New family of Type V eutectic solvents based on 1,10-phenanthroline and their application in metal extraction

abstract

Although a theoretically extensive number of hydrophobic eutectic mixtures suitable for solvent extraction are obtainable, to date reported mixtures rely on a limited number of chelating groups, namely phosphine oxide, carboxylic acid, and ketones. Herein, a new family of Type V Deep Eutectic Solvents (DES) based on the poly-pyridyl ligand 1,10-phenanthroline (phen) is presented with the aim of facilitating the extrapolation of the disclosed findings to other potential systems based on phen or bipyridine derivatives. The hydrophobic eutectic solvent composed of the natural phenolic extract thymol with phen exhibits a solid-liquid phase diagram with a useable liquidus compositional range on the thymol-rich side. The physical properties of the mixture are dependent on the presence of solutes liable to change the nature of the existing hydrogen-bonded network, most notably through the protonation of phen. The metal chelating ability of phen are retained when included as a DES component. Quantitative extraction of various transition metals cations (Cd(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)) as well as the platinum group metal Pd(II) was obtained across a range of solvent compositions. The extraction of Li(I), Mn(II), Co(II) and Ni(II) was further studied as a function of the aqueous phase pH, with the extent of metal partition decreasing with the protonation of phen at pH values below 1.0. Building upon the luminescent properties of phen, the eutectic solvent was further applied as a simultaneous pre-concentration and quantification medium for Fe(II/III), allowing for the facile UV-vis detection of Fe up to 12 mu g L-1.

keywords

PYRIDINDERIVATE ALS KOMPLEXBILDNER; MOLECULAR-DYNAMICS; FLUORESCENT-PROBE; BINARY-MIXTURES; LIGAND DESIGN; PHENANTHROLINE; COMPLEXES; WATER; FE2+; 10-PHENANTHROLINE

subject category

Metallurgy & Metallurgical Engineering

authors

Crema, APS; Schaeffer, N; Bastos, H; Silva, LP; Abranches, DO; Passos, H; Hespanhol, MC; Coutinho, JAP

Groups

G4 - Renewable Materials and Circular Economy
G6 - Virtual Materials and Artificial Intelligence

Projects

CICECO - Aveiro Institute of Materials (UIDB/50011/2020)

CICECO - Aveiro Institute of Materials (UIDP/50011/2020)

Associated Laboratory CICECO-Aveiro Institute of Materials (LA/P/0006/2020)

PTNMR - Portuguese Nuclear Magnetic Resonance Network (REDE/1517/RMN/2005)

acknowledgements

This work was developed within the scope of the project CICECO- Aveiro Institute of Materials, UIDB/50011/2020, UIDP/50011/2020 & LA/P/0006/2020, financed by national funds through the FCT/MEC (PIDDAC). NMR analysis was made possible through the National NMR Network, funded within the framework of the National Program for Scientific Reequipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT. M.C. Hespanhol acknowledges Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior/Fundacao para a Ciencia e Tecnologia (CAPES/FCT 88881.309048/2018-01). A.P.S. Crema acknowledges CAPES for her fellowship (88887.474466/2020-00). H. Passos acknowledges FCT, I.P., under the Scientific Employment Stimulus Individual Call (CEECIND/00831/2017). N. Schaeffer acknowledges the national funds (OE), through FCT in the scope of the framework contract foreseen in the numbers 4, 5 and 6 of the article 23, of the Decree-Law 57/2016, of August 29, changed by Law 57/2017, of July 19.