Preparation Of Carbon Matrix Composites And Its Solar Interface Water Evaporation Performance

With the rapid growth of the population and the acceleration of the industrialization process,the shortage of freshwater resources has become the biggest obstacle to human development.To alleviate this serious problem,many seawater desalination technologies have been developed and applied in practical production.However,remote islands and ports are not compatible with some energy-intensive and complex seawater desalination technologies.Solar-driven interfacial water evaporation is a green,sustainable,clean and pollution-free technology.Its main principle is to use photothermal materials to absorb light energy and convert it into thermal energy,to locally heat the water and vaporize the water to achieve desalination.Therefore,excellent light absorption,good thermal management,and sufficient water supply are the key factors in preparing efficient solar evaporators.In this context,this paper is based on carbon-based materials with wide-spectrum absorption and strong photothermal conversion,combined with bamboo shoots with low thermal conductivity and superhydrophilic characteristics to construct a hierarchical solar evaporator.On the basis of biomass porous carbon,silver nanoparticles were introduced by in-situ thermal reduction strategy to enhance the photothermal conversion performance and durability of the evaporator.Finally,the interfacial evaporation system was simplified,and multi-physical field coupling analysis was carried out using COMSOL Multiphysics to verify the feasibility of the model by comparative analysis.The main research contents are as follows:（1）In this thesis,bamboo shoots are used as raw materials,the method of high temperature carbonization is used to prepare bamboo shoots porous carbon（BSC）as photothermal conversion material,the method of freeze drying is used to prepare bamboo shoots porous substrate,and the biomass porous carbon-bamboo shoots solar evaporator（C-BS solar evaporator）is prepared by coating.The exposure of BSC particles on the surface of the porous bamboo shoots and the directional channels of the porous bamboo shoots ensure efficient light absorption and rapid water transport.The light absorption rate of the C-BS solar evaporator reaches 94%.Under one solar light intensity,the evaporation efficiency of C-BS solar evaporator reaches 1.32 kg m^-2 h^-1,and the photothermal conversion efficiency reaches 74.3%.In the real seawater evaporation test,the main ion removal rate reaches 99.99%.（2）On the basis of biomass porous carbon,silver nanoparticles doped porous carbon bamboo shoot（Ag-BSC）was prepared as photothermal material by high temperature pyrolysis reduction strategy,and silver nanoparticles doped porous carbon bamboo shoot solar evaporator（AC-BS solar evaporator）was prepared by simple coating.The Ag NPs can enhance the light absorption capacity and photothermal conversion efficiency of AC-BS solar evaporator at the same time,which shows a high light absorption rate of 96%.Under one solar illumination intensity,AC-BS solar evaporator achieves the evaporation efficiency of 1.51 kg m^-1h^-1,and the corresponding photothermal conversion efficiency is86.8%,1.17 times that of C-BS solar evaporator,and maintains stable evaporation efficiency in acidic,alkaline,organic solutions and seawater.The removal rate of main ions in seawater reaches 99.99%.In addition,AC-BS solar evaporator also has self-cleaning and antibacterial properties,which facilitates its efficient use in practical applications.（3）The interfacial evaporation system was simplified,and the traditional macroscopic heat and mass transfer model was established based on COMSOL Multiphysics.The coupling effect between the velocity field,vapor concentration field,temperature field and relative humidity field of the whole interfacial evaporation system was analyzed numerically.The results show that the interface temperature trend is basically consistent with the experimental results,and the error between evaporation efficiency and experimental results is less than 5%,which proves the feasibility of macroscopic heat transfer model.