Enhanced extraction of lanthanides with crown ether carboxylic acids of increasing lipophilicity

Abstract

sym-Dibenzo-16-crown-5-oxyacetic acid and its modified analogues can extract lanthanides efficiently in solutions with high ionic strength and complex matrices. Increasing the length of the side-arm alkyl group increases the lipophilicity of the macrocyclic polyether and enhances the distribution ratio of the lanthanide complexes in the organic phase. This type of crown ether carboxylic acid is a potential complexing agent for selective extraction and concentration of lanthanides in natural water systems.