Attapulgite-based nanofiber membrane with oriented channels for high-efficiency oil-water separation

Nanofiber membranes are distinguished for their high porosity and interconnected pore structures. However, their separation application and performances are affected by irregular pore structures which are formed by the randomly packing of nanofibers. Herein, we report a facile approach to produce nanofiber membranes with oriented channels, narrow pore size, and low tortuosity. The membranes show a bi-layered structure where magnetic attapulgite (mATP) nanofiber layers are directly supported on macroporous Al₂O₃ substrates. The mATP layers are prepared by drop-coating suspensions on top of the substrates pre-filled with water, and the ordered pore structures are formed at the presence of a magnetic field. Compared with the unordered membranes, average pore size of the ordered membranes reduces from 0.45 to 0.28 μm, with the water permeance increase from 1007 to 1121 L m⁻² h⁻¹·bar⁻¹. Moreover, the stationary flux of ordered membranes increase by 59% with the retention to oil-in-water emulsion increase from 98.7% to 99.2%. Analysis of membrane fouling using the Hermia model shows that the ordered membrane can reduce membrane blocking and thus facilitate membrane cleaning and restore of separation performance.