Rapid developments in the electric industry have promoted an increasing demand for lithium resources. Lithium in salt lake brines has emerged as the main source for industrial lithium extraction, owing to its low cost and extensive reserves. The effective separation of Mg 2? and Li ? is critical to achieving high recovery efficiency and purity of the final lithium product. This paper summarizes Mg 2? /Li ? separation materials and methods in the field of lithium recovery from salt lake brines. The review begins with an introduction to the global distribution and demand for lithium resources, followed by a description of the materials used in various separation techniques, including precipitation, adsorption, solvent extraction, nanofiltration membrane, electrodialysis, and electrochemical methods. A comparison, analysis, and outlook of such methods are comprehensively discussed in terms of principles, mechanisms, synthesis/operation, development, and industrial applications. We conclude with a presentation of challenges and insights into the future directions of lithium extraction from salt lake brines. A combination of the advantages of various materials is the most logical step toward developing novel methods for extracting lithium from brines with high separation selectivity, stability, low cost, and environmentally friendly characteristics.
The epoxidized styrene–butadiene–styrene nanofibers, which were prepared by epoxidation of the styrene–butadiene–styrene in toluene with peroxyformic acid generated in situ, were successfully embedded with nanometer titania dioxide by electrospinning. The optimum blended electrospinning parameters on preparing the nanometer titania dioxide/epoxidized styrene–butadiene–styrene fibers were obtained. The morphology and antiultraviolet property of nanometer titania dioxide/epoxidized styrene–butadiene–styrene composite fiber were examined using scanning electron microscope and an antiultraviolet transmission tester according to American Association of Textile Chemists and Colorists (AATCC183-2004) standard. The scanning electron microscope results showed that nanometer titania dioxide and the epoxy group could lead to the cementation of electrospinning fibers. The ultraviolet protection factor of rutile nanometer titania dioxide/epoxidized styrene–butadiene–styrene fiber membrane is the largest one of the four fiber membranes. The epoxidized styrene–butadiene–styrene nanofibers embedded with nanometer titania dioxide have great potential in the applications of antiultraviolet textiles.
In order to utilize the adsorption selectivity of calixarenes towards heavy metal ions, calixarene functionalized polyimide (Calix-PI) fibers were prepared by three main synthesis procedures including preparation of the calixarene polyamide acid (Calix-PAA) spinning solution via amidation, fabrication of the Calix-PAA fibers by electrospinning, and preparation of the Calix-PI fibers via thermal imidization on the Calix-PAA fibers. The Calix-PI fibers were characterized by Fourier transform infrared spectroscopy, scanning electronic microscopy and thermogravimetric analysis. The Calix-PI fibers display selective adsorption on Pb(II), which is fit with the pseudo-second-order adsorption kinetics model and the Freundlich adsorption isothermal model. The rate constant of the pseudo-second-order adsorption kinetics model and the maximum Pb(II) uptake have all been calculated. The practical adsorption of Pb(II) on the Calix-PI fibers is mainly attributed to the monolayer chemical adsorption and slightly depended on the physical adsorption.
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