Continuous removal of hexavalent chromium by emulsion liquid membrane in a modified spray column

Spray contactors operating under terrestrial gravity has been conventionally studied for continuous removal of solutes using emulsion liquid membranes. The present work evaluated the mass transfer performance of this process in a rotating spray column in which the emulsion was dispersed under centrifugal force 50–100 times the gravity. Experiments were carried out for removal of hexavalent chromium from an acidic solution (pH 2) using Aliquat 336 as the carrier. Percentage removal of Cr(VI) was higher compared to that obtained in a traditional spray column. The overall volumetric mass transfer coefficient for countercurrent flow of the phases was estimated to vary between 0.031/s and 0.071/s. A simple mathematical model was developed to describe the transport process in the contactor based on the advancing front approach. The simulation results suggested that diffusional resistance within the emulsion globule assumes significance when terrestrial gravity was replaced by centrifugal acceleration.

► Continuous removal of Cr(VI) by ELM studied in a rotating spray column.
► Emulsion dispersed by centrifugal force rather than conventionally used g.
► Removal higher in former dispersion mode than that under terrestrial gravity (g).
► A mass transfer model developed and experimental data analyzed.
► Possible reduction in contactor volume between ∼6–8 times.