Marangoni Effect-Enhanced Iron–Tannin Modified Collagen–Based Evaporator for High-Performance Solar Desalination

Solar-driven interfacial evaporation is a promising strategy for alleviating freshwater scarcity and water pollution. However, developing efficient evaporators using eco-friendly, renewable biomass remains a significant challenge. Herein, we report a bio-derived solar-driven interfacial evaporator (CSIE) based on iron–tannin modified collagen, further enhanced via mechanical micro-perforations to induce the Marangoni effect (EN-CSIE). The influence of pore size and open-area ratio on the Marangoni-driven flow was systematically investigated. The optimized EN-CSIE (with 1.2 mm pore size and 6.1% open-area ratio) achieved a superior evaporation rate of 2.5 kg m−2 h−1 with an energy conversion efficiency of 93.5% under 1 sun illumination. Furthermore, the system demonstrated exceptional purification capabilities, removing over 99.9% of metal ions and organic impurities. Long-term durability tests in 3.5 wt% saline water confirmed a stable evaporation rate of 2.3 kg m−2 h−1 over 15 continuous cycles. This low-cost and sustainable collagen-based evaporator presents a robust solution for solar-powered water desalination, particularly for decentralized clean water production in sun-rich regions.