Efficient separation of biological macromolecular proteins by polyethersulfone hollow fiber ultrafiltration membranes modified with Fe₃O₄ nanoparticles-decorated carboxylated graphene oxide nanosheets

The separation of biological macromolecules, e.g., proteins, using ultrafiltration membranes in the biotechnology, food and pharmaceutical industries has gained the significant attention of the research community. In this work, iron oxide nanoparticles-decorated carboxylated graphene oxide nanosheets (Fe₃O₄/cGO nanohybrid) were synthesized and incorporated in polyethersulfone (PES) hollow fiber ultrafiltration membranes (HFMs) and the resulting modified membranes were evaluated for the separation of proteins, namely lysozyme, trypsin, pepsin, human serum albumin, γ-globulin and fibrinogen. The physicochemical properties, mainly mechanical strength, hydrophilicity, porosity, pore size, and surface roughness were found to be favorable for the modified HFMs. These properties helped the composite membranes (HFMs modified with 0.1 wt% Fe₃O₄/cGO nanohybrid) in achieving remarkably high pure water flux (110.0 ± 3.8 L/m² h) and as high as 97.8% flux recovery. PES-Fe₃O₄/cGO composite HFMs showed significantly high rejection of lysozyme (92.9 ± 1.3%), trypsin (94.5 ± 1.1%), pepsin (96.9 ± 1.2%), human serum albumin (99.5 ± 0.5%), human γ-globulin (100%), and human fibrinogen (100%). These composite HFMs also maintained their efficacious rejection performance during the long-term studies. Therefore, the HFMs modified with Fe₃O₄/cGO nanohybrid are the potential membranes for the efficient separation of biomolecules, particularly proteins in the biotechnology, food and pharmaceutical industries.