Preparation Of Nanofiber Composite Hygroscopic Hydrogel And Study On Its Solar Driven Atmospheric Water Collection Performance

In recent years,the use of abundant water resources in the atmospheric environment to alleviate the global freshwater crisis has been regarded as a reliable way.Hydrogels have a rich three-dimensional network structure,which can capture and store the atmospheric water in the cross-linked polymer network.With the characteristics of high water absorption,they are widely used in the field of atmospheric water collection.However,the application of hydrogel in the field of atmospheric water harvesting is severely restricted due to the inferior mechanical properties,easy deformation and the slow water transport arising from the permeable water.To this end,in this work,hydrophilic cellulose nanofibers are used as the framework to enhance the mechanical properties of poly(N-isopropylacrylamide)(PNIPAM)hydrogels.And the hygroscopic agent of lithium chloride(LiCl)is introduced through impregnation.The prepared hydrogel(PNIPAM/CNF)not only has good mechanical properties,but also achieves a high water adsorption rate.Then,carbon black nanoparticles are uniformly embedded into the nanofibers by electrospinning to prepare the photothermal layer(PAN/CB),which has high solar energy absorption,efficient solar energy heat conversion and good moisture permeability.Finally,the PAN/CB is combined with the PNIPAM/CNF@LiCl to construct the two-in-one PNIPAM/CNF@LiCl-PAN/CB hydrogel.The excellent photothermal performance of PAN/CB contributes to the desorption of water to complete the collection of atmospheric water.The moisture absorption rate of PNIPAM/CNF@LiCl-PAN/CB hydrogel with porous nanostructures and hydrophilic cellulose nanofibers was increased by 209%compared with that of pure PNIPAM hydrogel at 25℃ and 90%relative humidity.The double-layer nanofiber hydrogel prepared in this work has excellent mechanical properties,high efficiency of water transport and atmospheric water collection rate,which provides a new idea for collecting clean water from the atmosphere.