Physical and chemical study of manganese dioxide sorbent after sorption of lithium from brines

The article presents the results of the study for the synthesized manganese dioxide sorbent after its saturation with lithium from brine. The sorbent was previously prepared. For this purpose the mixture of manganese oxide compounds was kept with lithium hydroxide in a wet state at 125 °C, calcinated at 450 °C and then the precursor was treated with dilute hydrochloric acid. The process intended to saturate the sorbent with lithium was performed by putting it in contact with a lithium-containing brine with a pH of 8.77 at T = 40°C for 24 hours in four cycles. The sorbent after saturation was studied using X-ray phase and thermal analysis methods. X-ray phase analysis showed that lithium-containing phases are represented by such compounds as Li(Li0.17Mn0.83)2O4 and Li0.78Mn1.88O4. The results of thermal analysis show the possibility of phases to be in the sorbent after saturation LiMn2O4 and Li1,3Mn2O4 phases. The study results showed that ion-exchange interaction takes place between the lithium-ion from the brine and the proton from the manganese-oxide spinel composition to a greater extent during sorption. Besides, the redox nature of the interaction is present during the sorption of lithium. All lithium intercalation reactions proceed topotactically without significant changes in the main structure of the original sorbent.