阅读说明：本技术 一种含钆二氧化铀中氧化钆含量的edta滴定检测方法 (EDTA titration detection method for content of gadolinium oxide in gadolinium-containing uranium dioxide ) 是由 申亚男 张庆明 纪秋宇 韩凤娇 李清超 安宁 于 2020-11-26 设计创作，主要内容包括：本发明属于化学检测技术领域,具体涉及一种含钆二氧化铀中氧化钆含量的EDTA滴定检测方法,包括步骤一、样品的制备与称量,步骤二、样品的溶解,步骤三、铀的分离,步骤四、酸度的控制及溶液滴定,步骤五、Fe～(3+)干扰的消除,步骤六、计算结果；本方法通过称样量的选择、样品的溶解实验、铀的分离实验、酸度的控制和缓冲溶液的加入量的选择、实验比对等,以1.0g含钆二氧化铀试样计,方法精密度优于1％。方法准确可靠,满足该项目分析技术指标要求。本方法大幅度提高检测结果的精密度,过程相对简单,准确性、精密度都能满足实验需求。(The invention belongs to the technical field of chemical detection, and particularly relates to an EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide 3+ Eliminating interference, and calculating a result; according to the method, through the selection of the sample weighing amount, the dissolution experiment of the sample, the separation experiment of uranium, the control of acidity, the selection of the addition amount of the buffer solution and the equivalence of the experiment ratio, the method precision is superior to 1% based on 1.0g of the gadolinium-containing uranium dioxide sample. The method is accurate and reliable, and meets the technical index requirements of the project analysis. The method greatly improves the precision of the detection result, has relatively simple process, and can meet the experiment requirements on accuracy and precision.)

1. An EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide comprises the steps of preparing and weighing a sample, dissolving the sample, separating uranium, controlling acidity and titrating the solution, and performing Fe titration³⁺Eliminating interference, and calculating a result;

the method is characterized in that:

step one, preparing and weighing a sample;

grinding and sieving the gadolinium-containing uranium dioxide pellets to obtain pellets with the particle size of less than 154 mu m, storing the pellets in a dry and clean polyethylene bottle, and weighing the pellets to obtain 1.0g of pellets, wherein the weight of the pellets is accurate to 0.0001 g;

step two, dissolving a sample;

dissolving a sample by using a hydrochloric acid (1+1) solution;

when 10mL of hydrochloric acid (1+1) is added, the sample is completely dissolved, the solution is bright yellow, the uranium is completely converted into uranyl nitrate, the solution is continuously heated, the temperature is controlled to be 200-250 ℃, the solution is heated and evaporated until the solution is 1-1.5 mL, the solution is taken down, and then the solution is cooled to the room temperature;

step three, separating uranium;

separating and removing uranium by taking TBP as an extracting agent, selecting dimethylbenzene as a diluent, and mixing the components according to the mass ratio of TBP: xylene ═ 1: 3, mixing in a nitric acid system at a ratio of 5.0-5.5 mol/L; v_{Water (W)}：V_{Is provided with}According to the following steps: 2, extracting twice according to 1g of weighed sample amount to separate out 99.99 percent of uranium;

step four, controlling acidity and titrating solution;

controlling the acidity to be 5-6, and selecting hydrochloric acid-hexamethylenetetramine as a buffer solution, wherein the volume of the buffer solution is 5 mL; adding 1 drop of methyl orange indicator into a conical flask, adjusting the solution to turn yellow by using ammonia water and hydrochloric acid, and adding 5mL of hexamethylenetetramine buffer solution; adding 2 drops of xylenol orange indicator, and titrating with EDTA until the solution turns from red to yellow, namely the titration end point;

step five, Fe³⁺Interference cancellation

If the sample contains Fe³⁺Adding ascorbic acid to the mixture to obtain Fe³⁺After reduction, aminosalicylic acid is added to mask the reaction product;

step six, calculating results

The content of gadolinium oxide in the sample is calculated by the following formula (1) in terms of mass fraction W in percent (%):

in the formula:

w is the mass fraction of gadolinium oxide in the sample, and the unit is percentage (%);

C_EDTA-the calibrated EDTA concentration in moles per liter (mol/L);

V_EDTAconsumption of EDTA volume in milliliters (mL)

m-weight of sample (g);

0.8674-mass fraction of gadolinium in gadolinium oxide;

and the calculation result retains the last two digits of the decimal point.

2. The EDTA titration detection method of gadolinium oxide content in gadolinium-containing uranium dioxide of claim 1, wherein: in the second step, the heating temperature of the electric heating plate is 200 ℃.

