Facilitated transport of cationic dyes through a supported liquid membrane with D2EHPA as carrier

The transport of cationic dyes methyl violet and rhodamine B from aqueous synthetic dye solution through flat type supported liquid membranes (SLM) using di (2-ethylhexyl) phosphoric acid (D2EHPA) as carrier was studied and the parameters affecting the dyes transport were determined. The extraction was carried out from the aqueous feed phase with pH 4 ± 0.2 to a more acidic strip phase of acetic acid (AcOH) with pH 2.5. The proton gradient between the feed and the strip phase was the main driving force of the mass transfer in this system. The influence of various parameters such as pH of the feed phase, strip phase concentration, carrier concentration, stirring speed and the concentration of dyes on the extraction efficiency was studied. Kinetics of transport was also studied. The optimum conditions of transport are feed phase pH 4 ± 0.2, acetic acid as stripping phase with pH 2.5, stirring speed at 600 rpm. The maximum recovery under optimum conditions was observed as 94.2% for methyl violet and 90.0% for rhodamine B.