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Title: USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE

Abstract

A bench-scale feasibility study on the use of a Wet Air Oxidation (WAO) process to destroy a slurry laden with tetraphenylborate (TPB) compounds has been undertaken. WAO is an aqueous phase process in which soluble and/or insoluble waste constituents are oxidized using oxygen or oxygen in air at elevated temperatures and pressures ranging from 150 C and 1 MPa to 320 C and 22 MPa. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). Test results indicate WAO is a feasible process for destroying TPB, its primary daughter products [triphenylborane (3PB), diphenylborinic acid (2PB), and phenylboronic acid (1PB)], phenol, and most of the biphenyl byproduct. The required conditions are a temperature of 300 C, a reaction time of 3 hours, 1:1 feed slurry dilution with 2M NaOH solution, the addition of CuSO{sub 4}.5H{sub 2}O solution (500 mg/L Cu) as catalyst, and the addition of 2000 mL/L of antifoam. However, for the destruction of TPB, its daughter compounds (3PB, 2PB, and 1PB), and phenol without consideration for biphenyl destruction, less severe conditions (280 C and 1-hour reaction time with similar remaining above conditions) are adequate.

Authors:
; ;
Publication Date:
Research Org.:
SRS
Sponsoring Org.:
USDOE
OSTI Identifier:
902853
Report Number(s):
WSRC-STI-2007-00176
TRN: US0703058
DOE Contract Number:
DE-AC09-96SR18500
Resource Type:
Conference
Resource Relation:
Conference: IT 2007 Conference
Country of Publication:
United States
Language:
English
Subject:
12 MANAGEMENT OF RADIOACTIVE WASTES, AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; ORGANIC BORON COMPOUNDS; WET OXIDATION PROCESSES; DECOMPOSITION; WASTE PROCESSING; FEASIBILITY STUDIES

Citation Formats

Adu-Wusu, K, Daniel McCabe, D, and Bill Wilmarth, B. USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE. United States: N. p., 2007. Web.
Adu-Wusu, K, Daniel McCabe, D, & Bill Wilmarth, B. USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE. United States.
Adu-Wusu, K, Daniel McCabe, D, and Bill Wilmarth, B. Wed . "USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE". United States. doi:. https://www.osti.gov/servlets/purl/902853.
@article{osti_902853,
title = {USING WET AIR OXIDATION TECHNOLOGY TO DESTROY TETRAPHENYLBORATE},
author = {Adu-Wusu, K and Daniel McCabe, D and Bill Wilmarth, B},
abstractNote = {A bench-scale feasibility study on the use of a Wet Air Oxidation (WAO) process to destroy a slurry laden with tetraphenylborate (TPB) compounds has been undertaken. WAO is an aqueous phase process in which soluble and/or insoluble waste constituents are oxidized using oxygen or oxygen in air at elevated temperatures and pressures ranging from 150 C and 1 MPa to 320 C and 22 MPa. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). Test results indicate WAO is a feasible process for destroying TPB, its primary daughter products [triphenylborane (3PB), diphenylborinic acid (2PB), and phenylboronic acid (1PB)], phenol, and most of the biphenyl byproduct. The required conditions are a temperature of 300 C, a reaction time of 3 hours, 1:1 feed slurry dilution with 2M NaOH solution, the addition of CuSO{sub 4}.5H{sub 2}O solution (500 mg/L Cu) as catalyst, and the addition of 2000 mL/L of antifoam. However, for the destruction of TPB, its daughter compounds (3PB, 2PB, and 1PB), and phenol without consideration for biphenyl destruction, less severe conditions (280 C and 1-hour reaction time with similar remaining above conditions) are adequate.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Apr 04 00:00:00 EDT 2007},
month = {Wed Apr 04 00:00:00 EDT 2007}
}

