Analysis of the interaction in the mixture of organophosphorus acids and Aliquat 336 through the measurement of dielectric constant and viscosity

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

“…Thus, the strong interactions can be responsible for the decrease in the effective concentration of D2EHPA which act as an extractant, resulting in low extraction percentage of Co(II). Besides that, the amine salts or ionic liquids, which can be formed when the strong interaction occurs between acidic extractant (D2EHPA) and Alamine 336/Aliquat 336, can take part in the extraction reaction [4,20]. However, their amount in these mixtures may be not enough for efficient extraction of Co(II) in our experimental conditions.…”

“…After extraction, equilibrium pH was measured and the value of pH eq was displayed in Table 2. In these experiments, the mole fraction of D2EHPA in the mixture was fixed at 0.6 on the basis of the reported literature [5,20]. The concentration of the mixtures and IL was kept at 0.5 M. The concentration of Co(II) was 500 mg•L −1 and the volume ratio of the two phases was unity.…”

“…According to Liu et al, three kinds of interaction may occur between acidic and amine extractant such as (i) ion pair (R 3 NH + A − ), (ii) hydrogen bonding (R 3 NH-A), and (iii) binding which has an intermediate characteristic as represented by the location of the proton [5]. Similarly, the interactions such as dipole interaction, hydrogen bonding, and ion pair are proposed for mixed extractants of D2EHPA and Aliquat 336 on the basis of molecular chemistry [20]. Thus, the strong interactions can be responsible for the decrease in the effective concentration of D2EHPA which act as an extractant, resulting in low extraction percentage of Co(II).…”

“…When the reverse reaction of Equation ( 7) occurs, the concentration of HCl in the aqueous phase would increase, resulting in low extraction percentage of Co(II) [8,22]. The reaction for the formation of IL and the transfer of HCl can be proposed as Equation ( 8) [20].…”

“…According to previous works [20,21], ILs can form when D2EHPA and Aliquat 336 are mixed at a specific composition. However, this prediction was only based on the variation of physical properties of mixture with composition and the shift of characteristic peaks on the spectra such as FT-IR (Fourier-transform infrared spectroscopy), ATR-IR (Attenuated total reflection infrared spectroscopy), and NMR (Nuclear magnetic resonance spectroscopy).…”