HOLLOW-FIBER SOLVENT-EXTRACTION REMOVAL OF TOXIC HEAVY-METALS FROM AQUEOUS WASTE STREAMS

This study is concerned with the applications of the immobilized inter face-based techinques to reversible chemical complexation-based solven t extraction of toxic heavy metals from industrial wastewaters using m icroporous hydrophobic hollow fiber (MHF) modules. Toxic heavy metals studied were copper and chromium(VI). Each metal was individually remo ved in separate once-through experiments from a synthetic wastewater b y organic extractants flowing in the shell-side countercurrent to wast ewater flowing in the fiber bore. The organic extractant used for copp er extraction was 5-20 % v/v LIX 84 diluted in n-heptane, and that for chromium extraction was 30 % v/v TOA (tri-n-octylamine) diluted in xy lene. A mathematical model was developed to predict the extent of copp er extraction from the aqueous synthetic wastewater by the MHF module. The equilibrium constant for copper was determined to be 1.7 from exp erimental partitioning data. The experimental data on copper extractio n in the MHF module are described well by the model if the forward int erfacial chemical reaction rate constant is 9.0 x 10(-6) cm/s.