Vine utilization strategy: Biomass-based aerogel with vertically aligned channels for highly efficient interfacial solar evaporation

Cellulose aerogel evaporators provide a sustainable strategy to balance energy consumption and freshwater production due to their biocompatibility, renewability, high specific surface area, and large porosity. Inspired by the abundant hierarchal, interconnected water transport channels in luffa vine (LV) that favor efficient evaporation, this study designed an aerogel with vertical channels having micropores on their walls. Fibrillated luffa vine cellulose fibers (LVFB) prepared via mechanochemical methods, retained their original pore structures, and then they were combined with sodium alginate (SA). The aerogel with hierarchical pore structure (LSA-D) was fabricated through directional freeze-drying and calcium ion cross-linking. The natural pore structures of LVFB and the vertical channels in the aerogel led to effective reduction in thermal conductivity (0.055 W⋅m −1 ⋅K −1 ) and enhancement in water absorption rate (17.3 g⋅g −1 ). Moreover, fiber micropores facilitated intercommunication of water and salts among different channels to achieve efficient salt reflux. Next, graphene oxide coating and thermal reduction further improved the light absorption and photothermal conversion efficiency. The final aerogel evaporator exhibited an evaporation rate of up to 2.70 kg⋅m −2 ⋅h −1 under 1-sun illumination, and no salt accumulation was observed during continuous evaporation in brine for 36 h. The aerogel demonstrated significant purification capabilities toward wastewater containing organic dye, heavy metal solutions, and acidic solutions in simulated real-world environments. This study not only enhances the efficient utilization and added value of LV, but also provides innovative design ideas for the structural design of solar evaporator materials, offering significant practical application prospects in addressing the global freshwater crisis.