Lignin Microsphere/TiO2 Composite-Based Melamine Sponge with Superhydrophobic and Photothermal Properties for Oil/Water Separation and Anti-Icing

Frequent oil spills and the discharge of oily wastewaters have caused a serious threat to the environment, ecological systems, and the health of human beings. Herein, a durable photothermal and superhydrophobic melamine sponge has been prepared by decorating lignin microspheres (LMs) and TiO₂ nanoparticles via the self-polymerization of dopamine. The superhydrophobic sponge shows excellent chemical stability, thermal stability, mechanical durability, and recyclability. The adsorption capacities of the superhydrophobic sponge for oils and organic solvents range from 22.4 to 84.2 g/g, showing high separation efficiencies larger than 98.6% after 15 cyclic tests. Due to the photothermal effect, the maximum surface temperature of the superhydrophobic sponge reaches 65.2 °C under solar irradiation (1 sun), and the superhydrophobic sponge successfully achieves the ice-free property at a low temperature of −17.8 °C under solar irradiation (0.5 sun). Besides, the LMs@TiO₂ composite coating can be employed on several substrates (i.e., filter paper, carbon cloth, steel mesh, Al sheet, Cu sheet, and NdFeB) to realize surface superhydrophobicity, and exhibits excellent anticorrosion for the coated NdFeB. Therefore, this study proposes a low-cost and multifunctional superhydrophobic MS, opening a new avenue to the rational design of superhydrophobic MS for applications in oil/water separation, anti-icing, and anticorrosion.