The Liquid-Liquid Extraction of Toxic Metals (Cd, Hg and Pb) by Calixarenes

Toxic metals (Cd, Hg and Pb) are mostly present in the environment due to natural phenomenon and human activities as well. Exposure of these non-essential elements in the environment causes severe effects. They are known to cause problems in humans as well as in aquatic life. In this work, we demonstrate various studies regarding liquid-liquid extraction of selected ions with different functionalized calixarenes. This review article briefly discusses several molecular designs of calixarenes for divalent ion (Cd2+, Hg2+ and Pb2+) recognition; as well as the relationship between structure and selectivity of the macrocycles is elaborated. The article does not, however, attempt to cover all of the different approaches to these toxic metal ions extraction.