CN105931692A

CN105931692A - Method for stabilizing U(IV) valence state in TBP

Info

Publication number: CN105931692A
Application number: CN201610244630.2A
Authority: CN
Inventors: 左臣; 晏太红; 郑卫芳; 石四维
Original assignee: China Institute of Atomic of Energy
Current assignee: China Institute of Atomic of Energy
Priority date: 2016-04-19
Filing date: 2016-04-19
Publication date: 2016-09-07

Abstract

The invention belongs to the technical field of after treatment of nuclear fuels, and discloses a method for stabilizing a U(IV) valence state in TBP. The method is implemented by introducing acetaldoxime into an organic phase of TBP; or introducing the acetaldoxime into a water phase, and then extracting the acetaldoxime into the organic phase of the TBP by a way of extraction, wherein the concentration of the acetaldoxime introduced into the organic phase of the TBP is 2-100mmol/L, and the concentration of the acetaldoxime introduced into the water phase is 20-1000mmol/L. The method has the advantages of being simple, and being capable of enabling the stabilization time of the U(IV) valence state in the TBP to be long.

Description

A kind of method stablizing U in TBP (IV) valence state

Technical field

The invention belongs to nuclear fuel reprocessing technical field, be specifically related to one and stablize U in TBP (IV) valence state Method.

Background technology

In post processing Purex flow, generally using U (IV) is the Pu (IV) that reducing agent will easily be extracted by TBP Revert to the Pu (III) of difficult extraction, but U (IV) can be gradually by the nitric acid in feed liquid and nitrite-oxidizing one-tenth U (VI), wherein the Oxidation of nitrous acid is especially apparent, and this can accelerate mainly due to nitrous acid in self-catalysis The oxidation of U (IV).U (IV) is oxidized to U (VI) can cause the increase of U (IV) amount of reagent, simultaneously U (IV) The increase of usage amount also can reduce in plutonium except the effect of uranium.In order to solve this problem, traditional way is to use Hydrazine removes nitrous acid as holding reductant, with stable U (IV) valence state, but there is problems in that U (IV) can Partial extraction is in TBP, and nitrous acid relatively U (IV) is easily extracted in TBP, but hydrazine is difficult to be extracted by TBP, Therefore hydrazine is as U (IV) valence state can only stablized during holding reductant in aqueous phase, and the U (IV) in organic facies is easy Be extracted in TBP is nitrite-oxidizing.

In presently disclosed document, also not about how stablizing the report of U (IV) valence state in TBP extractant, Therefore, it is badly in need of a kind of method solving this problem.

Summary of the invention

(1) goal of the invention

According to the problem existing for prior art, the invention provides a kind of method and simply and can make in TBP The method of U (IV) valence stability time length.

(2) technical scheme

In order to solve the problem existing for prior art, the technical scheme that the present invention provides is as follows:

A kind of method stablizing U in TBP (IV) valence state, the method belongs to nuclear fuel reprocessing technical field, closes Key is, the method is introducing aldoxime in TBP organic facies；Or in aqueous phase, introduce aldoxime, then By the way of extraction, aldoxime is extracted in TBP organic facies；

The concentration of the aldoxime wherein introduced in TBP organic facies is 2～100mmol/L；Introduce in aqueous phase The concentration of aldoxime be 20～1000mmol/L.

Preferably, the method is introducing aldoxime in TBP organic facies, and wherein the concentration of aldoxime is 2～100mmol/L.

Preferably, the method is carried out under the conditions of 5～40 DEG C.

(3) beneficial effect

The method of U (IV) valence stability in TBP in the post processing flow process that the present invention provides, the method by In TBP organic facies introduce aldoxime or in aqueous phase introduce aldoxime reach remove nitrous acid purpose.Pass through Measure the absorption photometric value of U (IV), learn that the method can make U (IV) the valence stability time reach more than 5 hours. Its principle is:

In nitric acid medium, under 20 DEG C of temperature conditionss as a example by, the reaction rate constant of aldoxime and nitrous acid For k=(921.6 ± 7.4) (mol/L)^-1 _. ⁵·min^-1；And aldoxime can extract in organic facies TBP on a small quantity, if directly Being added by aldoxime in organic facies, aldoxime also has certain dissolubility in TBP, with nitrous acid in organic facies Reaction.

Accompanying drawing explanation

Fig. 1 be without aldoxime in the presence of, in TBP extractant, U (IV) absorbance changes over figure；

Fig. 2 is under aldoxime existence condition, and in TBP extractant, U (IV) absorbance changes over figure.

Detailed description of the invention

Below in conjunction with Figure of description and specific embodiment, the present invention is further elaborated.

Embodiment 1

With two parts of TBP-xylene solutions containing TBP volume fraction 10% by comparing 1:1 respectively abstraction purification after U (IV) solution (uranium total concentration 3.09g/L, wherein U (IV) concentration 3.07g/L, purity >=99.2%, nitric acid Concentration is 1mol/L), it is divided into two groups, and all under the conditions of 25 DEG C, the aqueous phase of one of which adds concentration For the aldoxime of 20mmol/L, another group aqueous phase does not contains aldoxime.Organic facies, Mei Geyi is taken out after extraction Mensuration of fixing time organic facies, at 450～700nm interval absorbances, can pass through the U (IV) feature in this region Absworption peak investigates the valence stability of U (IV).

Experimental result as shown in Figure 1, 2, from result above, when depositing without aldoxime, after 2 hours, has The peak value of machine middle U (IV) mutually has occurred substantially reducing, i.e. U (IV) there occurs oxidation；And in the presence of aldoxime, Through 5 hours, the peak value of U (IV) was the most more stable.Can significantly improve organic so adding aldoxime in Shi Yan The stability of mutually middle U (IV).

Water In The Experiment phase aldoxime concentration is the lowest, only 20mmol/L, and the aldoxime being extracted into organic facies is less, As improved organic facies aldoxime concentration, the stabilization time of U (IV) valence state, therefore aldoxime was applicable to surely by longer Determine the valence state of U in TBP (IV).

Embodiment 2

As different from Example 1, in addition aldoxime to organic facies, concentration is 2mmol/L.This embodiment Temperature conditions be 40 DEG C.

Embodiment 3

As different from Example 1, in addition aldoxime to organic facies, concentration is 50mmol/L.This embodiment Temperature conditions be 5 DEG C.

Embodiment 4

As different from Example 1, in addition aldoxime to organic facies, concentration is 100mmol/L.

Embodiment 5

As different from Example 1, in addition aldoxime to aqueous phase, concentration is 100mmol/L.

Embodiment 6

As different from Example 1, in addition aldoxime to aqueous phase, concentration is 500mmol/L.

Embodiment 7

As different from Example 1, in addition aldoxime to aqueous phase, concentration is 1000mmol/L.

Claims

1. the method stablizing U in TBP (IV) valence state, it is characterised in that the method is located after belonging to nuclear fuel Reason technical field, the method is introducing aldoxime in TBP organic facies；Or in aqueous phase, introduce aldoxime, By the way of extraction, aldoxime is extracted in TBP organic facies again；

One the most according to claim 1 stablizes the method for U in TBP (IV) valence state, it is characterised in that The method is introducing aldoxime in TBP organic facies, and wherein the concentration of aldoxime is 2～100mmol/L.

One the most according to claim 1 stablizes the method for U in TBP (IV) valence state, it is characterised in that The method is carried out under the conditions of 5～40 DEG C.