Improvement of Gd(III) Solvent Extraction by 4-Benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one: Non-Aqueous Systems

Abstract

The study of the liquid–liquid extraction of gadolinium (Gd(III) ion) with a chelating compound, 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP), and the determination of the process parameters are presented by employing two ionic liquids, namely, ([C1Cnim+][Tf2N−], n = 4, 10) and CHCl3, as diluents. Compared to CHCl3, the ionic liquid offers increased distribution ratios in an aqueous medium. A step forward, enhanced solvent extraction, and improved separation upon the addition of ethylene glycol are demonstrated, i.e., a boost of two immiscible organic phases, compared to traditional aqueous solutions. However, this is noticeable when using CHCl3, but unfortunately not with ionic liquid combination, [C1C10im+][Tf2N−]. Several conclusions are given, highlighting the role of the ionic diluent in complexation processes and selectivity with an employment of the chelating agent HP for various metal s-, p-, d-, and f-cations, i.e., nearly 25 metals. A detailed evaluation of the selectivity between these metals was made when changing both the aqueous phase completely with ethylene glycol or partially with glycerol (1:1). Electron paramagnetic resonance (EPR) spectroscopy has been used to study the established chemical species in the obtained organic extracts, such as Gd3+, Fe3+, Cu2+, and Cr3+, with unpaired electrons.

Recent Uses of Ionic Liquids in the Recovery and Utilization of Rare Earth Elements

“…Gd(III) was extracted by 4-benzoyl-3-methyl-1-phenyl-2-pyrazolin-5-one (HP) using [C1Cnim + ][NTf2 -] (n= 4 or 10) ionic liquid [51]. The investigation compared conventional solvent extraction procedure (aqueous and organic phases) with the use of two inmiscible organic phases.…”

Mutual Solubilities between Ethylene Glycol and Organic Diluents: Gas Chromatography and NMR

“…As a result, among the many environmentally benign issues today is the viability of the suitable use of some organic liquid compounds as replacements of water in chemical technology. As a whole, applications of ethylene glycol compound have been summarized in a number of excellent investigations with regard to its potential use in separation processes [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. However, attention must be paid to the chemical nature, toxicity, and biodegradation of such compounds apropos their solubility in water, which poses serious concern regarding their possible entry into ecosystems.…”