Lithium Recovery from Reverse Osmosis Concentrate of Geothermal Water by Spinel Type λ-MnO2 -Batch Tests

Powder and granulated forms of lithium selective spinel type manganese oxide adsorbents (lambda-MnO2) were evaluated for adsorption of lithium from the reverse osmosis (RO) concentrate of geothermal water. The interaction between lithium ions and lambda-MnO2 adsorbents, in terms of adsorption capacity and uptake rate, was investigated by equilibrium and kinetic studies. In terms of adsorption equilibria, Langmuir isotherm adsorption model accurately represented the adsorption of lithium ions by powder and granulated lambda-MnO2 adsorbents from the RO concentrate of the geothermal water. The best description of lithium uptake onto powdered and granulated adsorbents was provided by the pseudo-second-order kinetic model. Additionally, research was carried out with an objective of removing the inhibitory impacts of boron and arsenic on separation of lithium. The lambda-MnO2 adsorbent showed no affinity for boron uptake from the solution. However, it exhibited some increasing uptake to arsenic with an increase in amount of the lambda-MnO2 adsorbent. But it is possible to eliminate arsenic by means of arsenic selective ion exchange resins Lewatit FO36 and ArsenXnp prior to separation of lithium from the RO concentrate of geothermal water.