Repurposing facial tissue waste to construct flexible hierarchical MOF-based photothermal material with lower evaporation enthalpy for high efficient solar-driven seawater desalination and wastewater purification

Facial tissue (FT) waste produced during daily makeup processes is a severe threat to the natural environment when discarded. Herein, an eco-friendly method to reuse FT waste is proposed. Using the cleaned FT waste as substrate, flexible hierarchical MOF-based photothermal material (Ni-CAT@PDA@FT, NPFT) with coral-like bionic structure is prepared for solar driven interfacial water evaporation by in situ surface modification with polydopamine and growing Ni-CAT crystals via the hydrothermal method. Benefiting from the hierarchical structure and synergistic photothermal effect of Ni-CAT and PDA, NPFT achieves 96.41 % (250-2500 nm) light absorption and 93.5 % photothermal conversion efficiency. In addition, NPFT has excellent hydrophilicity, salt resistance, and reduced evaporation enthalpy (decreasing from 2453.3 to 1481.6 J g- 1 ). Therefore, it possesses a great evaporation rate of 2.73 kg m- 2 h-1 under 1 sun (with the tilt angle of 45 degrees). In addition, the photo- degradation capacity of NPFT facilitates high efficient wastewater purification (the pollutant removal efficiency is more than 99 %). This study not only provides new opportunities for sustainable freshwater supply from clean solar energy, but also provides promising solutions to waste repurposing and environmental protection.