What is it about?
Cobalt has been extracted from dilute sulfate solutions by supported liquid membrane (SLM) and solvent extraction (SX). The flux values in SLM process and distribution coefficient in SX has been compared. The microporous hydrophobic PVDF film has been used as the solid support for the liquid membrane. The Cyanex 272 has been used as extractant and mobile carrier in SX and SLM respectively. Sulfuric acid was used as a stripping agent. In both the process effect of different parameters such as pH of feed solution, Cyanex 272 concentrations, cobalt ion concentration in feed phase, strip acid concentration on cobalt flux JCo(II) and distribution coefficient Dsx of cobalt has been investigated. Complete removal of cobalt from dilute sulphate solution at pH of 6.00, using 750 mol/m3 of Cyanex 272 and strip acid concentration 25 mol/m3 has been achieved by SLM process. At the optimum condition of both the studies the flux value of 63.79 x 10-6 mol/m2.s. and distribution coefficient of 1136 has been achieved for SLM and SX process, respectively.
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Why is it important?
Cobalt has been extracted from dilute sulfate solutions by supported liquid membrane (SLM) and solvent extraction (SX). The flux values in SLM process and distribution coefficient in SX has been compared. The microporous hydrophobic PVDF film has been used as the solid support for the liquid membrane. The Cyanex 272 has been used as extractant and mobile carrier in SX and SLM respectively. Sulfuric acid was used as a stripping agent. In both the process effect of different parameters such as pH of feed solution, Cyanex 272 concentrations, cobalt ion concentration in feed phase, strip acid concentration on cobalt flux JCo(II) and distribution coefficient Dsx of cobalt has been investigated. Complete removal of cobalt from dilute sulphate solution at pH of 6.00, using 750 mol/m3 of Cyanex 272 and strip acid concentration 25 mol/m3 has been achieved by SLM process. At the optimum condition of both the studies the flux value of 63.79 x 10-6 mol/m2.s. and distribution coefficient of 1136 has been achieved for SLM and SX process, respectively.
Perspectives
The comparative studies for the extraction of cobalt using two different processes SX and SLM were carried out applying Cyanex 272 as extractant and mobile carrier respectively. Following conclusions can be drawn from above studies. (a) For equilibrium studies, the percentage extraction of cobalt increased with increases in extractant concentration. The slope analysis study of logD vs. log [extractant] indicates that 2 moles of the extractant was involved with 1 mole of the extracted metal species. The similar result was obtained by SLM process also. (b) The stirring speed of 350 rpm was found to be sufficient for minimizing the resistance due to aqueous boundary layer. (c) The cobalt flux increases with increase in pH from 4.00 to 6.00. There was no extraction of cobalt obtained below the feed pH 3.00. But in SX process the distribution coefficient increases with increase in pH from 4.00 to 6.00. Above the pH 6.00 both flux and distribution coefficient decreases. (d) The H2SO4 concentration of 25 mol/m3 provides enough proton to break the metal-Cyanex 272 complex and displace the equilibrium backward for both SLM process and SX process. (e) For removal of cobalt from industrial effluent by SLM process can be more effective than solvent extraction process.
Dr Basudev Swain
Institute for Advanced Engineering (IAE)
Read the Original
This page is a summary of: Extraction of Co(II) by supported liquid membrane and solvent extraction using Cyanex 272 as an extractant: A comparison study, Journal of Membrane Science, February 2007, Elsevier,
DOI: 10.1016/j.memsci.2006.11.012.
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