Solvent extraction and stripping of lithium ion from aqueous solution and its application to seawater

For the development of lithium ion recovery process from seawater, a series of experimental researches were performed. Solvent extraction of lithium ion from aqueous solution using kerosene as solvent was proposed. Lithium ion is effectively extracted by thenoyltrifluoroacetone–trioctylphosphine oxide (TTA–TOPO) in kerosene within 80 min. Extraction efficiency is severely influenced by stoichiometric parameters. Among the stoichiometric parameters, volume ratio of aqueous (A) to extraction (E) solution is the most influential parameter. After extraction, lithium ion could be easily stripped from the extraction solution by acidic solutions. Stripping efficiency decreases with pH of acidic solutions, and the kind of acid does not affect the stripping efficiency. Extraction efficiency maintains at more than 93 % even when the extraction solution is recycled three times. 65 % of lithium ion can be extracted from seawater by this solvent extraction process when magnesium ion is precipitated by NH₄OH prior to solvent extraction process. Other metallic ions in seawater decrease the extraction efficiency of lithium ion.