Countercurrent reverse osmosis for ethanol-water separation. Final report, August 7, 1981-November 6, 1982
The objective of this program was to investigate the technical and economic feasibility of producing concentrated ethanol from dilute feedstocks using a membrane process called countercurrent reverse osmosis (CCRO). A number of commerical membranes prepared in our laboratory for their suitability for CCRO application were evaluated. Included were some of the best RO membranes currently available for desalination. In all cases the membranes exhibited decreasing ethanol-water selectivities with increasing ethanol concentration in the feed stream, becoming essentially non-selective toward a 50- to 60-vol % ethanol feed. Thus, it appears that even with state-of-the-art membranes, concentration of ethanol above 50 vol % is not possible. It was also observed various degrees of degradation among the membranes. To test the feasibility of using CCRO to reduce osmotic pressure across the membranes, experiments were performed in which ethanol solutions were introduced on the permeate side of the membrane. In only one membrane (developed at Bend Research and designated 3N8) was a large effect observed. the results obtained with 3N8 membranes were used as the basis for projecting the performance of the CCRO process. An economic analysis of CCRO was conducted, including a comparison of the economics of CCRO with distillation. The results of this analysis suggest that CCRO is more energy-efficient than distillation for a given product concentration and output rate, but that it involves higher capital equipment costs.
- Research Organization:
- Bend Research, Inc., OR (USA)
- DOE Contract Number:
- FG07-81ID12320
- OSTI ID:
- 6350641
- Report Number(s):
- DOE/ID/12320-T1; ON: DE83009725
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ETHANOL
SEPARATION PROCESSES
MEMBRANES
OSMOSIS
WATER
ALCOHOLS
DIFFUSION
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ORGANIC COMPOUNDS
OXYGEN COMPOUNDS
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