Microwave-assisted acid functionalized carbon nanofibers decorated with Mn doped TNTs nanocomposites: Efficient contenders for lithium adsorption and recovery from aqueous media

The industrial need for lithium metal is foreseen to be stepping up in the near future. Herein, we have successfully fabricated microwave-assisted, acid-functionalized carbon nanofibers (ACNFs) decorated with manganese-doped titanium nanotubes (TNT-Mnx), a novel nanocomposite for Li⁺ adsorption. Nanocomposites (ACNF-TNT-Mn0.5, ACNF-TNT-Mn1, and ACNF-TNT-Mn1.5) were prepared by different strategies: oxidizing acidic treatment, alkaline hydrothermal technique, and a modified conventional Murray approach. The distinctive Li⁺ adsorption parameters were demonstrated: pH (14), nanocomposite dose (0.075 g), and contact time (180 min) by batch adsorption tests. The nanocomposite (ACNF-TNT-Mn1) at optimized adsorption condition was capable of showing Li⁺ adsorption of 52 mg g⁻¹, which is ≈ 10.4 and 4 folds higher than pristine ACNF and TNT-Mnx, respectively. The improved Li⁺ adsorption can be attributed to the combined effect of Mn²⁺ species in TNT-Mnx and large surface area of ACNF within a nanocomposite. The adsorbed Li⁺ ions from nanocomposites were easily recovered (99%). Besides, the nanocomposites show selective Li⁺ adsorption and stability over several adsorption tests. Furthermore, the doping of Mn²⁺ on TNT within nanocomposite leads to the improvement in Li⁺ uptakes. By considering these efficient properties, the fabricated nanocomposites can be applicable on a large scale as a potential adsorbent for Li⁺ recovery.