Physicochemical parameters of lithium sorption from hydromineral raw materials using synthesized inorganic sorbents

This paper presents the results of a study on the physicochemical parameters of the lithium sorption process from hydromineral raw materials using synthesized sorbents. The physicochemical parameters of lithium sorption from brine, including the enthalpy change (ΔH, kJ/mol), entropy change (ΔS, kJ/mol·K), and Gibbs free energy (ΔG, kJ/mol), were investigated. The enthalpy value ΔH = -0.698 kJ/mol indicates that the process is exothermic, as it is accompanied by heat release. The positive value of entropy ΔS = 0.0122 kJ/(mol·K) indicates a low degree of order and increased randomness at the interface between the manganese dioxide-based sorbent and the brine during lithium absorption. The negative Gibbs free energy (ΔG) values, ranging from -4.401 to -4.769 kJ/mol at temperatures of 303–333 K, confirm that the lithium sorption process on the manganese oxide sorbent is spontaneous and can proceed without external influence. Additionally, the activation energy value Ea = -0.592 kJ/mol suggests a decrease in the sorption rate as the temperature increases. Using a modified Arrhenius-type equation, the adhesion probability S* was determined to be 0.188. This value indicates the predominance of the chemisorption mechanism in the lithium sorption process.