Extraction of chromium from dilute aqueous solutions by supported liqiud membranes

Keywords: Alamine 336; supported liquid membrane; extraction of Cr(VI) ; permeation coefficient; acidic solutions. One of the heavy metals, which is called chromium, is in the form of trivalent and heksavalent. Cr(VI) is more poisonous than Cr(III). Choromium compounds containing wastes make poisonous effect for fish and the other aquatic creature. Main sources of the Cr (VI) wastes are leather, metal plating, dye, pigment, ink industries. Since metallic chromium and its compounds are widely used in industry, this metal and its ions have been developed to recover and purify from waste water. Precipitating with chalk and caustic soda is main technique for recovery of the Cr(VI). Liquid membrane processes has been discovered by N.N Li since 1968, it is more important method than traditional separation and recovery methods which is purification and enrichment of metals. Especially, ammonium salts has been widely used for selective separation of chromium by supported liquid membrane process. In this study, the extraction of chromium has been carried out from acidic solutions by a flat-sheet supported liquid membrane using Alamine 336 as carrier. A polymer support (Celgard 2500) has been immersed in a membrane solution, which is consisted of diluent and a carrier (Alamine 336). The polymer support has been placed between a two-compartment test cell. Feed and stripping solutions have been filled into the corresponding compartments. Experimental parameters such as solvent type, feed and stripping mixing speeds, feed solution pH, extractant concentration and strip phase concentration, types of polymer support and extractant have been examined and the optimum conditions have been determined. İn addition to this conditions initially Cr(VI) concentration have been studied in optimum conditions. As a result, we have been examined selectively extraction of Cr(VI) from binary and triple solutions as exeperimental.