Interfacial Photothermal Evaporation Properties Based On Carbon-based Porous Materials And Their Application In Water Treatment

With the growth of population and industrial development,the global shortage of potable water resources is becoming increasingly serious,and desalination is one of the key strategies to solve the problem.Solar desalination,a new green and sustainable desalination technology,has received widespread attention because of its broad development prospects.Among them,the development of materials with high photothermal conversion performance and the design of evaporation systems with high evaporation performance are the research focuses of this technology.Researchers have designed a variety of high-efficiency interfacial evaporation systems with high evaporation efficiency.However,the preparation process of evaporation units is complicated,the production cost is high,the operation and maintenance are cumbersome,and the evaporation efficiency of evaporation systems needs to be further improved.In order to solve these problems,this paper prepared photothermal conversion materials and constructed a separated interfacial evaporation system using inexpensive and easily accessible natural wood as raw materials,and experimentally investigated the high-performance structure and its evaporation performance.Firstly,carbonized wood（C-W）with surface carbon particle deposition and hollow micro-pore channel structure was prepared by flame carbonization and quenching of mahogany,pine and basswood,and used in seawater desalination experiments.The results showed that the prepared carbonized basswood（C-BW）had higher porosity and better evaporation performance compared with mahogany and pine.The thermal conductivity of C-BW is 0.243 W·m^-1·K^-1,the light absorption at 200-2500 nm is more than 80%,and the stable temperature is 46°C under 1 solar irradiation and 62°C under 3 solar irradiation.10mm C-BW evaporates at a rate of 1.25 kg·m^-2·h^-1for 30 PPT seawater under 1 solar irradiation,and the evaporation efficiency is 78.5%,which is a 198.3%performance improvement compared to 0.419 kg·m^-2·h^-1for natural water.The evaporation rate remained stable when the evaporation experiment was repeated 15 times.The integrated ion removal rate of simulated seawater as well as actual seawater from Bohai Sea,Yellow Sea and South China Sea is up to 99%,and the condensed fresh water complies with GB 5749-2022.To further improve the evaporation efficiency,magnetic carbonized wood（Fe₃O₄-C-BW）was prepared by hydrothermal reaction loaded with Fe₃O₄particles,and evaporation experiments were conducted in an applied magnetic field.The results showed that after loading Fe₃O₄particles,the material exhibited hydrophobic properties,reduced the liquid film vaporization resistance at the evaporation interface,and accelerated the nucleation release rate of water vapor.Fe₃O₄-C-BW had a light absorption of 94%and a stable temperature of 48.3°C under 1 solar irradiation,and the evaporation rate of Fe₃O₄-C-BW with a mass fraction of 0.5%under the action of a 200 m T magnetic field was1.48 kg·m^-2·h^-1,corresponding to an evaporation efficiency of 93.1%,which improved the performance by 254%compared to 0.419 kg·m^-2·h^-1in natural water and 18.4%compared to1.25 kg·m^-2·h^-1in C-BW.Under the action of magnetic field,Fe₃O₄increases the heat flow density of bubbles and reduces the separation diameter of bubbles,which in turn enhances the evaporation efficiency of Fe₃O₄-C-BW.The evaporation rate of Fe₃O₄-C-BW is greater than 1.448 kg·m^-2·h^-1for seawater in the Bohai Sea,Yellow Sea and South China Sea,and the water purification treatment of organic wastewater such as methyl orange,with stable water yield and 100%decolorization rate,and the condensate It meets the secondary drinking water standard.In this paper,based on the design idea of interfacial evaporation system,the separated interfacial evaporation system of biomass carbon material is developed and the magnetic field effect is introduced to improve the water evaporation efficiency,which provides reference and inspiration for the design and preparation of high-performance photothermal evaporator.