Aligned aerogels with high salt-resistance and anti-biofouling for efficient solar evaporation

Solar-driven interface evaporation (SIE) is considered as a clean and sustainable freshwater supply technology with high energy conversion efficiency. However, biomass based SIE devices are always restricted by poor salt resistance and antibacterial properties for long-term usage in the actual environment. Herein, a SIE device with sustainability and good mechanical strength was fabricated by polypyrrole (PPy) modification of the Ca2+ crosslinked ethyl cellulose microspheres (ECM) based aerogels, and sprayed poly(ionic liquid)s (PILs) on the underside and sides to form salt resistant and antibacterial photothermal materials (PPy-ECM-PILs) for efficient SIE. And the as-prepared PPy-ECM-PILs show good hydrophilicity, strong solar absorption (ca. 98 %) and low thermal conductivity (0.2064 W m- 1 K- 1) in wet state, and low apparent density (0.31 g cm-3), resulting the evaporation rate in pure water is as high as 1.603 kg m- 2 h-1 and corresponding to the good photothermal conversion efficiency of 90.86 % under one sun illumination intensity (1 kW m- 2). In addition, owing to the aligned channels, PPy-ECM-PILs show good salt-resistant performance even in high-concentration brine water (NaCl 20 wt%). Moreover, PPy-ECM-PILs exhibited good antibacterial property, which is more important for biomass based solar-driven interface evaporation. This low cost, eco-friendly and sustainable biomass based evaporator may offer new ideas to the design in practical SIE evaporators, showing potential applications in wastewater treatment and freshwater extraction.