Transport of Cr(VI) from HCl Media Using (PJMTH⁺Cl⁻) Ionic Liquid as Carrier by Advanced Membrane Extraction Processing

Abstract

The transport of Cr(VI) from acidic media through pseudo-emulsion based membrane strip dispersion (PEMSD) containing the ionic liquid (PJMTH⁺Cl⁻) as carrier in the form of a pseudo-emulsion with sodium hydroxide has been investigated. The ionic liquid was generated in situ by reaction of the primary amine Primene JMT and HCl. The transport of Cr(VI) is evaluated as a function of various experimental variables: stirring speed in the feed phase, concentration of Cr(VI) and HCl in the feed phase, carrier concentration, and organic diluents in pseudo-emulsion, and NaOH concentration in pseudo-emulsion as strippant. In PEMSD, pseudo-emulsion is an emulsion that is formed temporarily between the organic and the stripping solutions. Both solutions are separated when the stirring device is stopped. The value of the overall permeation coefficient obtained under standard experimental conditions was 3.1 × 10⁻³ cm s⁻¹, whereas the transport process is controlled by diffusion of chromium species in the stagnant film of the feed phase. The performance of the system against other carriers (amines, quaternary phosphonium salt and quaternary ammonium salt) was also evaluated.

Keywords:

• chromium(VI)
• (PJMTH⁺Cl⁻) ionic liquid
• metal transport
• pseudo-emulsion membrane strip dispersion (PEMSD)

ACKNOWLEDGEMENTS

The authors thank the CSIC (Spain) for support to carry out this work and I. García-Díaz for the contract JAEDoc_09-00893 (CSIC).

Notes

Source phase: Cr(VI) 0.01 g L⁻¹ in 0.1 M HCl; Organic/stripping phase: (PJMTH⁺Cl^-) 10% v/v in cumene and 0.1 M NaOH.

Source phase: 800 rpm 0.01 g L⁻¹ Cr(VI) and HCl. Organic/stripping phase: (PJMTH⁺Cl⁻) 10% v/v in cumene and 0.1 M NaOH.

Source phase: 800 rpm, 0.01 g L⁻¹ Cr(VI), 0.1 M HCl. Organic/stripping phase: (PJMTH⁺Cl^-) 10% v/v in cumene.

^a After 3 h.

Source phase: 800 rpm, 0.01 g L⁻¹ Cr(VI), 0.1 M HCl. Organic/stripping phase: (PJMTH⁺Cl^-) 10% v/v and 0.01 M NaOH.

^a After 3 h.

Source phase: 800 rpm, 0.01 g L⁻¹ Cr(VI), 0.1 M HCl. Organic/stripping phase: 10% v/v different carrier in cumene and 0.01 M NaOH.

^a After 3 h.