A lignin-based carbonized electrospinning membrane with strong light absorption and hierarchical superhydrophilicity for seawater desalination

The high-value utilization of lignin meets the demand for the reclamation of wastes and is of great significance for achieving carbon neutrality. However, lignin is unstable and prone to melting and deformation at high temperatures, requiring a long period of stabilization. The carbon nanofiber (CNF) membrane prepared by electrospinning has advantages such as high aspect ratio, low density, good light absorption, and a large number of pores favorable for steam transportation. Based on co-electrospinning, a lignin-based CNF membrane material was prepared in this work. The preparation process of this material can not only save the stabilization time of lignin-based nanofibers but also improves the hydrophilicity and light absorbance of the membrane through zinc chloride activation and the addition of pore-forming agents (terephthalic acid and polymethyl methacrylate). As a photothermal layer of an interfacial solar evaporation system, the membrane has a light absorption of 94.3% over the whole sun spectrum. Furthermore, the interfacial solar evaporation system with the prepared CNF membrane as the photothermal layer has an evaporation rate of 1.43 kg m−2 h−1 under one sun, with an evaporation efficiency of 93.8%. In addition, the evaporator has good circulation and salt resistance ability. After 15 h of continuous illumination, it still maintains excellent evaporation rate. This type of CNF membrane with lignin as the main carbon source has great potential as a photothermal conversion material in future desalination applications.