Research progress on salt removal from surface of fiber-based interfacial photothermal evaporators
Significance Solar interfacial photothermal evaporation technology possesses the characteristics of high energy conversion efficiency,clean and zero-pollution,which has broad development prospects in the field of seawater desalination and concentrated salt wastewater treatment.However,the salt precipitation caused by the rapid water escape in the process of interfacial evaporation will inhibit the absorption of light and block the vapor overflow channel,which will inevitably reduce the vapor generation rate and the service life of the evaporation device.Fiber materials are one of the ideal materials for designing solar interfacial evaporator surface desalination because of their flexible mechanical strength,low cost,versatility,cutability and processability.Progress This review covers a variety of studies on photothermal evaporation desalination at fiber-based interfaces and focuses on six desalination strategies based on the characteristics of fiber materials,which are grouped into two categories:active and passive.Washing desalination utilizes the water-washing resistance of fiber materials,the surface salt crystals are easily removed by external rubbing.In order to overcome the above-mentioned possible environmental problems,the regional crystalline salt collection strategy not only removes crystalline salt by simple stripping,but also obtains salt as a by-product and reduces the burden on water bodies.However,active desalination strategies still require external forces to remove surface salt crystals,and the sustainability and simplicity of the evaporator are significantly diminished.Therefore,research has exploited the lightness of fiber materials to produce,a easy-to-flip self-cleaning design,when its gravity changes.The current mainstream research focuses on rejecting salt production at the source.The convection effect takes advantage of the loose and porous nature of the fiber material to prepare highly hydrophilic evaporator to achieve a continuous water supply to satisfy salt ion convection.In addition,directional fluid transport with the aid of external forces can move salt ions to low concentrations,while reducing the effect of gravity on salt ion transport.Since the fiber material is easy for surface modification,it is convenient to prepare the Janus structure with the hydrophobic upper layer and hydrophilic lower layer,which can prevent salt ions from reaching the evaporator surface through water,which avoiding salt crystallization.Finally,this paper analyzes the research progress of fiber for surface desalination of interfacial photothermal evaporators,summarizes the problems confronted in the research,and prospects the new development orientation of fiber-based evaporation devices in the future.Conclusion and Prospect Fiber-based evaporation devices generally provide promising development applications for solar interface evaporation and desalination designs because of their high evaporation efficiency,sustained treatment of highly concentrated salt solutions,excellent stability and recyclability,and applicability to long-term desalination work.However,the evaporation rate of fiber-based evaporators still needs to be improved when treating saturated brine.In addition,there are still limitations such as easy clogging and difficult removal when treating other contaminants in the bulk water.In conclusion,fiber-based evaporation devices are still immature and full of technical difficulties and multiple challenges.This paper presents some suggestions from the following aspects:1)to enhance the exploration of multifunctional composite fibers for more application potential in desalination,power generation,sterilization,and impurity removal;and 2)utilizing modern textile technology to design new fibers such as multifunctional hollow fibers,core-sheath structure fibers,shaped fibers,and three-dimensional knitted/woven fabrics to obtain special functions and enhance the vapor generation rate.
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