Novel GO/OMWCNTs mixed-matrix membrane with enhanced antifouling property for palm oil mill effluent treatment

Membrane process is considered an effective and economical treatment technology to palm oil mill effluent (POME) which is a major pollution source discharged from the palm oil industry. In this study, graphene oxide (GO) and oxidized multi-walled carbon nanotubes (OMWCNTs) were used as nano additive in coagulation bath to prepare polyvinylidene fluoride (PVDF) membrane via in-situ colloidal precipitation method. The successful synthesis of carbon nanomaterials GO and OMWCNTs were validated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and observed using field emission scanning electron microscopy (FESEM). In general, incorporation of GO and OMWCNTs into membrane matrix via in-situ colloidal precipitation method have significant effect on membrane characterization including contact angle, surface charge, porosity and pore size of the membrane. As observed using FESEM images, GO nanosheets had blocked some areas of the membrane surface thus reducing the effective filtration area. The mixed-matrix membranes M1c, M3a, and M5b demonstrated improved water permeability of 43.99 L/m2·h·bar, 52.62 L/m2·h·bar, and 43.38 L/m2·h·bar, respectively owing to thinner skin layer, bigger voids, and increased hydrophilicity. The rejection performance of fabricated membrane was evaluated using diluted aerobic POME on physical characteristics (color, turbidity, total suspended solids (TSS), total dissolved solids (TDS), pH) and chemical properties (chemical oxygen demand (COD), hardness, total chlorine, and phosphorus). As compared to pristine membrane, the mixed-matrix membrane, M1c had improved the rejection of TDS, phosphorus, hardness, COD, chlorine, turbidity, color, and TSS with maximum rejection percentage of 1.51%, 6.55%, 21.79%, 75.5%, 76%, 81.94%, 86.3%, and 100%, respectively. This research demonstrated that the deposition of carbon nanomaterials increased the membrane hydrophilicity and formed a repulsive boundary barrier that enhanced antifouling properties.