A low-cost CS/PVA@CNTs composite aerogel solar evaporator for plant-adapted wastewater purification

As a green technology with great development potential, solar-driven interfacial evaporation is considered to be an effective way to alleviate the freshwater crisis and achieve efficient water treatment. However, there are still great challenges in preparing evaporators with efficient evaporation, continuous water supply, and structural stability. In this paper, a low-cost CS/PVA@CNTs composite aerogel solar evaporator was prepared by freeze-drying method. CS and PVA form a stable three-dimensional hydrophilic porous backbone through hydrogen bond interactions, ensuring continuous and efficient water transport. At the same time, the introduction of photothermal CNTs realizes the excellent light absorption capacity and efficient photothermal conversion efficiency of the evaporator. Under the condition of 1 kW·m −2 light condition, the evaporation rate of CPAC-5 samples reached 1.73 kg·m −2 ·h −1 , and the evaporation efficiency was as high as 99.73%. Moreover, beyond its efficient evaporation performance, the CPAC-5 evaporator also exhibits excellent purification capabilities for various industrial pollutants. The experimental results show that the evaporator can effectively purify heavy metal ions (Cu 2+ , Zn 2+ and Co 2+ ), organic dyes (MO, MB) and strong acid and alkaline industrial sewage. It is worth noting that the purified condensate can be used for the germination and growth of soybean and mung bean seeds, which verifies its practical feasibility in agricultural irrigation. This research provides new technical ideas for sustainable water treatment and agricultural irrigation driven by solar energy.