Study On The Modification And Photothermal Conversion Of Porous Films Based On Orientation

Solar energy is an inexhaustible and inexhaustible renewable clean energy.The use of solar energy is one of the best ways to solve problems such as energy shortage and environmental pollution.The light-to-heat conversion device is a device that converts solar energy into heat and is used in seawater desalination,sewage treatment,medical disinfection,tumor treatment and other fields.Therefore,the preparation of low-cost and high-efficiency photothermal conversion devices has become a hot spot for scientists to study.In this paper,a three-dimensional light-to-heat conversion device is designed.This device is similar in structure to natural cellulose-based biomaterials,and the interior is composed of micron-level through holes.First,combining the ice template method and the low-temperature phase inversion method,using cellulose as the raw material,a directional porous cellulose membrane with a biomimetic wood layered porous structure was prepared.The prepared cellulose oriented porous membrane has excellent wicking effect and water flux characteristics,and its microstructure is similar to wood.The excellent physical properties of cellulose oriented porous film,including mechanical stability and thermal stability,make it have good application prospects in many fields.When evaluating the performance of solar steam generation,graphene was used to modify the prepared cellulose film.Under the light with an optical power density of 1 k W/m~2,the water evaporation rate of the graphene-modified cellulose oriented porous film was 1.56 kg/m~2h,exceeding the water evaporation rate of pure water and cellulose membrane.The water evaporation rate of the cellulose film is higher than that of the wood solar steam device,and the light-to-heat conversion efficiency is increased from 40.72%to 92.97%.Based on the design of the graphene-modified cellulose oriented porous membrane,it is more difficult for the water to escape from the surface of the cellulose due to the easy formation of hydrogen bonds and ionic bonds between the hydrophilic cellulose and water.Based on this theory,this paper further designs a three-dimensional solar steam generator with high water evaporation rate and good structural stability.The device is a double-layer membrane composed of hydrophobic polyacrylonitrile(PAN)and polyacrylonitrile/graphene oxide(GO).This unique design increases the evaporation rate of water by increasing the absorption of sunlight and the specific surface area.The prepared double-layer membrane has good water wicking performance and flux,and can continuously supply water from the bottom to the top of the solar steam generator.The solar steam generation performance of the device was evaluated by exposing the PAN/GO surface to artificially simulated sunlight with optical power densities of1,5,and 10 k W/m~2.When the optical power density is 1 k W/m~2,the moisture evaporation rate and steam generation efficiency of the PAN/GO double-layer film are 2.27 kg/m~2h and 92.63%,respectively.In order to further improve the photothermal evaporation effect of the polyacrylonitrile/graphene oxide oriented porous double-layer membrane,this paper adjusts the ratio and size of the double-layer membrane to design its shape into the umbrella-like structure of a mushroom in nature,so that the water evaporates at the interface From a flat surface to a curved surface,at the same time,the diameter of the PAN section under the double-layer membrane is reduced to reduce the heat loss under sufficient water supply.Umbrella porous membranes with three angles were prepared,and the effects of angle and ambient temperature on the evaporation effect of light and hot water were explored.When the optical power density is 1 k W/m~2,the water evaporation rate and steam generation efficiency of the polyacrylonitrile/graphene oxide oriented porous double-layer membrane are 2.01 kg/m~2h and90.8%,respectively.