Preparation And Modification Of Cornstalk Derived Aterials And Their Photothermal Properties

Solar energy is clean and renewable energy source.The utilization of solar energy has been considered as a way for addressing the serious global problems such as energy crisis and environmental pollution.At present,the lack of freshwater resources has become one of the sever problems facing human society.Solar water evaporation technology is an effective way to solve this problem.The materials used in solar water evaporation technology should have the following characteristics:(1)excellent solar light absorption capacity;(2)good thermal management system,which can minimize heat loss;(3)hydrophilic porous structure for water Transported.We prepared carbonized cornstalks,PB/CS composites and PDA/CS composites as photothermal materials for solar water evaporation,and tested the interface water evaporation performance of the samples.The conclusions are as follows:(1)The light absorb materials for solar driven interface water evaporation were prepare by carbonization of cornstalk which is low in cost and available crop.The carbonized cornstalk has a honeycomb porous structure and good hydrophilic properties,which is beneficial to water transport.It has excellent light absorption capacity in the spectral range of wavelength 250-2500 nm,and its light absorption is up to 90%.Under one solar light intensity,the water vapor generation rate of the carbonized cornstalk is 1.3 Kg m^-2h^-1,the water vapor generation efficiency is 81.4%,and the sample also has excellent stability after conducting multiple interface water evaporation experiments.(2)PB was deposited on the top of cornstalk by a simple ultrasonic method.The prepared PB/CS composite material was used for solar interface water evaporation.The composite material has excellent light absorption ability,and the hydrophilic PB/CS composite material has a porous structure,which is beneficial to water transportation and water vapor overflow.The cornstalk can be used as a heat-insulating matrix material to reduce heat loss and increase the rate of solar water vapor generation.Under one solar light intensity,the water evaporation rate of the PB/CS composite is 1.27 Kg m^-2h^-1,and the steam generation efficiency is about 80.8%.After several experiments of interface water evaporation,the sample still has good stability.The research shows that this composite material has application prospect in solar interface water evaporation.(3)The cornstalk is used as a matrix material,and the PDA is used as the light absorb material.The PDA is deposited on top of the cornstalk to manufacture the PDA/CS composite material.PDA has excellent light absorption performance,which can effectively convert solar energy into thermal energy.The cornstalk at the bottom has low thermal conductivity,which can reduce heat loss,and has a porous structure and excellent hydrophilic properties,which is beneficial to water transportation and water vapor escape.The PDA/CS composite material has excellent solar water evaporation performance for solar interface water evaporation.Under one sun illumination,the water evaporation rate of the PDA/CS composite material is 1.23 Kg m^-2h^-1and the solar steam generation efficiency is 79.1%.After several experiments of interface water evaporation,the sample still has excellent stability.