Magnetic graphene oxide functionalized with crystalline nanocellulose and zwitterionic polymers to achieve UF nanocomposite membranes of advanced performance

Inevitable tendency to bio-fouling is one of the main challenges restricting the application of ultrafiltration membranes in wastewater treatment. To address this challenge, herein, by functionalizing the synthesized magnetic-graphene oxide with crystalline nanocellulose and zwitterionic polymers, a novel nanocomposite was introduced, fully characterized, and incorporated into the matrix of PSf membranes to manipulate their water permeability/selectivity and fouling/biofouling resistances. Based on the obtained results, such nanofiller was able to provide the membranes with more hydrophilic surface of less roughness, and thereby, enhanced pure water flux, flux recovery ratio, and anti-fouling properties. Under 2 bar pressure, the pure water flux was significantly increased from 61.18 LMH in the pristine membrane to 123.3 LMH in the nanocomposite membrane. Furthermore, the hydration layer formed by the zwitterionic groups on the surface of nanocomposites was able to reduce the adhesion of biomolecules and microorganisms, and thus, provide the membranes with advanced anti-fouling properties. The anti-bacterial studies indicated that, through either anti-adhesion or antimicrobial mechanisms, the prepared nanocomposite membranes possessed more biofouling resistances against Gram-positive/negative bacteria. The experimental results confirmed that 0.05 wt% was the optimum concentration of the nanocomposite. Accordingly, even at such minimal amounts, the introduced nanocomposite was able to considerably tailor the membrane characteristics, resulting in the membranes of high performance and robust fouling resistance.

Automated summary

In this study, a novel nanocomposite was developed by functionalizing the synthesized magnetic-graphene oxide with crystalline nanocellulose and zwitterionic polymers to address the challenges of bio-fouling in ultrafiltration membranes. The nanofiller improved the hydrophilicity and roughness of the membranes, resulting in higher water flux, flux recovery ratio, and anti-fouling properties. The hydration layer formed by the zwitterionic groups on the nanocomposite surface reduced the adhesion of biomolecules and microorganisms, providing advanced anti-fouling properties. The nanocomposite membranes also exhibited improved biofouling resistance against Gram-positive/negative bacteria through anti-adhesion or antimicrobial mechanisms.