1 Extraction of Chromium (VI) From Aqueous Solution By Emulsion Liquid Membrane Technique and Optimization of Extraction Process Parameters Using Central Composite Design, Revathi K*, Anuradha S, Karuppaiya M, Vimalashanmugam K and Viruthagiri T
The extraction of Cr (VI) through an Emulsion Liquid Membrane (ELM) was investigated, using Methyl Isobutyl Ketone (MIBK) as mobile carrier. The emulsion liquid membrane phase consists of kerosene as diluent, MIBK as carrier, SPAN-80 as surfactant and NaOH solution as stripping phase. The percentage extraction of chromium (VI) from synthetic solution has been investigated in batch mode experiments. The influence of process parameters namely stripping solution concentration, surfactant concentration, extractant concentration, initial metal ion concentration on the extraction of chromium were examined using central composite design of Response surface methodology. The central composite design in RSM was used for designing the experiments as well as for full response surface estimation. The optimum conditions for maximum percentage extraction of chromium (VI) from the dilute aqueous solution were as follows: stripping solution concentration (0.0575 M), surfactant concentration (3.4586 vol.%), Extractant concentration (3.667 vol.%) and Initial metal ion concentration (479.8 mg/l). The high correlation coefficient (R2 = 0.9676) between the model and the experimental data showed that the model was able to predict the percentage extraction of chromium (VI) from the aqueous solution using ELM efficiently. At the optimized condition the maximum percentage of chromium extraction was found to be 98.1%.