Tailored Iron–Polyphenol interfacial networks in bio-based aerogels for solar-driven desalination with life cycle assessment Insights

Tailoring interfacial architectures in porous photothermal materials is critical for advancing solar-driven desalination technologies. Herein, we present a fully bio-based aerogel engineered through an iron-polyphenol coordination strategy inspired by the traditional Chinese “iron-tannin dyeing” method. Liquid-phase tannic acid (TA) extract and solid-phase cellulose from Chinese gallnut were co-assembled with sodium alginate, followed by Fe 3+ /Ca 2+ dual-ion crosslinking and freeze-drying, yielding a TA@SA@Fe 3+ aerogel with hierarchical porosity and adaptive interfacial characteristics. The tailored coordination network enhances light absorption (95.7 %), hydrophilicity, and a high solar evaporation rate of 2.0 kg·m –2 ·h –1 under 1 sun illumination. Its interconnected pores promote salt diffusion, ensuring long-term outdoor operation. Furthermore, the material exhibits strong adhesion on diverse substrates—including melamine sponges and geotextiles—supporting modular integration into scalable desalination systems. A comprehensive life cycle assessment (LCA) confirms the sustainability advantage of this system, with a total emission of only 2.4  kg CO 2 -equivalent per kilogram of material, significantly lower than conventional alternatives. This work offers a green, cost-effective, and application-ready strategy for designing interfacial aerogels, providing a promising platform for next-generation solar-thermal water purification technologies.