Removal and recovery of chromium(VI) ion via tri-n-octyl methylammonium chloride-kerosene polypropylene supported liquid membrane

Abstract

The presence of chromium in the natural water can be toxic to aquatic organism and is one of the major environmental problems. Therefore, the removal and recovery of chromium from industrial wastewater is very crucial to accomplish the standard discharge concentration limit. Supported liquid membrane is one of the processes which combines the extraction and recovery process in one single stage. This paper presents an experimental study on the removal and recovery of chromium ions from acidic aqueous solutions through a flat-sheet supported liquid membrane (FSSLM) system. Through this system, chromium ions were transported from feed phase into stripping phase via Tri-n-octyl-methylammoniumchloride (TOMAC)-kerosene-polypropylene supported liquid membrane (SLM). The liquid membrane phase was prepared by dissolving the corresponding volume of the carrier, TOMAC in organic diluent of kerosene. The stripping agent used was sodium hydroxide (NaOH) solution whereas the membrane support used was commercial Accurel polypropylene membrane with good features of 100 μm thickness, porosity of 72% and effective pore size of 0.10 μm. The chromium ion concentration in the feed and stripping phases as a function of time was analysed using an atomic absorption spectrometry (AAS). The effects of different operational variables such as TOMAC concentration in the membrane phase, NaOH concentration in the stripping phase and pH of the aqueous feed phase were investigated. The result demonstrated that about 90 and 98% of 150 ppm of chromium was removed and recovered, respectively at favorable condition of 1.0 M TOMAC, 0.5 M NaOH and pH 2 of the feed phase.