Chemically modified activated carbon decorated with MnO₂ nanocomposites for improving lithium adsorption and recovery from aqueous media

Lithium (Li⁺) is considered as promising element in a variety of fields, including medicine, manufacturing, dyes, and the glass industry. Thus, the need for lithium has continued to escalate. Chemically modified activated carbon (CAC) supported with manganese dioxide (MnO₂) nanoparticles was prepared using different manganese salt concentrations (0.1, 0.15, 0.12 and 0.2 M), a facile impregnation approach for enhancing the capacity of activated carbon for Li⁺ adsorption from aqueous media. The structural, morphological, physico-chemical and elemental properties were characterized by FE-SEM, EDAX, FE-TEM, FTIR, XRD, BET and ICP-OES. A batch experiment was performed to optimize the parameters (pH, adsorbent dose, and contact time) for Li⁺ adsorption. A kinetic study indicated that lithium sorption process followed a pseudo-second order reaction. Comparative analysis revealed that adsorption capacity of CAC increased with an increase in manganese loading, CAC-Mn0.1, CAC-Mn0.12, CAC-Mn0.15, and CAC-Mn0.2 with q_e values of 50.1 mg/g, 65.04 mg/g, 69.93 mg/g and 88.5 mg/g respectively. A desorption study was performed to illustrate the benefits of sorbents by using HCl as an eluting agent. The competitive Li⁺ adsorption and reusability property during four adsorption/desorption cycle showed high selective Li⁺ adsorption with regeneration tendency, which enable the synthesized nanocomposites as potential candidature adsorbents for lithium recovery from aqueous solution.