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Title: Treatment of SRS Tank 48H Simulants Using Fenton's Reagent

Abstract

High-level-waste Tank 48H at the Savannah River Site (SRS) contains about 50,000 lb of tetraphenylborate (TPB), which must be destroyed to return the tank to active service. Laboratory-scale tests were conducted to evaluate the use of Fenton's Reagent (hydrogen peroxide and a metal catalyst) to treat simulants of the Tank 48H waste. Samples of the treated slurry and the off-gas were analyzed to determine the reaction products. Process parameters developed earlier by AEA Technology were used for these tests; namely (for 500 mL of waste simulant), reduce pH to 7.5 with nitric acid, heat to boiling, add hydrogen peroxide at 1 mL/min for 1 h, reduce pH to 3.5, and add the remaining peroxide at 2 mL/min. These parameters were developed to minimize the formation of tarry materials during the early part of the reaction and to minimize the concentration of total organic carbon in the final treated slurry. The treated samples contained low concentrations of total organic carbon (TOC) and no detectable TPB. Tests using a mixture of iron and copper salts as the Fenton's catalyst had a lower TOC concentration in the final treated slurry than did tests that used a copper-only catalyst. TPB is known to hydrolyzemore » to benzene, particularly at high temperature and low pH, and copper is known to increase the rate of hydrolysis. Significant amounts of benzene were present in the off-gas from the tests, especially during the early portion of the treatment, indicating that the hydrolysis reaction was occurring in parallel with the oxidation of the TPB by Fenton's reagent. For the reaction conditions used in these tests, approximately equal fractions of the TPB were converted to benzene and carbon dioxide. Minimizing the formation of benzene is important to SRS personnel; however, this consideration was not addressed in the AEA-recommended parameters, since they did not analyze for benzene in the off-gas. Smaller amounts of carbon monoxide and other organics were also produced. One test used a simulant with much lower concentrations of salts, representing washed sludge, and this test produced much smaller amounts of benzene. The nitrite ions in the simulant were oxidized to nitrate, which would increase the amount of peroxide required to oxidize all of the organic carbon. Oxygen is the primary constituent of the off-gas produced from treatment of the samples.« less

Authors:
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
885838
Report Number(s):
ORNL/TM-2003/262
TRN: US0604104
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
08 HYDROGEN; 12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BENZENE; BOILING; CARBON; CARBON DIOXIDE; CARBON MONOXIDE; CATALYSTS; COPPER; HYDROGEN; HYDROGEN PEROXIDE; HYDROLYSIS; IRON; MIXTURES; NITRIC ACID; NITRITES; OXIDATION; OXYGEN; PEROXIDES; PERSONNEL; TANKS; WASTES

Citation Formats

Taylor, PA. Treatment of SRS Tank 48H Simulants Using Fenton's Reagent. United States: N. p., 2003. Web. doi:10.2172/885838.
Taylor, PA. Treatment of SRS Tank 48H Simulants Using Fenton's Reagent. United States. https://doi.org/10.2172/885838
Taylor, PA. 2003. "Treatment of SRS Tank 48H Simulants Using Fenton's Reagent". United States. https://doi.org/10.2172/885838. https://www.osti.gov/servlets/purl/885838.
@article{osti_885838,
title = {Treatment of SRS Tank 48H Simulants Using Fenton's Reagent},
author = {Taylor, PA},
abstractNote = {High-level-waste Tank 48H at the Savannah River Site (SRS) contains about 50,000 lb of tetraphenylborate (TPB), which must be destroyed to return the tank to active service. Laboratory-scale tests were conducted to evaluate the use of Fenton's Reagent (hydrogen peroxide and a metal catalyst) to treat simulants of the Tank 48H waste. Samples of the treated slurry and the off-gas were analyzed to determine the reaction products. Process parameters developed earlier by AEA Technology were used for these tests; namely (for 500 mL of waste simulant), reduce pH to 7.5 with nitric acid, heat to boiling, add hydrogen peroxide at 1 mL/min for 1 h, reduce pH to 3.5, and add the remaining peroxide at 2 mL/min. These parameters were developed to minimize the formation of tarry materials during the early part of the reaction and to minimize the concentration of total organic carbon in the final treated slurry. The treated samples contained low concentrations of total organic carbon (TOC) and no detectable TPB. Tests using a mixture of iron and copper salts as the Fenton's catalyst had a lower TOC concentration in the final treated slurry than did tests that used a copper-only catalyst. TPB is known to hydrolyze to benzene, particularly at high temperature and low pH, and copper is known to increase the rate of hydrolysis. Significant amounts of benzene were present in the off-gas from the tests, especially during the early portion of the treatment, indicating that the hydrolysis reaction was occurring in parallel with the oxidation of the TPB by Fenton's reagent. For the reaction conditions used in these tests, approximately equal fractions of the TPB were converted to benzene and carbon dioxide. Minimizing the formation of benzene is important to SRS personnel; however, this consideration was not addressed in the AEA-recommended parameters, since they did not analyze for benzene in the off-gas. Smaller amounts of carbon monoxide and other organics were also produced. One test used a simulant with much lower concentrations of salts, representing washed sludge, and this test produced much smaller amounts of benzene. The nitrite ions in the simulant were oxidized to nitrate, which would increase the amount of peroxide required to oxidize all of the organic carbon. Oxygen is the primary constituent of the off-gas produced from treatment of the samples.},
doi = {10.2172/885838},
url = {https://www.osti.gov/biblio/885838}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 18 00:00:00 EST 2003},
month = {Tue Nov 18 00:00:00 EST 2003}
}