Application of a new TOPO-Cuprone type V deep eutectic solvent as a carrier of Zn(II), Cd(II), Pb(II) and Cu(II) ions in polymer inclusion membranes. Chemometric methods for new hydrogen bond acceptor (HBA) selection

Abstract

A new hydrogen bond donor was selected as a deep eutectic solvent (DES) component using 0D, 1D, and 2D molecular descriptors and chemometric methods such as hierarchical cluster analysis (HCA) and principal component analysis (PCA). Compared to typical substances used as hydrogen bond donors (HBDs), namely carboxylic acids, it was found that α-benzoin oxime (Cuprone), despite of its different properties, is also a suitable DES constituent. A new DES was synthesized and applied as a carrier of Zn(II), Cd(II), Pb(II), and Cu(II) ions in polymer inclusion membranes (PIMs). Tri n-octyl phosphine oxide (TOPO) was applied as a hydrogen bond acceptor (HBA), and Cuprone was used as the HBD in the 2:1 M ratio, respectively. The transport properties of a new DES were compared with PIM systems in which TOPO:benzoic acid, TOPO:dodecanoic acid, and pure TOPO were applied. The selected physicochemical properties such as density, viscosity, and thermal stability of the new DES were examined. The transport and separation of Cd(II), Zn(II), Pb(II), and Cu(II) ions from chloride media using a new DES as a carrier were investigated. The influence of the carrier content and the presence of a plasticizer on transport efficiency during long-lasting experiments were also examined.It was found that the observed membrane transport selectivity order Zn(II) > Cd(II) > Pb(II)≫Cu(II) results from the presence of TOPO in the newly prepared DES. Moreover, systems with a plasticizer exhibit high operational stability during long–term experiments lasting over 500 h. Some drawbacks which appeared during the transport experiments were noticed and described in detail.