Determination of the Solubility of Copper with Three Commercial Ligands and One Novel Ligand in Supercritical CO₂

Abstract

The solubility of four copper ligand systems in supercritical (SC) CO 2 was studied. Three of the ligand systems studied were commercial ligands, while the last one was a new Schiff base reduced macrocyclic ligand. The three commercial ligands were ethylenediaminetetraacetic acid (EDTA), diisooctylphosphinic acid (DiOPA), and the anion-exchanger Aliquat 336 (methyltrioctylammonium chloride). The Schiff base reduced macrocyclic ligand was 3,6,9,12-tetraaza-4(1,2),11(1,2)-dibenzena-1(1,3)-pyridinacyclotridecaphane (TeDiPyDeca), which forms a very stable 1 + 1 copper complex Keq = 2 42 × 10 6 . This article presents the synthesis, Fourier transform infrared spectroscopy (FT-IR) studies, and crystal structure of the new copper complex Cu(TeDiPyDeca) as well as experimental data of solubility fitting with a Peng Robinson equation and van der Waals mixing rules. The molar volume of the solid (Vs), the vapor pressure (Pvap), and the binary interaction coefficient k ij of the four metal complexes were found. The physical effects of the molecular forms of the studied copper complexes were the most important factors in regard to solubility in SC CO 2 .

Strategies for the Separation of the Furanic Compounds HMF, DFF, FFCA, and FDCA from Ionic Liquids

“…Higher FFCA solubility at higher water content suggests an interaction of the water with the aldehyde group to form geminal diols, which has already been demonstrated in other reports. 51,52 While outside the scope of the present work, further insight could be obtained using thermodynamic modeling 53,54 to explain the interaction of the ions and water with FFCA and FDCA.…”