A Theoretical Study Of Adsorption Of Lithium Ion On Goethite Surface In Aqueous Solution

According to molecular dynamics theory, using COMPASS force field to modelthe adsorption phenomena of lithium ions on goethite （010） advantage crystal surface,dynamics simulation of the adsorption process has been done by Materials Studio Discover module. The results show that the lithium ions can be adsorbed on thesurface of the goethite spontaneously under certain conditions.NPT simulation of an aqueous solution of lithium chloride gives the role to Li⁺and H2O. The results show that, Li⁺had a great solubility in water and the dissolutionprocess is exothermic.There is the van der Waals force between Li⁺and watermolecules.The phenomenon that different concentrations of Li⁺adsorbed on the surface ofα-FeOOH has been performed in NVT ensemble. The results show that the Li⁺adsorption is an exothermic process, and the adsorption rate increases with theconcentration of Li⁺, but most of the Li⁺tends to the diffusion layer.Under the same concentration of Li⁺, the adsorption’s temperature and pressuresimulation have been studied. The results show that if the pressure is constant, thetemperature rises, Li⁺adsorbance is first reducing and then increasing, in line withgeneral laws of solid adsorption. The adsorption of Li⁺on goethite （010） surface isphysical adsorption and chemisorption together. Enhancing the temperature of thesolution to room temperature may increase the amount of adsorption of Li⁺.NVT adsorption simulation of Na⁺and Mg²⁺two cationic interfering ions hasbeen done. The results indicate that Mg²⁺affects the Li⁺adsorption rate greater thanNa⁺. The presence of other salts weakens the adsorption or even makes it difficult toadsorb spontaneously. The adsorption of Li⁺on goethite surface is spontaneous, but itis greatly influenced by the accompanying ions in aqueous solution.The research results may provide a theoretical basis for the lithium extractionmethod from seawater or brine.