Please use this identifier to cite or link to this item:
Title: Factors driving metal partition in ionic liquid-based acidic aqueous biphasic systems
Author: Carreira, Ana R.F.
Passos, Helena
Schaeffer, Nicolas
Svecova, Lenka
Papaiconomou, Nicolas
Billard, Isabelle
Coutinho, João A.P.
Keywords: Liquid-liquid extraction
Alternative solvents
Metal separation
Ion-pair mechanism
Issue Date: 2022
Publisher: Elsevier
Abstract: The factors influencing metal partition in acidic aqueous biphasic systems (AcABS) containing phosphonium-based ILs are still poorly explored. To assess their influence the effect of the IL counter anion, acid and its concentration, and temperature, were systematically evaluated on the extraction of four transition metals (Cu(II), Co(II), Ni(II), and Mn(II)) and the lanthanide Ce(IV). The AcABS based on HCl showed good ability to extract Co(II) and Cu(II) to the IL-rich phase. In contrast, AcABS based on H2SO4 showed overall poor metal extraction, except for the [P44414]Cl + H2SO4 + H2O system. The latter showed good Cu(II) affinity at higher H2SO4 concentrations. The biphasic systems based on HNO3 were unable to extract transition metals to the IL-rich phase, with chloride from [P444414]Cl hampering Ce(IV) extraction. The [P44414]Cl + H2SO4 + H2O system was further optimized by adding small amounts of HCl to the system. The extraction efficiency of the metals is linked to the charge density of the metal-complex and its inherent free energy of hydration, the anion/water molar ratio changes induced by temperature and ionic strength, and the dissociation degree of the acid. By using these parameters it was possible to tune the selectivity and efficiency of the AcABS. Moreover, metal extraction was found to preferentially occur via an ion-pair mechanism, with split anion extraction taking place in AcABS containing different anions.
Peer review: yes
DOI: 10.1016/j.seppur.2022.121720
ISSN: 1383-5866
Appears in Collections:CICECO - Artigos

Files in This Item:
File Description SizeFormat 
#Manuscript.pdf524.03 kBAdobe PDFView/Open
#SI.pdf498.59 kBAdobe PDFView/Open

Formato BibTex MendeleyEndnote Degois 

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.