Preparation Of Oriented Carbon Nanotube Coated Fabrics And Its Application In Solar Water Evaporation

Solar photothermal evaporation technology is an efficient and reliable method to obtain fresh water.It has attracted extensive attention in the fields of materials,environment,energy because it is sustainable and environmentally friendly.The research emphasis of solar water evaporation is on the development and design of efficient photothermal conversion materials and the enhancement of solar energy absorption capacity.Carbon nanotubes（CNT）have a high absorption in the wide spectrum of sunlight,and have a good photothermal conversion effect.They can further enhance the light absorption through the micro-nano composite structure,and efficiently realize solar photothermal evaporation.Based on the solution evaporation-induced self-assembly technology,the carbon nanotubes on the fabrics surface can spontaneously formed directional arrangement structure along the fiber direction.By using the superior solar-thermal conversion ability and channels of orientational CNT,the evaporation rate of solar water evaporation is improved.And combined with the cold surface of evaporation device,the flexible efficient solar water evaporation of coated fabrics has been realized.The main contents and conclusions of this topic are as follows:（1）The solution evaporation-induced self-assembly technique was used to realize the spontaneously directional arrangement of CNT along the fiber direction,and the coated fabrics with stable load of CNT was obtained by cross-linking with calcium ions.The dispersion solution of carbon nanotubes and sodium alginate（SA）was characterized.It was proved that the non-covalent bond between CNT and SA was beneficial to the stable dispersion of CNT.The micro-morphology analysis of CNT coated fabrics obtained by evaporation-induced self-assembly proves that CNT are aligned along the fiber direction.Through the washing tests about CNT coated fabrics before and after calcium ion crosslinking,proved that directional CNT coating on the fabrics loaded stably because ion crosslinking.（2）A solar simulator was used to study the solar absorption and photothermal conversion performance of CNT coated fabrics.The influence of different layers of self-assembly CNT and different illumination intensity on the photothermal conversion performance of CNT coated fabrics were explored.The reflectivity and absorptivity of directional CNT coated fabrics were measured by UV-Vis-NIR spectrophotometer in the spectral range of 300-2500 nm.It is proved that directional CNT coated fabrics is an excellent solar absorbent material with low reflectivity and high absorptivity.The changes of surface temperature of CNT-coated fabrics under simulated sunlight irradiation were recorded by infrared thermal camera to explore the influence of self-assembly layers and light intensity.The temperature of CNT coated fabrics immediately increased by 15.0℃after 1 min under 1 sun.The temperature increased to 48.8℃after 10 min,which was 19.0℃higher than that of the uncoated fabrics.It proved that the CNT coated fabrics has excellent photothermal conversion performance.（3）The water evaporation rate and energy utilization efficiency of directional CNT coated fabrics were studied by setting up a water evaporation device with cold evaporation surface.And the seawater desalination and textile dye wastewater purification performances CNT coated fabrics were also analyzed.Firstly,the structural design of solar photovoltaic hot water evaporation device reduced heat loss by using heat insulation materials and interfacial evaporation.In addition,there are some heats were absorbed from the environment through the formation of cold evaporation surface.Combined with directional arrangement of CNT,the water evaporation was enhanced.By calculating and monitoring the quality of water evaporation reduction.,the evaporation rate of water reached 1.51 kg·m^-2·h^-1（under 1 sun）,and the energy utilization efficiency of sunlight-water evaporation reached 83.9%.The simulated seawater and wastewater were treated and purificated by evaporation.The ion concentration before and after desalination were measured by inductively coupled plasma mass spectrometry（ICP-MS）.The results showed that the salt ion concentration after desalination decreased by 3-4 orders of magnitude,which reached the WHO standard for drinking water.The analysis of absorption spectrum before and after the purification of dye solution proved that the fresh water with good quality was obtained after the solar water evaporation purification.