Synergistic extraction of iron(III) at higher concentrations in D2EHPA-TBP mixed solvent systems

Abstract

The extraction of iron(III) from chloride solutions at macrolevel concentration by different solvents such as tri-n-butyl phosphate (TBP), di(2-ethylhexyl) phosphoric acid (D2EHPA), and their mixture in various proportions has been investigated at different acid concentrations. The synergistic extraction of iron(III) with a mixture of TBP and D2EHPA was studied and the results were compared with that of the extraction by individual solvent alone. An increase in the concentration of the synergist, TBP, in the D2EHPA-TBP solvent system resulted in an increase in the synergistic coefficient value. The experimental data are treated graphically to explain the formation of organic phase extracted species, and the equilibrium extraction constants for the species are determined. It is found that a maximum of two molecules of TBP are adducted to the extracted species of the corresponding nonsynergistic system. Stripping of iron(III) with hydrochloric acid from loaded D2EHPA was found to increase with an increase in acid concentration. In the case of D2EHPA-TBP mixtures, stripping efficiency was increased with an increase in acid concentration up to a certain level and then it was decreased. The experimental results indicate that an iron exchange reaction between loaded D2EHPA and TBP proceeds during stripping at a higher concentration of hydrochloric acid (from mixed loaded solvent system). A plausible mechanism for iron(III) extraction and stripping has been discussed.

Stripping of Fe(III) from the Loaded Mixture of D2EHPA and TBP with Sulfuric Acid Containing Reducing Agents

“…Therefore, the mixture of 1 M D2EHPA and 1 M TBP was employed in further experiments. In our experimental range, the solvent extraction reaction of iron by the mixture of D2EHPA (RH) and TBP (L) can be represented as 13,14 :…”

“…11,12 An alternative method to overcome this difficulty has been developed by employing the mixture of D2EHPA and TBP for the extraction of Fe. [13][14][15][16] It was found that the mixture of D2EHPA and TBP exhibited better extraction ability than single extractant 13,14 and the stripping of Fe(III) from the mixture of D2EHPA and TBP was easier than that from D2EHPA alone. 15,16 Although the use of mixture of D2EHPA and TBP can increase the extraction and stripping efficiency of Fe, it is still difficult to strip most of Fe when the concentration of loaded iron is high.…”

An Integrated UV-Vis Microfluidic Device for the Study of Concentrated Solvent Extraction Reactions

“…Kinetic determinations are necessary to understand the extraction mechanism. However, the heterogeneous nature of SX reactions makes kinetic determinations challenging [2], especially at high concentrations which are relevant to industrial applications [1,5,6]. The preferred tool for SX kinetic investigations has been the Lewis cell [7,8].…”

Mixed solvent systems for the extraction and stripping of iron(III) from concentrated acid chloride solutions

“…[13,15] In order to overcome these difficulties, sevtime was longer than 5 minutes. After phase separation, the eral researchers [6,[19][20][21] and the present authors [22,23] have concentration of iron(III) in the raffinate was analyzed by reported synergistic solvent extraction and an associated the SnCl 2 reduction method. [24] The distribution coefficient improvement in iron(III) stripping using various mixed (D) was obtained from the ratio of the equilibrium concentraextractants.…”