Extraction Behavior and Selective Separation of Lead(II) Using N,N-Dioctyldiglycol Amic Acid

Abstract

Selective separation of lead ions (Pb²⁺) from aqueous solutions containing multiple divalent metal ions (Pb²⁺, Cu²⁺, Cd²⁺, Zn²⁺, Mn²⁺, Co²⁺, and Ni²⁺) was investigated using liquid–liquid extraction. N,N-Dioctyldiglycol amic acid (DODGAA) enabled quantitative extraction and efficient separation of Pb²⁺ from the metal ion mixture under mildly acidic conditions. Compared with conventional commercial extractants, DODGAA provided better extraction and excellent selectivity for Pb²⁺. The extraction of Pb²⁺ with DODGAA proceeded through a proton-exchange reaction and formed a 1:2 complex, Pb(DODGAA)₂. The Pb²⁺ was readily stripped from the extracting phase under acidic conditions, and the organic solution with DODGAA could be recycled.