EMULSION LIQUID MEMBRANE EXTRACTION OF CHROMIUM(VI) FROM SUPERFUND SITES

CHROMIUM CONTAMINATION IS PRESENT AT OVER ONE-HALF OF THE SUPERFUND SITES. CHROMIUM(VI) IS A STRONG OXIDIZER, TOXIC, CARCINOGENIC, AND IS PARTICULARLY DIFFICULT TO MANAGE BECAUSE CHROMIUM IS USUALLY PRESENT AS AN ANION. IT HAS LITTLE INTERACTION WITH THE SOIL, RESULTING IN WIDESPREAD GROUND-WATER CONTAMINATION, AND IT CANNOT BE TREATED BY CONVENTIONAL PROCESSES WHICH ARE DESIGNED TO REMOVE CATIONS. CONVENTIONAL PROCESSES FOR CHROMIUM REMOVAL (REDUCTION FOLLOWED BY PRECIPITATION) ARE VERY EXPENSIVE FORTHE DILUTE STREAMS TYPICAL OF GROUND-WATER CONTAMINATION. THEREFORE, TDA RESEARCH PROPOSES THE USE OF EMULSION LIQUID MEMBRANES (ELM) TO PRECONCENTRATE CHROMIUM CONTAMINATED WATER, WHICH COULD RESULT FROM PUMP-AND-TREAT, IN SITU SOIL WASHING, FOR ON-SITE EXTRACTION. BY COMBINING BOTH A COMPLEXING AND STRIPPING AGENT IN A SINGLE UNIT OPERATION, ELM IS CAPABLE OF CONCENTRATING CHROMIUM BY A FACTOR OF GREATER THAN 1000. IN PHASE I, TDA RESEARCH WOULD DEVELOP ASUITABLE EMULSION (SOLVENT, COMPLEXING AGENT, SURFACTANT, AND STRIPPING AGENT), CONDUCT EXPERIMENTS TO DEMONSTRATE PROCESS FEASIBILITY, AND CARRY OUT ECONOMIC ANALYSES TO COMPARE TDA RESEARCH'S ELM PROCESS WITH OTHER COMPETING CHROMIUM CONCENTRATION AND/OR REMOVAL PROCESSES.