Advances in Membranes Based on PLA and Derivatives for Oil–Water Separation

The continuously growing amount of oily wastewater from industrial, domestic, and natural sources poses a major threat to water sustainability, and thus efficient oil-water separation techniques are of utmost relevance. Membrane separation has been a popular approach due to ease of handling, high performance, and versatility. Among all the membrane materials, polylactic acid (PLA) and its derivatives have been of interest as green materials because of their renewability, biocompatibility, and biodegradability. PLA possesses special merits, including low density, high permeability, and high thermal stability. Despite its advantages, PLA also has some demerits, such as brittleness, low tensile strength, and poor heat resistance. These limitations are addressed by PLA-based membranes that are generally reinforced using fillers, surface modification, and structure optimization methods. This review provides a comprehensive overview of recent developments of PLA and its derivatives for oil-water separation, with an emphasis on membrane design, fabrication methods, and porosity enhancement strategies. Some significant fabrication processes like Thermally Induced Phase Separation (TIPS), Nonsolvent-Induced Phase Separation (NIPS), and Freeze Solidification Phase Separation (FSPS) are elaborately addressed. In addition, the review emphasizes methods to improve porosity, mechanical strength, and fouling resistance while maintaining biodegradability. By reviewing recent progress and remaining challenges, this review outlines the future potential of PLA membranes and aims to inspire more research on green, efficient oil-water separation.