of PANI/PVDF modified membranes were 7-16 times greater than pristine PVDF. Finally, MWCNT/PANI/ PVDF ultrafiltration membrane was prepared by phase inversion technique. The resultant membrane of (PANI/ 1.5 % MWCNT) showed the highest permeability results (1320 LMH/bar) among membranes we tested with 40 folds permeability improvement in comparison to pristine PVDF ultrafiltration membrane. Furthermore, it showed about 79% rejection HA filtration test.