Preparation Of Chitosan-based Superwetting Materials And Their Photothermal Water Purification Performance

In recent years,solar-driven evaporation has attracted enormous research interest due to its low-cost and sustainable potential.In the process of producing fresh water,solar interface evaporators face complex water source environments.Water bodies such as seawater and industrial sewage also contain inorganic salts and oil pollution.These substances can easily block the water transmission channels of photothermal materials,resulting in a decrease in photothermal conversion efficiency.Consequently,when using light-to-heat conversion materials for freshwater production,they need to have high stability and oleophobic properties to adapt to the harsh water source environment.Therefore,this study mainly prepares chitosan-based superwetting materials through reasonable design,and uses its superhydrophilic/underwater superoleophobic properties to study the separation performance of oil/water mixtures,underwater anti-oil pollution performance,and enhance the anti-pollution of solar evaporators.For multi-scenario applications,give solar evaporators more performance,explore and test additional performance.The main research contents and conclusions of the paper are as follows:（1）A composite hydrogel was prepared through freeze-thaw treatment,using chitosan,polyvinyl alcohol,and carbon black as raw materials.The obtained hydrogel displayed both slippery oil-repellency and water-affinity in air,underwater,when submerged in oil,and exploiting this special wettability,the hydrogel coated mesh can be used to separate oil/water mixtures efficiently.After 25 oil-water separation cycles,the hydrogel-coated filter still had a separation efficiency of over 98%.With its superhydrophilicity and active functional groups,the resulting hydrogel was able to absorb dye molecules dissolved in water effectively.Due to the photothermal effect of carbon black,the local temperature of the hydrogel was increasing quickly under sunlight illustration,which allowed it to be an advanced platform for daily wastewater purification through solar distillation.（2）Inspired by the characteristic structure of conifers,we developed a 3D chitosan reduced graphene oxide/polypyrrole aerogel evaporator with vertically and radially aligned structures through a directional freezing process.The radially porous walls and vertically arranged channels within the 3D aerogel were able to facilitate high light absorption,localizing converted heat,rapid water transport,and self-salt discharge.Under 1 sun irradiation,the aerogel vaporizer displayed an improved light absorption characteristic of95%and high-rate evaporation(～3.19 kg m^-2 h^-1)achieved continuous freshwater from the saturated brine production without solid salt crystallization.Besides achieving seawater desalination,the obtained aerogel could purify organic wastewater and emulsions through solar distillation with high-rate continuous water production.