Electrospun CB/PNIPAM@PP micro-nano composite membrane: Synergistic efficient oil-water separation based on temperature sensitivity and photothermal effect

In response to the increasingly severe challenges in oily wastewater treatment, the development of separation materials with both high adsorption capacity and intelligent regulation functions is of critical importance. In this study, a unique “micro-meter substrate-nano-fiber layer” hierarchical structure was successfully fabricated by electrospinning temperature-sensitive poly(N-isopropylacrylamide) (PNIPAM) and photothermal carbon black (CB) onto a polypropylene (PP) nonwoven fabric. This architecture significantly enhanced the capillary effect and oil storage capacity while endowing the material with excellent photothermal response characteristics. Under simulated sunlight, the composite membrane rapidly exceeds the lower critical solution temperature (LCST≈32 °C) of PNIPAM, enabling a fast switch in surface wettability. Experimental results demonstrate that the membrane increases the adsorption rate of high-viscosity crude oil by 3.5 times (reducing adsorption time from 7 min to 2 min) via the photothermal viscosity-reduction effect. Furthermore, the membrane achieves high-efficiency separation for various water-in-oil (W/O) emulsions with efficiencies exceeding 95% (up to 97.8%) and high permeation fluxes (7000–9500 L·m −2 ·h −1 ), while exhibiting a maximum oil adsorption capacity of 34.70 g·g −1 . Notably, the composite membrane maintains robust performance over 10 consecutive cycles, with separation efficiency remaining above 95%. The “photothermal-thermosensitive” synergistic strategy effectively overcomes the limitations of traditional materials in high-viscosity oil treatment and high energy consumption, providing a versatile and durable solution for complex oil-water separation.