Superhydrophobic poly(lactic acid) membrane prepared with the induction of modified carbon dots for efficient separation of water-in-oil emulsions

Superhydrophobic separation membranes are considered to be one of the most promising technologies for oil-water separation. However, the plastic waste generated from discarded membranes poses a challenge to the preparation of degraded superhydrophobic separation membranes for achieving eco-friendly separation. In this study, superhydrophobic poly(lactic acid) (PLA) membranes were fabricated using a non-solvent induced phase separation method assisted by l-cysteine modified carbon dots (Cys-CDs). The synergistic effect of Cys-CDs-induced crystallization behavior of PLA and the phase separation process results in the evolution of the surface of the PLA-based membrane from a pistil-like structure to a multi-level micro-nano structure composed of dense lamellar nanofibers and microspheres with an increase in Cys-CDs content. At a Cys-CDs content of 5 wt%, the surface roughness of PLA-based separation membrane reached its maximum, and the water contact angle was as high as 159°. Remarkably, the superhydrophobic Cys-CDs/PLA membrane exhibited promising performance in the separation of water-in-oil emulsions, with a rejection rate of 99.98 % and a flux of 315.74 L·m