PROPERTIES AND CLEANUP OF DEGRADED TRIBUTYL PHOSPHATE-AMSCO SOLUTIONS AND THE RELATIVE STABILITIES OF ALTERNATIVE EXTRACTANT-DILUENT SYSTEMS

Technical Report · Wed Dec 11 00:00:00 EST 1963

DOI:https://doi.org/10.2172/4018547· OSTI ID:4018547

Blake, Jr., C. A.; Davis, W. Jr.; Schmitt, J. M.

The formation and chemical properties of the major degradation products of several diluents in contact with acid nitrate solutions have been studied, together with (1) methods for purifying degraded diluents, (2) methods of pretreating the diluent to minimize degradation, and (3) the relative stability of several extractant-diluent systems. Emphasis was on Amsco 125-82, a specially treated naphtha used extensively at ORNL as a diluent for tributyl phosphate, a prominent extractant in liquid-liquid extraction systems used to recover uranium from aqueous solutions containing many elements. Accelerated degradation of the diluent, usually containing 1 M tributyl phosphate (TBP), was induced by boiling with nitric acid or by irradiating (/sup 60/Co gamma rays) while agitating the solvent phase with nitric acid. Nitroparaffins, RNO/sub 2/, were the major degradation products and were formed at twice the rate when TBP was present during degradation. Under the conditions of degradation, a 100-whr/liter exposure was practically equivalent to 11 hr of boiling with 2 M HNO/sub 3/, as shown by Zr-Nb/sup 95/ extraction, total organic nitrogen analysis, and spectrophotometric analysis. Extraction from acid solution of certain fission products, for example, Zr-Nb but not ruthenium, increased markedly after the degraded solvent had been treated with alkaline reagents, and a test employing solid calcium hydroxide was developed to estimate the extent of diluent degradation. The alkaline treatment converted a significant fraction of the nitroparaffin to the enol form. There was synergistic extraction of Zr-Nb/sup 95/ by the combination of TBP and degraded diluent. The degraded diluents can be cleaned up by scrubbing with alkanolamines to remove nitroparaffin-amine salts or by contacting with activated alumina. Both methods have doubtful economy, and the latter requires solids handling. Low-pressure flash distillation is an effective, inexpensive method for partial or total repurification of degraded TBP- Amsco mixtures. Pretreatlng Amsco 125-82 by scrubbing with concentrated sulfuric acid before degrading with hot nitric acid improved its stability. The stabilities of a number of alternatlve aliphatic and aromatlc diluents were determined. With aliphatic diluents, the configuration most stable against nitration is the simplest, for example, n-dodecane. Aromatic diluents increase the radiation stability and extraction selectivity or TBP. The stabilities of the simple alkylbenzenes against nitration vary widely with the number of alkyl groups, their type and their position, but a mixture of diethylbenzenes low in the para isomer, and some of the polymethylbenzenes, did not form fission product extractants in routine tests. Also, nitration of the benzene ring does not produce extractants for Zr-Nb/sup 95/. (auth)

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• DOE Contract Number: W-7405-ENG-26
• NSA Number: NSA-18-020100
• OSTI ID: 4018547
• Report Number(s): ORNL-3524; CONF-491-1
• Resource Relation: Other Information: From Solvent Extraction Chemistry Symposium, Gatlinburg, Tenn., Oct. 1962. Orig. Receipt Date: 31-DEC-64
• Country of Publication: United States
• Language: English

Related Subjects

CHEMISTRY
ALKANES
ALKYL RADICALS
ALUMINUM OXIDES
AMINES
AMSCO
AROMATICS
BENZENE
BOILING
BUTYL PHOSPHATES
CALCIUM HYDROXIDES
CHEMICAL REACTIONS
COBALT 60
DECOMPOSITION
DISTILLATION
DODECANE
ETHYL RADICALS
FISSION PRODUCTS
GAMMA RADIATION
HYDROXIDES
IMPURITIES
IRRADIATION
ISOMERS
METHYL RADICALS
NIOBIUM 95
NITRIC ACID
OAK RIDGE NATIONAL LABORATORY
ORGANIC NITROGEN COMPOUNDS
POLYMERS
SOLUTIONS
SOLVENT EXTRACTION
STABILITY
SULFURIC ACID
SYNERGISM
URANIUM
WATER
ZIRCONIUM 95