Polyaza macroligands as potential agents for heavy metal removal from wastewater

Two polyaza macroligands N,N′-bis(2-aminobenzyl)-1,2- ethanediamine (L1) and 3,6,9,12-tetraaza-4(1,2),11(1,2)-dibenzo-1(1,3)- piridinaciclotridecafano (L2) were characterized and investigated for their metal ion extraction capabilities. The nature of all complexes was established by spectroscopic techniques. The equilibrium constants were determined by spectrophotometric and potentiometric techniques and the residual concentration of metals in the solutions by Atomic Absorption Spectrometry (AAS). The capacity of the ligands to remove heavy metals such as Cu(II), Ni(II), Cd(II), Zn(II) and Pb(II) as insoluble complexes was evaluated in wastewater from industrial effluents. These agents showed high affinity for the studied metals. The values of equilibrium constants of the isolated complexes (between 1 x 104 and 2 x 107) demonstrated the feasibility of applying these chelating agents as an alternative to remove heavy metals from industrial effluents.