Combined antibacterial and antifouling properties of polyethersulfone mixed matrix membranes with zwitterionic graphene oxide nanostructures

The impact of zwitterionic graphene oxide (GO-Arg) nanostructures into polyethersulfone (PES) membranes was studied, aiming to perform mixed matrix membranes (MMMs) with combined antibacterial and antifouling properties. For this purpose, 0.25, 0.50, and 1.0 wt% of GO-Arg were incorporated through the phase inversion method. The chemical composition reveals that the electrostatic interactions of PES, polyvinylpyrrolidone, and GO-Arg occur by enhancing the C-H/N-H vibrations associated with the intrinsic MMMs and their combined antibacterial and antifouling performance. Well-defined finger-like morphology was observed, performing the pore distribution and the finger-cavity inclination induced by the electrostatic charge of GO-Arg. As a result, GO-Arg MMM's hydrophobic properties decreased from 77.8 degrees to 52.3 degrees, inducing a partially hydrophilic surface and improved water flux. The isoelectric point of nanostructured membranes slightly changes by the charge modulation produced by zwitterionic GO-Arg. The antibacterial activity against Gram (-) Escherichia coli was improved, closing the complete bacterial inhibition after 24 h. As a result, antifouling performance was improved, avoiding bacterial adhesion into the membrane surface and the possibility of promoting biofilm formation. Our results demonstrate that zwitterionic nanomaterials in MMMs perform the multifunctional capacity of materials, emerging as an effective alternative with potential application in wastewater treatment.