Hollow-fiber membranes with tunable ultrafiltration performances by continuously depositing bacterial cellulose nanofibers

The fabrication of high-performance hollow-fiber membranes (HFMs) can be effectively achieved through nanomaterial-based surface modification. However, achieving a uniform deposition of nanomaterials onto the curved surface remains a challenge. In this work, we have developed a pressure-driven, liquid-phase continuous deposition method to construct oxidized bacterial cellulose (BC) nanofibers onto HFMs in a layer-by-layer way. By controlling the oxidation time and deposition time, the Immunoglobulin G (IgG) rejection rate increases progressively from 50% to 90.1%, while the water permeance correspondingly decreases from approximately 1500 L m −2  h −1 ·bar −1 to 438.2 L m −2  h −1 ·bar −1 . The introduction of polyethylenimine (PEI) as a property regulator not only strengthens the crosslinking reaction but also further tunes the membrane properties. The oxidized BC membranes achieve a flux recovery ratio (FRR) of 64% in the cyclic filtration tests, which is 4 times that of the pristine substrates. The water permeance of the oxidized BC membranes can still be maintained above 80% of its initial value in the long-term filtration test. Moreover, the consumption of oxidized BC is as low as 1.77 g m −2 for modifying HFMs, which further enhances the process sustainability of HFMs fabrication.