Preparation And Performance Study Of Fabric-Based Solar Steam Evaporation Materials

The scarcity of fresh water resources is an important crisis facing mankind.As a promising technology,solar thermal evaporation has great application potential in wastewater treatment and seawater desalination.The traditional seawater desalination technology has high cost and low efficiency,which is not conducive to the large-scale development of seawater desalination.Solar evaporation seawater desalination uses solar evaporation seawater to collect fresh water,which has the advantages of convenience,green,high efficiency and low cost,and conforms to the concept of sustainable development.Therefore,the development of low-cost and high-efficiency evaporator suitable for large-scale application is a technology worth studying.Carbon based materials show promising heat conversion efficiency due to their broadband solar energy absorption.In this paper,plain cotton fabric（PCF）and grooved cotton fabric（GCF）are modified by spraying carbon nanotubes（CNTs）,and an efficient solar evaporator structure is designed to explore the performance of various modified fabrics in the interface solar energy evaporation.The research is mainly divided into the following four aspects:（1）PCF was modified by spraying CNTs,its morphology and hydrophilicity were investigated,and the influence of the change of spraying layers on the photothermal absorption and water evaporation properties of plain cotton fabric was studied.The modified fabric has good hydrophilicity.The ultraviolet visible near-infrared spectrum test shows that the light absorption rate of the five layer CNTs plain cotton fabric sprayed at 350-2500 nm reaches 94.56%,and the evaporation rate of ionic water and 3.5 wt%Na Cl solution under one solar intensity(1 k W m^-2)is 1.796 and 1.732 kg m^-2 h^-1,respectively.The photo thermal conversion efficiency can reach 86.9%and 81.3%.（2）Through spraying CNTs to modify GCF,the morphology and hydrophilicity of GCF were investigated,and the photothermal absorption and water evaporation properties of sprayed CNTs grooved cotton fabric were investigated by comparing the sprayed CNTs plain fabric;The influence of groove structure on the photothermal absorption and water evaporation of fabrics was investigated.Ultraviolet visible near-infrared spectroscopy of five layers of sprayed CNTs grooved cotton fabric shows that the light absorption rate at 350-2500 nm is 95.72%,and the evaporation rates of deionized water and 3.5 wt%Na Cl solution at a solar intensity(1 k W m^-2)are 1.986 and 1.924 kg m^-2 h^-1,respectively.The photo thermal conversion efficiency can reach 92.3%and 89.6%.The photo thermal absorption performance and water evaporation performance of sprayed grooved fabric are better than those of sprayed plain fabric.（3）To explore the influence of the evaporator structure change on the evaporation rate of the five layer CNTs grooved cotton fabric under one solar intensity(1 k W m^-2).The evaporation rate of deionized water under 1 solar light intensity without evaporator and support column is 0.254 and 1.867kg m^-2 h^-1,which is obviously lower than that with complete evaporator,proving that the design of evaporator effectively improves the water evaporation capacity of fabric.（4）The seawater desalination capacity and outdoor actual evaporation capacity of 5 layer CNTs grooved cotton fabric were investigated.The seawater desalination test proved that the ion concentration of seawater evaporated from the 5-layer CNTs grooved cotton fabric decreased significantly,the ion removal rate reached 99%,and reached the World Health Organization drinking water standard.The actual evaporation test was carried out outdoors.The average evaporation rate of the five layers of CNTs grooved cotton fabric sprayed in 3.5 wt%Na Cl solution could reach 1.43 kg m^-2 h^-1,indicating that the five layers of CNTs grooved cotton fabric sprayed can be used for outdoor actual evaporation.