Abstract
To conduct experiments related to the facilitated extraction phenomenon of vanadium ions (VO2+), three supported liquid membranes (SLMs) were prepared, each containing 0.01 M of methyl cholate (MC), resorcinarene (RESO), or trioctylamine (TOA) as extractive agents. Kinetic and thermodynamic models were developed, based on the interaction of the substrate (VO2+) with the extractive agent T and the diffusion of the formed entity (TS) through the membrane. The experimental results verify the models, and to determine, macroscopic parameters, permeabilities (P) and initial fluxes (J0), and microscopic parameters, association constants (Kass) and apparent diffusion coefficients (D⁎) related to formed entities (TS) and their diffusion through the membrane organic phase. The experimental results indicate that the mechanism on the migration of the VO2+ ions through the membrane organic phase is based on the successive jumps of substrate, from one site to another of the extractive agent. To explain these results and understand the mechanism, we studied influence of temperature factor, and we determined activation parameters (Ea, ΔH≠, and ΔS≠). The results show that this extraction phenomenon is governed by a structural term. Therefore, the membrane performance changes according to nature and structure of the association site presented by each of extractive agents.
Highlights
Conventional industrial techniques of extraction and separation by distillation or crystallization have a high cost, since they require large amounts of energy and use polluting organic solvents
Three supported liquid membranes (SLMs) were prepared with same polymer support (PVDF), same organic phase, and three different extractive agents (TOA, methyl cholate (MC), and RESO). These three SLMs were adopted for the facilitated extraction process of VO2+ ions from concentrated acidic environments
The obtained results show that prepared SLMs are highly permeable for the extraction process of
Summary
Conventional industrial techniques of extraction and separation by distillation or crystallization have a high cost, since they require large amounts of energy and use polluting organic solvents. The supported liquid membranes (SLMs) are part of these membrane processes types; they have a major economic and environmental interest, since they are necessary for the treatment of liquid mediums, contaminated with metal ions or organic compounds. A very low uses of organic solvents, which today an important criterion for the protection of the environment and the treatment of toxic effluents. These processes permit continuous operation in a single step, since the two steps extraction and reextraction are so coupled to the two interfaces. The membranes are thin films that separate two fluids; an essential property of membranes is their permeability and
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