Comparison of Extraction Ability between a Mixture of Alamine 336/Aliquat 336 and D2EHPA and Ionic Liquid ALi-D2 from Weak Hydrochloric Acid Solution

Viet Nhan Hoa Nguyen,Minh Nhan Le,Man Seung Lee

doi:10.3390/met10121678

Abstract

The development of extraction systems to improve the extraction efficiency of metals using commercial extractants and ionic liquids is of importance. The extraction behavior of Co(II) between mixture of Alamine 336/Aliquat 336 and D2EHPA and synthesized ionic liquid ALi-D2 was compared in this work. Some factors, such as equilibrium pH, properties of the extractants, and concentration of components in the mixture had a remarkable effect on the extraction of Co(II). The interactions occurring in the mixtures as well as the change in solution pH were analyzed. Co(II) was completely extracted by ionic liquid when equilibrium pH was higher than 6.5, while it was difficult to extract Co(II) by employing the mixture of D2EHPA and Alamine 336/Aliquat 336. The formation of ionic liquid in the mixture of D2EHPA and Aliquat 336 was verified through FT-IR spectra. In addition, the competition extraction of hydrogen ion and Co(II) by ionic liquid ALi-D2 was explained. Among the three kinds of extractants, the ionic liquid showed the best extraction efficiency for Co(II) and pH control from weak acidic solutions. The present study provides valuable information on the extraction behavior of metal ion by the mixtures of commercial extractants, and thus can give some light on the development of metal extraction systems.

Highlights

In hydrometallurgy, solvent extraction is considered to be an efficient method for the separation and recovery of valuable metals from the leaching solution of primary and secondary sources
The present study provides valuable information on the extraction behavior of metal ion by the mixtures of commercial extractants, and can give some light on the development of metal extraction systems
To investigate the effect of pH on Co(II) extraction by the mixture of D2EHPA and Alamine 336/Aliquat 336 and ionic liquids (ILs) (IL ALi-D2), extraction experiments were performed by varying initial pH of the solution from 1 to 5

Summary

Introduction

Solvent extraction is considered to be an efficient method for the separation and recovery of valuable metals from the leaching solution of primary and secondary sources. In solvent extraction with mixtures of extractants, the efficiency and selectivity of the extractant mixtures greatly depend on some parameters such as the properties of the constituent extractants, the composition of the mixture, the nature of diluent, and the presence of salts in the aqueous solutions [1,2,3,4,5,6,7,8] Among these factors, the interactions occurring in the mixtures have a significant effect on the extraction behavior of metal ions by the mixtures [8]. The dual function of synthesized ILs has been noted in recent studies because these synthesized ILs show good separation of metals and extraction of hydrogen ions which contribute to control solution pH, resulting in favorable extraction [3,18]. This work provides important information for the selection of adequate binary mixtures and the development of efficient metal extraction systems

Reagents and Analysis

Procedures

Results and Discussion

Variation of the pHeq by Single D2EHPA and the Mixtures

Comparison of the Characteristics of the Extractants by FT-IR Spectra

Conclusions