N, N'-Bis(salicylidene)ethylenediamine (Salen) as an Active Compound for the Recovery of Ni(II), Cu(II), and Zn(II) Ions from Aqueous Solutions

Katarzyna Witt; Daria Bożejewicz; Małgorzata A Kaczorowska

doi:10.3390/membranes10040060

N, N'-Bis(salicylidene)ethylenediamine (Salen) as an Active Compound for the Recovery of Ni(II), Cu(II), and Zn(II) Ions from Aqueous Solutions

Membranes (Basel). 2020 Apr 2;10(4):60. doi: 10.3390/membranes10040060.

Authors

Katarzyna Witt¹, Daria Bożejewicz¹, Małgorzata A Kaczorowska¹

Affiliation

¹ Faculty of Chemical Technology and Engineering, UTP University of Science and Technology, 3 Seminaryjna, PL 85326 Bydgoszcz, Poland.

Abstract

In this paper, three main methods of metal ion separation, i.e., liquid-liquid extraction, transport across polymer inclusion membranes (PIMs), and sorption/desorption, are described. In all of them, N,N'-bis(salicylidene)ethylenediamine (salen) was used as an active compound, i.e., as an extractant or as a carrier for the recovery of Ni(II), Cu(II), or Zn(II) ions from aqueous solutions. In each case, the recovery was performed on a model solution, which contained only a single metal ion. The obtained results were compared with the author's previous results for the separation of metal ions using β-diketones, since both β-diketones and salen form the so-called Werner-type complexes. Electrospray ionization high-resolution mass spectrometry (ESI-HRMS) was also applied to confirm the ability of the carrier to form complexes with metal ions in a solution. Moreover, spectrophotometry was used to determine the stability constant of the obtained complexes.

Keywords: N,N’-bis(salicylidene)ethylenediamine; metal ions; nickel(II), copper(II), zinc(II), liquid–liquid extraction; polymer inclusion membranes; salen; sorption.