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Oxidizer Scrubber Solution Recycling by Freeze Crystalliation

Award Information
Agency: Department of Defense
Branch: Air Force
Contract: N/A
Agency Tracking Number: 20055
Amount: $57,273.00
Phase: Phase I
Program: SBIR
Solicitation Topic Code: N/A
Solicitation Number: N/A
Timeline
Solicitation Year: N/A
Award Year: 1993
Award Start Date (Proposal Award Date): N/A
Award End Date (Contract End Date): N/A
Small Business Information
2539-c Noblin Road, P.o. Box 40968
Raleigh, NC 27629
United States
DUNS: N/A
HUBZone Owned: No
Woman Owned: No
Socially and Economically Disadvantaged: No
Principal Investigator
 James A. Heist
 (919) 850-0600
Business Contact
Phone: () -
Research Institution
N/A
Abstract

When loading nitrogen tetroxide before launching the space shuttle, fugitive N2O4 is absorbed into caustic solutions in a two stage scrubber solution. The second stage of the scrubber has sodium sulfite added to the alkaline scrubbing solution to act as an oxidant scavenger, to improve scrubbing efficiency. The N2O4 oxidant reacts with water and with the sulfite to form acids (neutralized by the alkalinity in the solution) and sulfates. The residual caustic concentration makes the spent solution a characteristic hazardous waste. This proposal addresses an approach that uses freeze crystallization to crystallize sodium nitrate and sodium sulfate salts from the spent scrubbing solution, to remove part of the water in the spent solution as pure ice, and thus to concentrate and purify the residual hydroxide alkalinity so that it can be reused in the scrubbing operation. To improve the efficiency in removing the nitrate and sulfate salts, nitrites and sulfites will be oxidized by adding air. Testing here will determine whether this needs to be a pressurized reaction, or if atmospheric conditions are sufficient. The hydroxide can be crystallized from the treating solution if necessary to recover it at higher concentrations or in ultra-high purity.

* Information listed above is at the time of submission. *

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