Fabrication and Characterization of Functionalized Cellulose Nanocrystals (CNCs)-Infused Polyethersulfone (PES) Polymer Membrane for Enhanced Antifouling Property

One promising approach to fouling reduction in membrane technology is through the fabrication of multi-component hybrid membranes, in which the secondary component, commonly inorganic nanoparticles is incorporated and embedded uniformly into the polymer matrix. For the first time, cellulose nanocrystals (CNCs) functionalized with cetyl-trimethylammonium bromide (CTAB) were embedded into the polyethersulfone (PES) membrane. Cellulose nanocrystals were prepared using a mixed acid system containing a mixture of sulphuric acid, oxalic acid, and water in a ratio of 1:5:4. The nanocomposite nanofiltration (NF) membrane was fabricated by dissolving PES in N-dimethylacetamide (DMAc), after which the functionalized CNCs were added to the mixture and cast using a casting blade, via a phase inversion technique. Characterization techniques, such as Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR), were used to check the surface morphology, the presence of surface functional groups, of the cellulose nanocrystals, and the fabricated membranes, respectively. The water contact angle was used to analyze the hydrophilicity of the membrane. The fabricated membranes were also characterized using a tensile analyzer to evaluate the mechanical properties of the membrane, respectively. SEM analysis showed dense and tight structures for both modified and unmodified membranes. FTIR results revealed the successful attachment of the functional group onto the surface of the CNCs after functionalization. Embedding fCNCs into the membrane decreased the water contact angle (52.63°) of the fCNCs-infused membrane, thereby increasing the hydrophilicity of the membrane, compared to PES/CNCs with a contact angle of 57.4°. The maximum tensile strength measured in this investigation was 10.6954 MPa for PES-fCNC (0.002%). Therefore, the results have shown a great prospect in the development of CTAB-modified CNCs embedded in PES membranes for possible applications in wastewater treatment.