Extraction of lithium from seawater (Persian Golf) bittern via magnetite nanoparticles

Lithium is a very strategic metal and the source of energy for the world in the future. Due to the lack of lithium mineral resources, in this study, the extraction of lithium from the bittern of salt extraction ponds from seawater was evaluated. In order to selectively adsorb lithium from the bittern solution, magnetite nanoparticles were first synthesized by co-precipitation in the presence of ammonium hydroxide. Due to the instability and the tendency of these nanoparticles to agglomerate in solution, their surface was coated with silicate surfactant. Silica surface coating on magnetite nanoparticles was performed using tetraethyl orthosilicate precursor with a concentration of 1 ml by sol-gel process. Magnetite nanoparticles stabilized by organosilane aminopropyl thromotoxy silane (C6H17NO3Si) were functionalized and used for adsorption experiments. At a stirrer speed of 30 rpm, a duration of 40 min and a solid to liquid ratio of 9 g / l, about 97.1% lithium was extracted from the bittern solution. Under these conditions, the extraction of K and Mg elements was negligible and 4 and 6%, respectively, but the extraction of sodium was equal to 34%. Washing and separation of lithium and sodium from the surface of nanoparticles was performed by the ammonium compound NH4OH and NH4Cl, which washed 99% of lithium in 150 min, but only about 55% of sodium was washed at the same time.