Design And Preparation Of β-Cyclodextrin-Based Photothermal Materials And Its Water Treatment Performance

Solar interfacial evaporation as a new technology to obtain fresh water from seawater or wastewater is of considerable significance to alleviate water shortage.In response to the incomplete types of wastewater treatment by photothermal materials and the problems of water supply and salt crystallization during evaporation,two composite aerogels with three-dimensional porous structure were designed and prepared in this paper.The research focuses on:（i）The twoβ-cyclodextrin-based photothermal materials were prepared from the design perspective of high evaporation rate and excellent salt resistance,and its solar interface evaporation performance and water treatment performance were systematically investigated.（ii）The aerogel with vertically aligned pore structure was designed by directional freeze-drying method to realize the directional water transport and optimize the water supply,transport and salt tolerance performance during the solar interfacial evaporation.The main contents and conclusions of the paper are as follows:（1）β-cyclodextrin（β-CD）,graphene oxide（GO）and anionic polysaccharide sodium alginate（SA）were used as raw materials.Theβ-CD grafted GO was compounded with 2%SA solution by sol-gel method and then freeze-dried to obtain a composite aerogel with three-dimensional porous structure（GO-CD/SA）.The aerogel has a high porosity of 88.07%and has favorable thermal stability and mechanical properties.Based on the excellent light absorption（97.4%）,superhydrophilicity,and well thermal insulation(thermal conductivity of 0.052 W m^-1 K^-1),GO-CD/SA has an evaporation rate of 1.79 kg m^-2 h^-1 under 1 k W m^-2 illumination and promising salt tolerance.In addition,GO-CD/SA has excellent purification ability for simulated seawater,organic dye wastewater and heavy metal ion wastewater.（2）β-CD and the cationic polysaccharide chitosan（CS）were used as raw materials.The aerogel with vertical porous structure（CDP-CS）was prepared by sol-gel method by compounding the hydrothermally synthesized cyclodextrin polymer with 3%CS solution by directional freeze-drying,and then the composite aerogel（PPy-La/Al@CDP-CS）was made by bimetallic modification with polypyrrole surface modification.Based on the vertically aligned pore structure of PPy-La/Al@CDP-CS,high porosity（88.18%）,excellent light absorption（98.15%）,and favorable thermal insulation(thermal conductivity of 0.055 W m^-1 K^-1),PPy-La/Al@CDP-CS exhibited an evaporation rate of 1.85 kg m^-2 h^-1 under 1 k W m^-2 illumination and excellent salt resistance.In addition,PPy-La/Al@CDP-CS has excellent purification performance for simulated seawater and fluorinated wastewater.In summary,in this paper,two composite aerogels with three-dimensional porous structures were designed and prepared by sol-gel method using cyclic oligosaccharideβ-CD,anionic polysaccharide SA and cationic polysaccharide CS as raw materials,which provide new photothermal materials in the field of solar interfacial evaporation and provide new research ideas for treating wastewater by solar interfacial evaporation.