Extraction performance of chromium (VI) with emulsion liquid membrane by Cyanex 923 as carrier using response surface methodology

Cr (VI) being a toxic and carcinogenic pollutant should be removed from industrial effluents. In the present investigation, Cr (VI) was transported selectively with Cyanex 923 carrier from bulk feed phase to internal stripping phase using emulsion liquid membrane technique. The liquid membrane was prepared by loading with Cyanex 923 as the carrier, Span 80 as the surfactant, kerosene as the solvent and sodium hydroxide as the stripping agent and their effect on the process parameters such as concentration of the surfactant, the ratio of organic phase to internal phase in the membrane and membrane to external phase ratio were studied using Box–Behnken design and response surface method. A quadratic polynomial regression equation was used to analyze the experimental data. The experimental and predicted values were in good agreement. The experimental results showed that chromium ion was extracted within 5 min. The chromium ion concentration was measured using inductively coupled plasma mass spectrometry (ICP-MS).

Research highlights
► Cyanex 923 as a carrier in ELM removes Cr (VI) successfully from synthetic wastewater.
► A second-order polynomial equation was adequate to predict the permeability as the response.
► An R2 value of 0.94 ensures a sufficient adjustment of the model with the experimental data.
► An ongoing removal of Cr (VI) from external phase by time proves good stability of the liquid membrane.