Microwave-assisted hydrothermal synthesis of lithium ion-sieve for adsorption of lithium ion in coal gangue leaching solution

A two-step method involving microwave-assisted hydrothermal synthesis and solid-phase calcination was employed to prepare the Li1.6Mn1.6O4 (LMO) precursor. Material characterization demonstrated the structural stability of LMO even after acid pickling, resulting in the creation of the ion-sieve H1.6Mn1.6O4 (HMO) with the most notable Li+ adsorption capacity of 29.45 mg.g(-1). The adsorption isotherm of HMO adhered to the Langmuir isothermal model (R-2 = 0.9929), indicating a smooth and monolayer adsorption process. Simultaneously, the adsorption kinetics of HMO was consistent with the pseudo-second-order kinetic model (R-2 = 0.9911), indicative of chemisorption. Upon undergoing five adsorption-desorption cycles, HMO's adsorption capacity remained above 22.32 mg.g(-1). Evaluation of the distribution coefficient (K-d) and the separation factor (alpha(Li)(Me)) for HMO in both coal gangue leaching solution and simulated salt lake brine highlighted its exceptional selectivity. Notably, HMO achieved a remarkable 99.9% adsorption rate in the coal gangue leaching solution. These outcomes underscore the efficacy of the synthesized HMO in highly selective Li+ recovery from both coal gangue and salt lake brine, additionally emphasizing the potential of coal gangue as a valuable lithium resource with significant prospects for future development and utilization.