Lithium removal from seawater via liquid membrane transport using 12-crown-4 as a carrier and study of the effect of carbon nanotubes as a membrane additive

Abstract

In this work, transport of lithium (Li) ions from seawater into an aqueous phase was performed by using a liquid membrane (LM) and 12-crown-4 as a carrier. Influential parameters on the extraction efficiency of Li including the pH of the feed and receiving phases, type of membrane solvent, carrier concentration, type & concentration of the stripping reagent in the receiving phase and its pH, temperature and time of transport were investigated and optimized. The effect of carbon nanotubes (CNTs) as an additive on the transportation of Li ions was evaluated. The results show that single walled carbon nanotubes (SWCNTs) have a positive effect on the Li transportation. Under the optimized conditions, the maximum Li transportation from the feed into the receiving phase was 12.0%. The selectivity of the proposed method in the presence of interfering ions such as Na⁺, K⁺, Ca²⁺ and Mg²⁺ was more satisfactory than that of reported methods. The method was successfully applied for the separation of Li from seawater samples.