Removal of Chromium(VI) from Industrial Effluents Through Supported Liquid Membrane Using Trioctylphosphine Oxide as a Carrier

The present study describes extraction of chromium(VI) through supported liquid membrane (SLM), Celgard 2400, which was impregnated with trioctylphosphine oxide (TOPO) dissolved in toluene. The stripping phase was comprised of diphenylcarbazide (DPC) in sulfuric acid (H2SO4) whereas the feed phase consists of potassium dichromate (K2Cr2O7) and hydrogen peroxide (H2O2). The effects of concentrations of chromium, TOPO, DPC, and H2SO4 have been studied in order to evaluate the transport efficiency of chromium(VI) ion. The optimum experimental conditions for the chromium(VI) extraction were established as follows: 19.2 x 10(-4) mol L-1 chromium ion, 1.5 mol L-1 H2O2 concentration in the feed phase, 0.1 mol L-1 TOPO concentration in the membrane phase and 0.001 mol L-1 DPC and 1.5 mol L-1 H2SO4 as stripping phase. The measurements of percent recovery, distribution coefficient, flux and permeability were made at the given optimized conditions. The extraction time and membrane stability were also investigated. Extraction efficiency of 80% was recorded in 180 min and the SLM system was found stable up to 10 days. The optimized SLM system was then applied on the paint industry wastewater; about 80% of chromium(VI) was successfully removed from the wastewater.