New Material: New Cellulose Based Solar Thermal Conversion Material

Pulp foam is a new kind of porous material with low cost and environmental protection. It uses pulp fiber as raw material, and uses surfactant to foam in the pulp fiber dispersion at normal temperature and pressure. At the same time, the foam can prevent the fiber liquid phase from flocculating and drying collapse, thus forming a uniform porous structure. After filtering and drying, the foam material is made. In the early stage, scientific researchers developed a new type of pulp foam material (Chem. Eng. J., 2019, 371, 34-42; Carbohydr. Poly., 2022, 278, 118963) that can realize functional customized processing with the help of boron ion crosslinking and the introduction of a proper amount of natural polymers, which has great application prospects in new green packaging, architecture, thermal insulation, sound absorption and other fields. ?

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In order to further improve the water resistance of pulp foam materials, researchers introduced natural rubber as a crosslinking agent, and used a simple surface carbonization process to give carbonized pulp foam materials (CPNR) excellent photothermal conversion effect. The CPNR is composed of a photothermal conversion layer at the top and a pulp foam layer at the bottom, without the need for interfacial bonding or modification. The top photothermal conversion layer has excellent light absorption capacity (93.2%), which can absorb incoming sunlight and convert it into heat through photothermal conversion, thus driving water evaporation. The pulp foam layer at the lower part can conduct and transport water from the bottom to the photothermal conversion layer at the top. At the same time, the porous structure, low thermal conductivity (0.1 W mK-1) and rich hydroxyl structure of CPNR make it have excellent thermal insulation and water absorption properties (9.9 g g-1). The water evaporation rate and efficiency of the CPNR prepared in this study reached 1.6 kg m-2 h-1 and 98.1% respectively under the simulated sunlight intensity. In addition, CPNR has excellent salt self-cleaning and salt accumulation prevention properties, and uses cellulose from a wide range of sources and a simple surface carbonization process, making it cost-effective significantly better than existing photothermal conversion materials. Simulation experiments have confirmed that the new cellulose based photothermal conversion materials can be used as water evaporators, and are expected to be used in seawater desalination, salt/metal ion concentration, sewage treatment and other fields. ?

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Recently, relevant research results were published on ACS App. Mater. Inter. The research work was supported by the National Natural Science Foundation of China, Shandong Natural Science Foundation for Distinguished Young Scholars, Shandong Energy Research Institute and Qingdao City. This work was jointly completed by Qingdao Energy Institute and Canada Lake Capital University. ?