Preparation of solid-solid phase change composites and their solar-interfacial water evaporation performance

Solar powered interfacial evaporation materials are widely used in seawater desalination. But solar energy is intermittent. To solve this problem, researchers combined phase change materials (PCMs) with interfacial evaporation materials. Many PCMs are loaded into the interface evaporation matrix material through physical blending, which may cause leakage problems during long-term use, leading to secondary water pollution. We have developed a novel interfacial evaporation material that continuously and efficiently vaporizes clean water under intermittent sunlight to address these issues. The solid-solid PCMs (BC/PVA/GO-g-LA-SSPCMs) were obtained by chemical grafting of PCMs lauric acid (LA) and graphene oxide (GO), and the substrate material bacterial fibrin (BC) was modified by polyvinyl alcohol (PVA). The material achieved light absorption of 88.8% in the full spectrum range. Under 1 kW m−2 light, the evaporation rate reaches 3.4 kg m−2h−1, and the solar-thermal conversion efficiency is 94.2%. In the dark, the evaporation rate is 1.05 kg m−2h−1, and the solar-thermal conversion efficiency is 49.5%. 15 light-dark cycle experiments and harsh environments (high concentration brine, acidic solution, alkaline solution, dye wastewater) showed high efficiency and stable evaporation performance. The material cost of the evaporator is about 0.98 USD·m−2, and the solar-thermal quality factor is 4.64, which is higher than that of most reported materials. In short, BC/PVA/GO-g-LA-SSPCMs provides a new idea for the future design and development of solar-thermal conversion materials to achieve efficient and continuous saltwater desalination and wastewater purification under intermittent solar-irradiation.