Preparation and evaluation of porous H_(1.6)Mn_(1.6)O_4@chitosan pellet for Li~+ extraction

摘要

Spinel-structured lithium manganese oxide is regarded as one of the most promising materials that can recover Li+ from brine and seawater. Herein, a hierarchical porous and hydrophilic H1.6Mn1.6O4@chitosan pellet (HMO@CP) is proposed and its mechanical property is tailored through the glutaraldehyde-derived cross-linking. Different characterization techniques such as scanning electron microscopy (SEM), Brunner-Emmet-Teller (BET) measurement, Fourier transformation infrared spectrum (FTIR), and X-ray diffraction (XRD) meter were used to investigate the chemical and morphological properties of the HMO@CP. H1.6Mn1.6O4 powders were successfully encapsulated by chitosan, forming composite porous pellets. The equilibrium adsorption capacity of HMO@CP is 49.2 mg center dot g(-1), which is similar to that of the pristine H1.6Mn1.6O4. Moreover, the adsorption behavior of HMO@CP well fits with the pseudo-second-order kinetic model, and the Langmuir model can be used to describe the adsorption isotherm of HMO@CP. Furthermore, the adsorption thermodynamic parameters such as Delta H-theta Delta G(theta) and Delta S-theta were calculated based on the obtained results. When the pellet is immersed into 0.05mol center dot L-1 HCl solution after the Li+ adsorption process, the desorption equilibrium can be reached within 60 min, with a manganese dissolution loss of 2.48%. The Li+ adsorption capacity of HMO@CP remains at 41.92 mg center dot g(-1) after five adsorption-desorption cycles, confirming the effective regeneration property of the HMO@CP. In addition, the as-prepared HMO@CP shows excellent selectivity for Li+ among Na+, K+, Mg2+, and Ca2+ ions in the simulated solution.