Synthesis of aluminum-doped ion-sieve manganese oxides powders with enhanced adsorption performance

Al-doped lithium manganese oxides Li1.6AlxMn1.6-xO4 were successfully prepared by sol-gel synthesis and solid state reactions. Protonated samples were obtained by further acid treatment. Experiments were performed to study the effects of physical properties including the Al3+ doping content x and calcination temperature for optimizing the synthesis of H1.6AlxMn1.6-xO4 ion-sieve pursing nice performance such as enlarging the adsorption capacity and minimizing dissolution loss of manganese. The characteristics of a series of Al-doped ion-sieve were studied by XRD, SEM and EDS. The crystal structure was kept well after Al doping from XRD analysis. SEM and EDS showed that Al was uniformly distributed in the sample. The valence state of Mn in Al-doped ion-sieve precursor was analyzed by XPS. Adsorption/desorption experiments were carried out to evaluate the amounts of lithium extraction, lithium adsorption capacity and the manganese and aluminum dissolution loss of the ionsieve. The results showed that the Al-doped H1.6Mn1.6O4 ion-sieve exhibited higher absorption capacity (which approached 32.6 mg g(-1) while the undoped one reached only 27.6 mg g(-1)). Furthermore, the dissolution loss of manganese and aluminum from the Al-doped ion-sieve were the most impressive among the ones. Importantly, the Al-doped ion-sieve still preserve a high adsorption capacity (26.8 mg g(-1)) and pretty low manganese dissolution loss (1.92%) after performing up to 4 cycles of adsorption/desorption experiments, indicating an enhanced stability of the Al-doped H1.6Mn1.6O4 ion-sieve.