Polyhexamethylene guanidine functionalized chitosan nanofiber membrane with superior adsorption and antibacterial performances

Although various nanofiber membranes have been developed for sewage treatment, only a few membranes possess antibacterial activities. Thus, poly-hexamethylene guanidine (PHMG) with broad-spectrum antimicrobial activity was used to functionalize the oxidized chitosan (OCS) nanofibers in solid state. Scanning electron microscope (SEM) investigation indicated that polyvinyl alcohol (PVA) introduced leads to the significantly improved spinnability. Fourier transform infrared spectroscopy (FTIR) and elemental analysis indicate that the as-proposed solid phase grafting strategy is successful and the graft ratio of PHMG is about 36.5%. As expected, PHMG grafted can significantly enhance the antibacterial activity of OCS-PVA nanofibers, but leads to the decrease of the specific surface area and total pore volume. Further adsorption analysis shows that the adsorption capacities of the PHMG-OCS-PVA fiber membrane for Cu(II) and Congo red are 57.0 mg g−1 and 183.3 mg g−1, respectively. Kinetic and isotherm model studies indicate that the pseudo second-order kinetic and Freundlich models can well match the adsorption process of Cu(II) and Congo red. The PHMG-OCS-PVA fiber membrane also shows excellent selectivity towards the separation of various anionic dyes from an aqueous dye mixture. In conclusion, the as-fabricated PHMG-OCS-PVA fiber membrane may be used as a new sewage treatment membrane with superior anti-biofouling performance.