MEMBRANE SOLVENT-EXTRACTION REMOVAL OF PRIORITY ORGANIC POLLUTANTS FROM AQUEOUS WASTE STREAMS

A recently developed nondispersive microporous membrane-based solvent extraction technique has been used to remove a number of priority organic pollutants simultaneously from a synthetic high strength aqueous waste stream. A microporous hydrophobic hollow fiber based membrane extractor having an order of magnitude higher contact area than conventional extraction devices has been used. The pollutants were phenol, 2-chlorophenol, nitrobenzene, toluene, and acrylonitrile. The extracting solvents were methyl isobutyl ketone (MIBK), isopropyl acetate (IPAc), and hexane. The distribution coefficient of each pollutant has been measured for each solvent over a wide concentration range. In the once-through extracting mode, the concentrations of all pollutants in the aqueous phase flowing through the hollow fiber lumen were reduced to less than 20 mg/L using either MIBK or IPAc as solvent flowing countercurrently on the hollow fiber module shell-side. A lumped mass-transfer analysis has been made to characterize the observed mass transfer for all pollutants. This technique was shown to be efficient in cleaning high strength wastewaters containing pollutants, which may be polar, nonpolar, high boiling, low boiling, aromatic, aliphatic, etc.