| At present,there is a shortage of freshwater resources all over the world.As natural renewable energy,solar energy drives seawater evaporation to be green,energy-saving,simple and efficient.However,many photothermal materials are made by hand,and some artificial compounds or polymer plastics are not environmentally friendly in practical applications.In addition,some photothermal materials and photothermal devices have high costs and complex preparation problems,so it is urgent to find a simple,low-cost and environmentally friendly photothermal material substrate,to enhance the environmental advantages of solar seawater evaporation and lay a foundation for the application of seawater evaporation.Bamboo,as a renewable biological material,has the advantages of directional water transport,low thermal conductivity,can be used as the base of photothermal materials.At the same time,bamboo has the advantages of low price and simple base preparation technology.Therefore,by studying the characteristics of bamboo,it is expected to design bamboo as the base of photothermal materials,compound photothermal materials with bamboo and establish a connection,and realize a large number of efficient seawater evaporation under the condition of solar energy.In this paper,inspired by natural bamboo transpiration,a bamboo-based seawater evaporation device with photothermal material was prepared by using microtubules along the growth direction of natural bamboo as the water transport channel.In order to prove that bamboo is a good base for evaporating water,the study confirmed the hydrophilicity of bamboo through contact angle test,and conducted thermal conductivity test to support the relatively low thermal conductivity of bamboo,and preliminarily calculated the feasibility of bamboo moisture transportation based on microstructure and capillary effect,and analyzed the tolerance stability of bamboo under different environments.Finally,in this study,the suitable thickness of bamboo was used as the base for seawater evaporation.The main research contents of this paper are as follows:(1)With bamboo as the base material,the plasmonic bamboo photothermal conversion material was successfully prepared by depositing nanometer plasmonic particles on the surface of the bamboo microchannel in hot solution.The plasmonic bamboo has a high light absorption intensity in the wavelength range of 250-2500nm,with maximum light absorption of over 99%.At the intensity of 10 Suns,the photothermal conversion efficiency is up to 87%.Besides,the bamboo-based photothermal material has good cycling stability.Under the illumination intensity of 5 Suns,the photothermal material remains stable after 140h of cycling test.After desalination,the concentrations of Na+,Mg2+,Ca2+and K+in the collected freshwater decreased to 3.169mg/L,0.5015mg/L,0.4289mg/L and 0.2754mg/L,respectively,showing significant desalination effect.Due to the biocompatibility of bamboo materials,the stable relationship between plasma metal nanoparticles and the bamboo biological surface has been successfully constructed,thus the bamboo-based photothermal materials constructed have high efficiency of water evaporation and have broad prospects in seawater evaporation and desalination.(2)The ultrasound-prepared GO was deposited on the cross-sectional surface of the bamboo,and the go/bamboo double-layer photothermal conversion material was successfully prepared.Due to its excellent photothermal conversion and cycling stability,GO/bamboo composites have high light absorption intensity in the solar wavelength range.Under the illumination intensity of one sun,the evaporation rate can reach 1.25kg m-2 h-1,and the photothermal conversion efficiency is 79.8%.Under the illumination intensity of 10 Suns,the material temperature can reach 92?,and the photothermal conversion efficiency can reach 88%.The double-layer photothermal material prepared by surface deposition is converted into photothermal graphene oxide in the upper layer,and the natural bamboo material in the lower layer can effectively retain heat.The double-layer design used in the research can effectively utilize the material,which provides a good idea for the structure of the solar water evaporation device.(3)The bamboo was carbonized at high temperature under the argon atmosphere to prepare carbonized bamboo photothermal conversion materials for efficient evaporation of solar water vapor.The black bamboo charcoal calcined at high temperature was directly used as light-absorbing material,and the carbonized bamboo retained its vertical porous structure,so that water could still be transported efficiently.To fully decarbonize bamboo,carbonized bamboo was prepared at different carbonization temperatures(500?,600?,700?,800?,900?).Through pore determination,hydrophilicity,and carbonization degree comparison,it is concluded that carbonized bamboo at 700?has the optimal evaporation performance of seawater,and its evaporation rate is 2.112kg·m-2·h-1 under the illumination intensity of one sun.In general,carbonized bamboo has good optical absorption performance,and its light absorption intensity is higher than 70%and up to 95%in the wavelength range of 250-2500nm.Under the illumination intensity of one sun,the photothermal conversion efficiency of carbonized bamboo is all above 80%.Also,carbonized bamboo has excellent thermal insulation performance.The thermal conductivity of the materials obtained at 500?,700?and 900? is 0.1611,0.1964 and 0.2291W·m-1·k-1,respectively.Thus,under the illumination of seven Suns,the surface temperature of carbonized bamboo at 700? can reach 73? due to local heat concentration.After the desalination with carbonized bamboo,the main ions of Na+,Mg2+,Ca2+ and K+ in the water were 2.11mg/L,0.55mg/L,0.27mg/L and 0.29mg/L,respectively.Carbonized bamboo photothermal materials directly prepared by high-temperature carbonization do not need to add complex,the process complexity is reduced,and it is environmentally friendly.The research provides a way for the development of green photothermal materials and seawater evaporation. |
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