Removal of Mineral Salts by Heteropoly Acid-Crownether Adduct for Quick Determination of TraceAmounts of Lithium in Natural Brines

摘要

There Is severe Interference by a number of metallic ions found in brines in the determination of lithium by flame atomic absorption and emission spectroscopic methods. The formation of heteropoly acid-crown ether adduct was used for removing the interfering Ions from the brine matrix. The appropriate crown ether was selected to make sure that essentially all lithium ions are left in the solution.Then, the experimental conditions, including the molar ratio of the crown to total cations, the molar ratio of the crown to heteropoly acid were optimized and the influence of acid addition and the stirring time on the measured lithium were Investigated. This is a simple and quick method with adequate accuracy for the determination of lithium in highly concentrated solutions and natural brine samples, which contain trace amounts of lithium. The superiority of this method is that organic solvents are not used. This method has been applied to determine lithium and then to estimate the lithium reserves in the natural brine of the Iranian playa.