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  • Tank 48H return to service is critical to the processing of high level waste (HLW) at Savannah River Site (SRS). Liquid Waste Disposition (LWD) management has the goal of returning Tank 48H to routine service by January 2010 or as soon as practical. Tank 48H currently holds legacy material containing organic tetraphenylborate (TPB) compounds from the operation of the In-Tank Precipitation process. This material is not compatible with the waste treatment facilities at SRS and must be removed or undergo treatment to destroy the organic compounds before the tank can be returned to Tank Farm service. Tank 48H currently containsmore » {approx}240,000 gallons of alkaline slurry with about 2 wt % potassium and cesium tetraphenylborate (KTPB and CsTPB). The main radioactive component in Tank 48H is {sup 137}Cs. The waste also contains {approx}0.15 wt % Monosodium Titanate (MST) which has adsorbed {sup 90}Sr, U, and Pu isotopes. A System Engineering Evaluation of technologies/ideas for the treatment of TPB identified Wet Air Oxidation (WAO) as a leading alternative technology to the baseline aggregation approach. Over 75 technologies/ideas were evaluated overall. Forty-one technologies/ideas passed the initial screening evaluation. The 41 technologies/ideas were then combined to 16 complete solutions for the disposition of TPB and evaluated in detail. Wet Air Oxidation (WAO) is an aqueous phase process in which soluble or suspended waste components are oxidized using molecular oxygen contained in air. The process operates at elevated temperatures and pressures ranging from 150 to 320 C and 7 to 210 atmospheres, respectively. The products of the reaction are CO{sub 2}, H{sub 2}O, and low molecular weight oxygenated organics (e.g. acetate, oxalate). The basic flow scheme for a typical WAO system is as follows. The waste solution or slurry is pumped through a high-pressure feed pump. An air stream containing sufficient oxygen to meet the oxygen requirements of the waste stream is injected into the pressurized waste stream, and the air/liquid mixture is preheated to the required reactor inlet temperature. The reactor provides sufficient retention time to allow the oxidation to approach the desired level of organic decomposition. Typical reaction time is about 30-120 minutes. Heat exchangers are routinely employed to recover energy contained in the reactor effluent to preheat the waste feed/air entering the reactor. Auxiliary energy, usually steam, is necessary for startup and can provide trim heat if required. Since the oxidation reactions are exothermic, sufficient energy may be released in the reactor to allow the WAO system to operate without any additional heat input. After cooling, the oxidized reactor effluent passes through a pressure control valve where the pressure is reduced. A separator downstream of the pressure control valve allows the depressurized and cooled vapor to separate from the liquid. Typical industrial WAO applications have a feed flow rate of 1 to 220 gallons per minute (gpm) per train, with a chemical oxygen demand (COD) from 10,000 to 150,000 mg/L (higher CODs with dilution). Note that catalysts, such as homogeneous copper and iron, their heterogeneous counterparts, or precious metals can be used to enhance the effectiveness (i.e., to lower temperature, pressure, and residence time as well as increase oxidation efficiencies) of the WAO reaction if deemed necessary.« less
  • Wet Air Oxidation (WAO) is one of the two technologies being considered for the destruction of Tetraphenylborate (TPB) in Tank 48H. Batch bench-scale autoclave testing with radioactive (actual) Tank 48H waste is among the tests required in the WAO Technology Maturation Plan. The goal of the autoclave testing is to validate that the simulant being used for extensive WAO vendor testing adequately represents the Tank 48H waste. The test objective was to demonstrate comparable test results when running simulated waste and real waste under similar test conditions. Specifically: (1) Confirm the TPB destruction efficiency and rate (same reaction times) obtainedmore » from comparable simulant tests, (2) Determine the destruction efficiency of other organics including biphenyl, (3) Identify and quantify the reaction byproducts, and (4) Determine off-gas composition. Batch bench-scale stirred autoclave tests were conducted with simulated and actual Tank 48H wastes at SRNL. Experimental conditions were chosen based on continuous-flow pilot-scale simulant testing performed at Siemens Water Technologies Corporation (SWT) in Rothschild, Wisconsin. The following items were demonstrated as a result of this testing. (1) Tetraphenylborate was destroyed to below detection limits during the 1-hour reaction time at 280 C. Destruction efficiency of TPB was > 99.997%. (2) Other organics (TPB associated compounds), except biphenyl, were destroyed to below their respective detection limits. Biphenyl was partially destroyed in the process, mainly due to its propensity to reside in the vapor phase during the WAO reaction. Biphenyl is expected to be removed in the gas phase during the actual process, which is a continuous-flow system. (3) Reaction byproducts, remnants of MST, and the PUREX sludge, were characterized in this work. Radioactive species, such as Pu, Sr-90 and Cs-137 were quantified in the filtrate and slurry samples. Notably, Cs-137, boron and potassium were shown as soluble as a result of the WAO reaction. (4) Off-gas composition was measured in the resulting gas phase from the reaction. Benzene and hydrogen were formed during the reaction, but they were reasonably low in the off-gas at 0.096 and 0.0063 vol% respectively. Considering the consistency in replicating similar test results with simulated waste and Tank 48H waste under similar test conditions, the results confirm the validity of the simulant for other WAO test conditions.« less
