Fe2O3 nanosheet sacrificed templates for highly-permeable hollow fiber ultrafiltration membranes

Hollow fiber membranes (HFMs) have been widely used in ultrafiltration. However, current HFMs usually exhibit low permeance to ensure satisfactory retention performances. Blending nanomaterials into HFMs matrix can enhance permeance but still can be improved. Herein, we report a facile strategy to fabricate highly-permeable HFMs using inorganic metal oxide nanoparticles as sacrificed templates. Ultrathin Fe2O3 nanosheets are synthesized via hydrothermal method. After blending with minuscule concentrations (0.4 % mass fraction) of the nanosheets, spinning and acid dissolving, HFMs are fabricated with nanosheet-templated channels. These HFMs have enhanced porosity (from 49.7 % to 86.9 %), pore size (from 12.5 nm to 27.5 nm), roughness (from 16.0 nm to 29.3 nm), hydrophilicity (water contact angle from 93.7° to 77.8°), mechanical properties (tensile strength from 3.0 MPa to 4.2 MPa), and antifouling ability (flux recovery ratio from 0.58 to 0.71). The permeance can be increased significantly to 209.2 L m−2 h−1 bar−1, a 10.6-fold improvement compared to the unblended HFMs. The solute rejection of the HFMs is not compromised (e.g., maintaining 10 nm Au at 96.3 % and bovine serum albumin at 86.2 %) due to the small size of templated channels. The sacrificed template blending strategy can be applied to other inorganic metal nanoparticles and various polymer-based HFMs. This work can also provide great inspiration for flexibly designing and conveniently fabricating highly-permeable HFMs in industrial ultrafiltration.