Study On The Preparation And Photothermal Conversion Properties Of Solar Interface Evaporation Materials

With the rapid growth of global population and the increasingly serious problem of water pollution,the shortage of water resources has become a major obstacle to human health,economic and social sustainable development.In recent years,solar steam generation based on sunlight has become an efficient,green and recyclable method to purify water resources and alleviate freshwater crisis.The research and development of photothermal materials,which is the core of solar steam generator,has also become a research hotspot in this field.However,the as-known photothermal materials are still limited to be promoted on a large scale and commercialized because of the complex preparation process and the need to improve the photothermal conversion efficiency.In order to solve the above problems,two novel photothermal materials were prepared from recycled cigarette filter heads and commercial cellulose,and their photothermal conversion properties were systematically studied.The specific research contents and conclusions are as follows:（1）In the second chapter,the recycled cigarette filter head was assembled as the substrate material（CF）by physical means,and the reduced graphene oxide（r GO）was used to modify its surface to improve the light absorption capacity.Therefore,CF based photothermal conversion material（r GO-CF）was prepared for solar evaporation.The substrate material CF has intrinsic superhydrophilicity and vertical arrangement structure,low thermal conductivity(0.0733 W m^-1 K^-1),sufficient water transmission and good thermal insulation performance in the process of photothermal evaporation.After the surface modification of r GO,r GO-CF shows nearly 100%strong absorption capacity（250 nm-2500 nm）to sunlight.The results show that the evaporation rate of r GO-CF under 1 k W m^-2 simulated sunlight is 1.623 kg m^-2 h^-1,which is 7.1 times of pure water evaporation rate,and the energy conversion efficiency reaches 94%.In addition,r GO-CF showed good cycle stability.After 10 cycles,the evaporation rate and energy conversion efficiency did not decrease significantly,and the microstructure did not change.The work in this chapter can not only provide a new type of photothermal material for solar steam generation,but also realize the recycling of cigarette filter head and reduce environmental pollution.（2）in the third chapter,the porous cellulose aerogel（A-F）was prepared by multiple freezing and thawing methods using commercial straw cellulose as raw material.Then,the cellulose/silver phosphate composite aerogel（AP-F）was prepared by in-situ polymerization of A-F on the A-F substrate.A-F has good hydrophilicity,macroporous structure and low thermal conductivity(0.090773 W m^-1 K^-1).The photothermal evaporation process can ensure sufficient water transmission and good thermal insulation performance.After silver phosphate modification,the absorption of ap-f to sunlight can reach 95%.Under the simulated sunlight of 1 k W m^-2,the evaporation rate of AP-F is 1.5588 kg m^-2 h^-1,and the evaporation efficiency is 95.74%,which is higher than that of A-F.In addition,AP-F can be applied to the treatment of dye wastewater due to its good photocatalytic activity.With Rhodamine B,methylene blue and methyl orange as the target pollutants,AP-F can degrade the target pollutants at the same time of interface evaporation.The evaporation rates of AP-F in 5 mg L^-1rhodamine B,methylene blue and methyl orange solutions were 1.3824 kg m^-2 h^-1,1.3440 kg m^-2 h^-1 and 1.3344 kg m^-2 h^-11,respectively.The photothermal conversion efficiencies were 84.12%,80.97%and 80.31%,respectively.High evaporation rate and energy conversion efficiency can be achieved,and the dye solution can be degraded by photocatalysis at the same time.