Selective lithium extraction and concentration from diluted alkaline aqueous media by a polymer inclusion membrane and application to seawater

Abstract A method capable of selectively extracting and concentrating lithium from diluted alkaline aqueous media is proposed using a polymer inclusion membrane composed of cellulose triacetate (CTA) and the carriers LIX-54-100 and Cyanex 923 without the addition of plasticizer. Transport conditions were optimized using the modified simplex algorithm. The system can transport lithium against its concentration gradient due to a coupled hydrogen ions countertransport. Under optimized conditions, the membrane can be reused up to 10 times before losing 40% of its initial capacity. Using the proposed system, lithium can be concentrated from diluted aqueous media in presence of high quantities of other metallic cations to get a lithium chloride solution from which it would be easier to get valuable high purity lithium compounds. The membrane was used to extract and concentrate lithium from synthetic and natural seawater and good selectivity and recovery were achieved.