Industrialized nations face a critical problem in replacing the sources of liquid fuels that traditionally have been supplied by petroleum. One solution that has gained increasing support in this country is the use of ethanol produced by fermentation of renewable biomass as an extender in, or supplement to, gasoline for transportation fuel. Distillation, the present method of separating ethanol from the fermentation broth, is an energy-intensive one and frequently uses more energy than is available from the ethanol recovered. There are many investigations under way to find alternative, less energy-intensive techniques for the ethanol-water separation. The separations method described in this article involves the use of solid materials to preferentially remove ethanol from fermentation broths. Subsequent stripping of the ethanol from the sorbent with a dry gas reduces dramatically the energy required for the separation. Three solid sorbents have been investigated experimentally. Their sorption/desorption characteristics are described, and their incorporation in an ethanol recovery process is evaluated. Three sorbents were investigated: two commercially available divinylbenzene crosslinked polystyrene resins in bead form (one with a nominal surface area of 300 m(2)/g, the other with 750 m(2)/g) and an experimental proprietary molecular sieve with hydrophobic properties. Equilibrium adsorption isotherms for two of the sorbents were obtained at ambient temperature (21 degrees C) for ethanol-water solutions containing up to 12 wt. % ethanol. In addition, 40 degrees C isotherms were obtained for the polystyrene sorbents. Although different, the equilibrium isotherms for the sorbents indicated that ethanol could be preferentially sorbed from a dilute solution. Column breakthrough curves indicated very favorable kinetics. Desorption of the ethanol was readily effected with warm (60-80 degrees C), dry nitrogen.

The development, selection, and implementation of technologies to be used in removing cesium from radioactive liquid wastes in preparation for their final disposition is discussed. The methodology involved testing several proposed sorbents in ion‐exchange columns using actual liquid wastes from underground storage tanks at U.S. Department of Energy sites. The sorbents initially tested included resorcinolformaldehyde resin (RF), CS‐100 resin, SuperLig 644C resin, 3M WEB with embedded SuperLig 644, granular potassium cobalt hexacyanoferrate, and granular crystalline silicotitanates (CSTs). The results of the bench‐scale testing were used to select the sorbent for the full‐scale Cesium Removal Demonstration Project (CsRD). This project will treat up to 25,000 gal of radioactive supernatant stored in the Melton Valley Storage Tanks (MVSTs) at Oak Ridge National Laboratory (ORNL). The demonstration system is modular in design and will process supernatant at flows up to 5 gal/min through 12‐in.‐diam columns. Following the demonstration the system will be used for routine processing of tank waste at ORNL. To show their applicability to wastes at other sites, RF and CST sorbents were tested in a bench‐scale column using a diluted Hanford supernatant liquor (double‐shell slurry feed) from tank 241‐AW‐101. The results are compared with those from tests of MVST supernatant.

No abstract