| Water is the source of life for human survival and development.The survival and development of human society are inseparable from water resources.Our country has a large population,but the total fresh water resource is small,is one of the most deficient countries in the world water resource.With population growth,climate change and water pollution,the shortage of fresh water resources is becoming more and more serious,which seriously threatens the sustainable development of modern society.In order to effectively alleviate the shortage of fresh water resources,a variety of desalination technologies including ion exchange method,reverse osmosis membrane method,electrodialysis method and distillation method have been widely studied.However,these desalination technologies are usually accompanied by huge energy consumption,which seriously hinders their large-scale application.In recent years,with the in-depth research of solar evaporation technology and the vigorous development of photothermal conversion materials in the field of energy,researchers have proposed a new solar driven interfacial evaporation（ISSG）technology.This technology directly locates the energy generated by solar irradiation at the thin layer of air-water interface on the upper surface of the photothermal material.Compared with the traditional evaporation technology,it minimizes the energy loss and effectively improves the photothermal conversion efficiency.After recent years of exploration,the research of solar-driven interfacial evaporation system has developed rapidly.A variety of solar-driven interfacial photothermal evaporation systems using metal nanomaterials,semiconductor materials,carbon-based materials and organic polymer materials as photothermal conversion materials have been reported.However,from the development trend of solar interfacial evaporation system,it is still the focus of research to further improve the salt resistance of the interfacial evaporation system and expand the application of the interfacial evaporation system.Because the solar-driven interfacial evaporator is prone to salt precipitation,oil stain accumulation and dye enrichment in high-concentration brine,oil-water or organic pollution wastewater,it will seriously block the pore of the material,affect its sunlight absorption capacity and water molecule transmission,and reduce the evaporation efficiency and service life of the interfacial evaporation system.Therefore,it is of great significance to improve the salt resistance and pollution resistance of evaporation system through reasonable design.Based on this,this paper intends to take advantage of the repulsive effect of ionic groups in ionic liquid on ions in salt solution,use ionic liquid grafting materials or polyionic liquid spraying methods to improve the salt-resistance performance of the interface evaporation system,and improve its anti-fouling performance by hydrophilic and oleophobic modification of the surface of the interface evaporation system.The photothermal conversion efficiency and salt-resistant and pollution-resistant properties of the prepared materials were tested.The main factors affecting the photothermal conversion efficiency and the mechanism of salt-resistant and pollution-resistant interface evaporation system of ionic liquid were discussed.The main contents and conclusions of this paper are as follows:（1）1-allyl-3-methylimidazole hexafluorphosphate was the monomer,copper bromide was the catalyst,pretreated silica（Si O2-Cl）was the support,and azodiisobutyronitrile was the initiator.N,N-dimethylformamide was used as solvent to prepare ionic liquid grafted Si O2（Si O2-PILs）by atom transfer radical polymerization（ATRP）.Hydrogels were prepared by gelatinization with starch doping,and Si O2-PILs/starch was prepared in situ by spraying on the surface.The porosity of Si O2-PILs/starch is 60.56%,the total pore area is 0.195 m2g-1,the thermal conductivity is 0.411W m-1K-1in wet state,the light absorption rate of the black upper surface is 91%,showing good hydrophilicity and resilience.Large pore structure based on Si O2-PILs/starch,low thermal conductivity,excellent light absorption and good water transport capacity.Under the test condition of simulating one solar intensity(1 k W m-2),the photothermal conversion efficiency of Si O2-PILs/starch as solar-driven interface evaporator is 91.72%.It also showed excellent long-term salt resistance to 20 wt%Na Cl solution and good purification effect on wastewater containing organic dyes and bacteria.（2）Poly（ionic liquid）s（PILs）with excellent antibacterial properties was prepared by free radical polymerization with 1-vinyl-3-hexylimidazole tetrafluoroborate as monomer,azodiisobutyronitrile as initiator and N,n-dimethylformamide as solvent.Ethyl cellulose microspheres（ECM）were prepared using ethyl cellulose（EC）as raw material by solvent volatilization method.Sodium alginate（SA）and ECM were mixed with Ca2+solution as crosslinking agent,and ethyl cellulose microspheres aerogel（ECM-PILs）with aligned pore structure were prepared by directional freezing.Polypyrrole（PPy）was synthesized by in-situ polymerization on the outer surface of aerogel.Finally,PPy-ECM-PILs was prepared by spraying PILs on the bottom and side.With good hydrophilicity,strong solar absorption（about 98%）,low wet thermal conductivity(0.2064 W m-1K-1)and low apparent density(0.31 g cm-3),the evaporation rate of PPy-ECM-PILs in pure water is as high as 1.603 kg m-2h-1.It corresponds to a good photothermal conversion efficiency of 90.86%at 1 k W m-2solar illumination intensity.Thanks to the vertically aligned channels of PPy-ECM-PILs,it showed good salt tolerance even in high concentrations of brine（evaporation efficiency was 78.78%in 20 wt%Na Cl solution）.In addition,PPy-ECM-PILs has good antibacterial properties.（3）1-vinyl-3-butylimidazole bromide was used as monomer,N,N’-carbonyl diimidazole was used as bonding agent,azodiisobutyronitrile was used as initiator,deinked newspaper waste（DNP）was used as carrier material,and dimethyl sulfoxide（DMSO）was used as solvent.In order to increase its applicability and stability in waste newspaper aerogels（INPs）,the surface and side surfaces of the aerogels were sprayed with hydrophilic and oleophobic polymer PDDA-PFO/Si O2,and a solar energy evaporator（OR-INP）with good salt-and oleophobic properties was prepared.OR-INP benefits from extensive solar absorption（about 92%）in wet state,low thermal conductivity(0.1108 W m-1K-1),strong water transport capacity,strong hydrophilic and oleophobic properties.At 1 k W m-2solar light intensity,The solar evaporation efficiency of pure water,20 wt%Na Cl and 5 wt%oil-containing wastewater is up to 93.25%,84.96%and 78.46%,respectively.In addition,aerogel still has a good purifying effect on the solution containing organic dyes,heavy metal ions or bacteria. |
