Uranium(VI) extraction by liquid surfactant membrane with N-alkylcaprolactams as a carrier

Extraction of anionic dye from aqueous solutions by emulsion liquid membrane

“…After a surfactant concentration of 4% (w/w), the extraction slightly decreased. Excessive surfactant tends to increase the resistance at the interface and this can be attributed to a number of possible factors caused by high interfacial occupancy of the surfactant that includes decrease in CR extraction at the membrane phase-feed phase interface, increase in interfacial viscosity and decrease in movement of inner droplets within the emulsion globule [9]. Hence, in order to obtain better overall mass transfer, it was decided to maintain 4% (w/w) surfactant concentration in all other experiments.…”

Selective extraction of chromium (VI) from multicomponent acidic solutions by emulsion liquid membranes using tributhylphosphate as carrier

“…At higher surfactant concentration (beyond 4%), although the membrane stability increases, mass transfer resistance also increases due to presence of more surfactant at aqueous-organic phase interface, resulting in less transfer of chromium (VI) molecules to internal phase. As Span 80 concentration increases, the decrease in the rates of extraction could be attributed to a number of possible factors caused by high interfacial occupancy of the surfactant that includes decrease in rate of cadmium iodide complexation at the membrane phase-feed phase interface, increase in interfacial viscosity and decrease in movement of inner droplets within the emulsion globule and so on [41]. With 3% (wt%) Span 80, although the extraction rate was higher than in the other cases in the first 4 min, the emulsion was less stable under the experimental conditions.…”

Extraction of cadmium from solutions containing various heavy metal ions by Amberlite LA-2

“…A similar effect was observed by Reis and Carvalho [35] and Valenzuela et al [36] in the recovery of zinc and copper ions. As Span 80 concentration increases, the decrease in the rates of extraction could be attributed to a number of possible factors caused by high interfacial occupancy of the surfactant that includes decrease in rate of cadmium iodide complexation at the membrane phasefeed phase interface, increase in interfacial viscosity and decrease in movement of inner droplets within the emulsion globule and so on [37]. With 4% Span 80, although the extraction rate was higher than in the other cases in the first 2 min, the emulsion was less stable under the experimental conditions.…”