Surface modification of GO/PVDF composite membrane by MXene/protonated g‐C₃N₄ nanosheets hybrids with improved dye separation and antifouling properties

Abstract

AbstractGraphene oxide‐polyvinylidene composite membranes were fabricated via the phase inversion technique. Then, GO‐PVDF membrane with highest water flux was achieved via surface modification with 2‐D MXene and 2‐D MXene /protonated 2‐D g‐C₃N₄ nanosheets hybrid via vacuum filtration of an aqueous dispersion of MXene and MXene‐protonated g‐C₃N₄ nanosheets hybrid, respectively, on GO‐PVDF membrane support to improve filtration efficiency and antifouling properties. The membranes were designated as MXene/GO‐PVDF (M2) and MXene‐protonated g‐C₃N₄/GO‐PVDF(M3). XRD, SEM, and FTIR analysis were used for characterization. The results showed that the performance of both MXene /GO‐PVDF and MXene‐ Pg‐C₃N₄/GO‐PVDF membranes was improved significantly in removing cationic dyes, unlike anionic pigments. Also, the resistance of these membranes against fouling has improved. The MXene‐ Pg‐C₃N₄/GO‐PVDF shows a significant enhancement in the removal of crystal violet (CV) cationic dye (100%) compared to the pristine membrane (84%) after 4 h of the filtration process. Tests also were performed to remove another two cationic dyes Methylene blue (MB), Rhodamine B (RB), and an anionic dye Methyl‐orange. The anionic dye separation rate from the stream did not show significant improvement while cationic dyes show significant enhancement in separation efficiencies. Modified membranes exhibit an enhancement of fouling resistance properties compared to pristine membranes.Highlights The water contact angle decreased from 71 to 45, which means hydrophilicity improved successfully. Membrane fouling resistance was improved around 15%–20%. PVDF membrane was prepared and graphene oxide was added to the matrix to modify the bulk properties. MXene and C3N4 were synthesized successfully. Surface modification of the PVDF membrane was successful by MXene and C3N4.