Multifunctional lignin-mediated biomass hybrid aerogel with plasmon-enhanced solar-driven desalination and sewage purification

Solar-driven interface evaporation is a promising strategy to mitigate the global freshwater shortage. However, low evaporation rate and poor salt tolerance remain the challenges of most evaporators in practical applications. Herein, the chitosan/lignin (CSL) hybrid aerogels were successfully fabricated from chitosan and lignin with opposite charges in an alkaline/urea solvent via eco-friendly crosslinking and facile freeze-drying methods. The presence of lignin in CSL can not only regulate the pore size, improve the hydrophilicity and water transfer ability of aerogel, but also serve as a reducing and stabilizing agent of silver nanoparticles (Ag NPs), and the size of Ag NPs can also be controlled by lignin content. The abundant hydrophilic groups on CSL aerogels can activate water molecules and significantly reduce water evaporation enthalpy by 62 %. The evaporator reveals a syn-ergetic effect of carbon nanoparticles (CNPs) and small-sized Ag NPs with high sunlight-harvesting capability and fast photothermal conversion rate. Thus, the optimal CSL-7:3-C@Ag aerogel evaporator achieves an exceptional evaporation rate of 3.569 kg m- 2 h-1 and photothermal conversion efficiency of 92.05 % under one Sun (1 kW m- 2) illumination. Moreover, the evaporator also exhibits outstanding salt resistance, acid-base stability, and durability, which has a broad prospect in solar desalination and sewage purification.

Automated summary

Solar-driven interface evaporation is a promising strategy to address global freshwater shortage, but low evaporation rate and poor salt tolerance are challenges in practical applications. This study successfully fabricated chitosan/lignin hybrid aerogels with improved properties, such as pore size regulation and enhanced hydrophilicity. The aerogels also demonstrated high sunlight-harvesting capability and fast photothermal conversion rate. The optimal aerogel evaporator achieved exceptional evaporation rate and photothermal efficiency, making it a promising solution for solar desalination and sewage purification.