Thermochemical nitrate reduction

• Main Authors: Cox, J. L., Lilga, M. A., Hallen, R. T.
• Other Authors: United States. Department of Energy.
• Format: Report
• Language: English
• Published: Pacific Northwest Laboratory 1992
• Subjects: Urea; Aldehydes; Chromatography; Formates; Processing; Organic Compounds; Elements; Chemical Reaction Kinetics; Amides; Chemical Reactions; Numerical Data; Data; Monosaccharides; Hydrogen Compounds; Separation Processes; Kinetics; Methane; 12 Management Of Radioactive And Non-Radioactive Wastes From Nuclear Facilities; Nitrogen Compounds; Oxygen Compounds; Carboxylic Acid Salts; Hydrocarbons; Gas Chromatography; Hydrides; Nitrates; Reducing Agents; Waste Processing 052001* > Nuclear Fuels > Waste Processing; Reaction Kinetics; Ammonia; Denitration; Experimental Data; Temperature Range; Information; Thermochemical Processes; Hydrogen; Chemical Reactors; Management; Radioactive Waste Management; Carbonic Acid Derivatives; Temperature Range 0400-1000 K; Carbohydrates; Radioactive Waste Processing; Waste Management; Organic Nitrogen Compounds; Nonmetals; Glucose; Reduction; Hexoses; Saccharides; Alkanes; Nitrogen Hydrides; Carbonic acid
• Online Access: https://doi.org/10.2172/7077253; https://digital.library.unt.edu/ark:/67531/metadc1196345/

A series of preliminary experiments was conducted directed at thermochemically converting nitrate to nitrogen and water. Nitrates are a major constituent of the waste stored in the underground tanks on the Hanford Site, and the characteristics and effects of nitrate compounds on stabilization techniques must be considered before permanent disposal operations begin. For the thermochemical reduction experiments, six reducing agents (ammonia, formate, urea, glucose, methane, and hydrogen) were mixed separately with {approximately}3 wt% NO{sub 3}{sup {minus}} solutions in a buffered aqueous solution at high pH (13); ammonia and formate were also mixed at low pH (4). Reactions were conducted in an aqueous solution in a batch reactor at temperatures of 200{degrees}C to 350{degrees}C and pressures of 600 to 2800 psig. Both gas and liquid samples were analyzed. The specific components analyzed were nitrate, nitrite, nitrous oxide, nitrogen, and ammonia. Results of experimental runs showed the following order of nitrate reduction of the six reducing agents in basic solution: formate > glucose > urea > hydrogen > ammonia {approx} methane. Airnmonia was more effective under acidic conditions than basic conditions. Formate was also effective under acidic conditions. A more thorough, fundamental study appears warranted to provide additional data on the mechanism of nitrate reduction. Furthermore, an expanded data base and engineering feasibility study could be used to evaluate conversion conditions for promising reducing agents in more detail and identify new reducing agents with improved performance characteristics.