Extraction behavior and selective separation of lead(II) using N,N-dioctyldiglycol amic acid.

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