  • Biomass gasification wastewaters (BGW) from Texas Tech University's biomass gasifier were treated using wet air oxidation (WAO), solvent extraction, and reverse osmosis (RO) technologies. These technologies were reviewed to determine if they could be competitive or complimentary to innovative biological technologies studied earlier. Results obtained from experimental studies completed on these three technologies during the past year are reviewed. Wastewaters treated by WAO exhibited chemical oxygen demand (COD) removal percentages ranging from 0% at 5.1 MPa (750 psi) and 150/sup 0/C to 85% removal at 13.8 MPa (2000 psi) and 300/sup 0/C. Oxidation times varied from 20 to 180 minutes,more » although it was determined that the removal of COD became less dependent on reaction time as the severity of treatment conditions was increased. Color removal using WAO ranged from 56 to 99%. Solvent extraction studies indicate that none of the conventional solvents (i.e., methyl isobutyl ketone, n-butyl acetate, n-butanol, kerosene, toluene, tri-butyl phosphate, tri-n-octyl phosphine oxide, and mixtures of these compounds) are effective in the removal of organics; the best distribution coefficient of 1.3 was given by n-butanol. Hence, solvent extraction is probably not an effective treatment technology for BGW. RO studies on biologically treated BGW indicate 99.7 to 99.8% of the initial COD (approx. 7000 mg/l) can be removed from these wastewaters. Essentially total removal of color was also observed.« less
  • Solar energy is being applied to one of the most difficult environmental problems our country faces in the coming decades: the destruction of hazardous waste. DOE Researchers are developing two separate technologies -- solar detoxification of water and solar decontamination of soil -- that could revolutionize the way toxic wastes are removed from the environment. Unlike many remediation techniques in use today, these solar-based processes actually destroy hazardous contaminants; the wastes are not transferred to other media for disposal. Solar detoxification of water uses solar energy to power a reaction that eliminates organic contaminants from polluted surface water and groundwater.more » The process uses a solar-activated photocatalyst, such as titanium dioxide, to break the bonds holding organic compounds together. Researchers are currently working to increase the efficiency and reduce the costs of the process to make it economically competitive with traditional remediation methods. In a related program researchers are investigating the ability of high solar flux (upwards of 300 times the sun's normal intensity) to decontaminate polluted solids such as soils. The solar decontamination of soil is a two-step process: in the first step contaminants are desorbed from the solid either by solar thermal energy or by conventional means (such as heating or vacuum extraction); in the second step the desorbed contaminants are destroyed. The contaminants can be destroyed by using either a high-flux photolytic process or a low-flux process that employs a photocatalyst. SERI's state-of-the-art high-flux solar furnace is home to a large portion of the soil decontamination research. 4 figs.« less
  • The WAO process, based on oxidation of aqueous suspensions or solutions of organic materials with compressed air or oxygen at elevated temperatures (300/sup 0/-600/sup 0/F) and pressures, demonstrated higher energy efficiency for treating relatively dilute industrial wastewaters containing almost any organic materials (except for highly halogenated compounds), as compared with the coventional incineration technology. The WAO treatment produces no NO/sub x/ and SO/sub 2/, and almost no particulate emissions. Even wastes with very low fuel values can be treated by WAO by mixing them with any low-grade nonvolatile fuel, and the energy requirements may be minimized by heat exchange betweenmore » the cold incoming products and the hot offgases. As the fuel value of wastes increases, utilization of the reaction heat makes a WAO unit independent of outside fuel and of outside power (used for pumping and compression), and finally, a net energy producer. A variation of WAO for the primary purpose of generating steam (a ''WAO boiler''), currently under development, is expected to have over 95% thermal efficiency and to be more economical than any existing steam generating system, due to simultaneous disposal of aqueous wastes mixed with the fuel.« less