Preparation Of Photothermal Hydrogel And Its Application In Solar Seawater Desalination

With the development of society,the demand for water resources continue to increase,which lead to a serious shortage of water resources.The ecosystem deteriorated,which seriously affects the basic life of mankind.In order to solve this problem,researchers use clean e solar energy as a photothermal drive,and use photothermal materials to desalinate seawater as well.Compared with traditional seawater desalination technology,solar seawater desalination technology has the advantages of environmental protection,energy conservation and low cost.Therefore,this paper designs and prepares the photothermal conversion hydrogel with a porous network structure and applies it to seawater desalination.This paper is divided into four chapters.Chapter?,Introduction.Chapter?,The preparation of the MXene-based corn starch/sodium alginate composite hydrogel and the study of its photothermal properties.Chapter?,The preparation and Photothermal performance research of the PVA-based double-layer photothermal gel.Chapter?,The preparation and photothermal performance research of double-layer hydrogel based on magnetic nanoparticles.Chapter?:Introduction.The background of seawater desalination,traditional seawater desalination technology and solar technology are briefly introduced.This paper focuses on the concept and application of photothermal materials and hydrogels.Chapter?:The preparation of the MXene-based corn starch/sodium alginate composite hydrogel and the study of its photothermal properties.Using MXene and calcium chloride as the photothermal material and cross-linking agent respectively,the photothermal hydrogel with a three-dimensional network structurewas prepared doping with physically cross-linked sodium alginate and corn starch.The morphology and structure of the hydrogel were analyzed by scanning electron microscopy and ultraviolet-visible-near infrared spectrum.At the same time,a xenon lamp solar simulator was used to test the evaporation performance,seawater desalination performance and stability of the hydrogel.The results showed that the hydrogel has good light-to-heat conversion and desalination properties,which can be used for long-term seawater desalination.Chapter?:The preparation and Photothermal performance research of the PVA-based double-layer photothermal gel.Using PVA,cationic ionic liquid and ammonium persulfate as the hydrogel substrate,the salt-resistant material and initiator respectively,the hydrogel of water-absorbing layer was formed.The dopamine is polymerized to polydopamine under alkaline conditions,then it is mixed with polyvinyl alcohol and light-absorbing MXene and poured into the prepared water-absorbing layer for freezing and crosslinking.The hydroxyl group of the polyvinyl alcohol in the hydrophilic layer can cross-link with the hydroxyl and amino groups of polydopamine and polyvinyl alcohol through hydrogen bonding,therefore,two layers can be closely connected to form a double-layer hydrogel.This hyudrogel was used as a solar evaporator for exploration.The ultraviolet-visible near-infrared spectrometer,scanning electron microscope,contact angle measuring instrument and other instruments were used to characterize the evaporation material.The evaporation performance,salt resistance and desalination performance of the solar evaporator were tested under the irradiation of the Xenon lamp solar simulator.The results show that the hydrogel evaporator has good light-to-heat conversion performance due to the synergistic light absorption of polydopamine and MXene.Chapter?:The preparation and photothermal performance research of double-layer hydrogel based on magnetic nanoparticles.On the basis of chapter?,the hydrogel evaporator was improved.In this chapter,Fe₃O₄ was cross linked with monomer Sodium styrene sulfonate,N-isopropylacrylamide in cetyltrimethylammonium bromide micelle solution through free radical polymerization reaction to form a hydrogel.Due to the influence of magnetic force and gravity,Fe₃O₄ nanoparticles are uniformly deposited on one side of the hydrogel to form a double-layer hydrogel structure with the upper layer absorbing light and the lower layer absorbing water.It not only saves the absorbent material,but also enhances the absorbent performance.Finally,UV-Vis NIR spectrometer,scanning electron microscope,contact Angle measuring instrument,UV-Vis NIR instrument and other instruments were used to characterize the evaporative materials.Under the irradiation of the xenon lamp solar simulator,the evaporative performance,salt resistance and desalination performance of the hydrogel evaporator were tested.The results show that hydrogels have good salt tolerance and stability,and have great potential in solving water shortage.