Adsorption of Li(I) Ions through New High-Performance Electrospun PAN/Kaolin Nanofibers: A Combined Experimental and Theoretical Calculation

Lithium (Li), as a strategic energy source in the 21st century, has a wide range of application prospects. As the demand for lithium resources grows, refining lithium resources becomes increasingly important. A novel method was proposed to directly prepare polyacrylonitrile-LiCl·2Al(OH)3·nH2O (PAN-Li/Al-LDH) composites from kaolin with simple operation and low cost, showing effective adsorption performance for the removal of Li(I) from brine in a salt lake. Moreover, several techniques have been applied for characterization, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and the Brunauer-Emmett-Teller method. Batch adsorption experiments were conducted to investigate the adsorption behaviors of PAN-Li/Al-LDHs for Li(I) in salt-lake brines, indicating that the adsorption equilibrium could reach within 2 h, and the adsorption kinetics for Li(I) conforms to the pseudo-second-order model. The adsorption isotherms are consistent with those obtained by the Langmuir model, with a maximum adsorption capacity of 5.2 mg/g. The competitive experimental results indicated that PAN-Li/Al-LDHs exhibited specific selectivity for Li(I) in the mixed solutions of Mg(II), Na(I), K(I), and Ca(II) with the selectivity coefficients of 9.57, 19.38, 43.40, and 33.05, respectively. Moreover, the PAN-Li/Al-LDHs could be reused 60 times with basically unchanged adsorption capacity, showing excellent stability and regeneration ability. Therefore, PAN-Li/Al-LDHs would have promising industrial application potential for the adsorption and recovery of Li(I) from salt-lake brines.