3. The EDTA titration detection method of gadolinium oxide content in gadolinium-containing uranium dioxide of claim 1, wherein: in the second step, 5mL of hydrochloric acid solution is added.

4. The EDTA titration detection method of gadolinium oxide content in gadolinium-containing uranium dioxide of claim 1, wherein: and step three, the TBP is in the range of 29-31%.

5. The EDTA titration detection method of gadolinium oxide content in gadolinium-containing uranium dioxide of claim 1, wherein: and step three, transferring the dissolved solution into a separating funnel containing 10mL of the extracting agent by using a 5.5mol/L nitric acid solution.

6. The EDTA titration detection method of gadolinium oxide content in gadolinium-containing uranium dioxide of claim 1, wherein: step five, when the sample contains Fe³⁺The content is more than 0.02%, ascorbic acid is added into the conical flask, and then aminosalicylic acid is added.

7. The EDTA titration method for detecting the content of gadolinium oxide in gadolinium-containing uranium dioxide according to any one of claims 1 to 6, wherein: the gadolinium oxide content in the gadolinium-uranium dioxide is 8 +/-1%.

Technical Field

The invention belongs to the technical field of chemical detection, and particularly relates to an EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide.

Background

The gadolinium-containing uranium dioxide is widely applied to nuclear products as a new nuclear fuel, at present, only an X fluorescence method is inquired in domestic literature about determination of the content of gadolinium oxide in the gadolinium-containing uranium dioxide, no relevant chemical detection method is found, even a few literature about chemical analysis methods of gadolinium element are referred to, and finally an EDTA titration detection method for the content of gadolinium oxide in the gadolinium-containing uranium dioxide is established through research of a large number of condition experiments.

In the measurement of gadolinium oxide, analysis methods such as atomic absorption spectrometry, atomic emission spectrometry, inductively coupled plasma mass spectrometry, and the like are generally used depending on the level of gadolinium in a sample and the properties of the sample.

The instrumental analysis method generally has higher detection precision on low-content elements, and the detection precision of a constant analysis method cannot meet the detection precision requirement; the instrument analysis method has small sample weighing amount and relatively poor representativeness, results have large errors, and the precision manufacturing requirements of the existing uranium dioxide nuclear fuel cannot be met.

Disclosure of Invention

Aiming at the defects, the invention aims to provide an EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide, and the EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide is established, wherein the content of gadolinium oxide is 5% -10% from the determined range, and the requirements of scientific research and production detection are met.

The technical scheme of the invention is as follows:

an EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide comprises the steps of preparing and weighing a sample, dissolving the sample, separating uranium, controlling acidity and titrating the solution, and performing Fe titration³⁺Eliminating interference, and calculating a result;

step one, preparing and weighing a sample;

grinding and sieving the gadolinium-containing uranium dioxide pellets to obtain pellets with the particle size of less than 154 mu m, storing the pellets in a dry and clean polyethylene bottle, and weighing the pellets to obtain 1.0g of pellets, wherein the weight of the pellets is accurate to 0.0001 g;

step two, dissolving a sample;

dissolving a sample by using a hydrochloric acid (1+1) solution;

when 10mL of hydrochloric acid (1+1) is added, the sample is completely dissolved, the solution is bright yellow, the uranium is completely converted into uranyl nitrate, the solution is continuously heated, the temperature is controlled to be 200-250 ℃, the solution is heated and evaporated until the solution is 1-1.5 mL, the solution is taken down, and then the solution is cooled to the room temperature;

step three, separating uranium;

separating and removing uranium by taking TBP as an extracting agent, selecting dimethylbenzene as a diluent, and mixing the components according to the mass ratio of TBP: xylene ═ 1: 3, mixing in a nitric acid system at a ratio of 5.0-5.5 mol/L; v_{Water (W)}：V_{Is provided with}According to the following steps: 2, extracting twice according to 1g of weighed sample amount to separate out 99.99 percent of uranium;

step four, controlling acidity and titrating solution;

controlling the acidity to be 5-6, and selecting hydrochloric acid-hexamethylenetetramine as a buffer solution, wherein the volume of the buffer solution is 5 mL; adding 1 drop of methyl orange indicator into a conical flask, adjusting the solution to turn yellow by using ammonia water and hydrochloric acid, and adding 5mL of hexamethylenetetramine buffer solution; adding 2 drops of xylenol orange indicator, and titrating with EDTA until the solution turns from red to yellow, namely the titration end point;

step five, Fe³⁺Interference cancellation

If the sample contains Fe³⁺Adding ascorbic acid to the mixture to obtain Fe³⁺After reduction, aminosalicylic acid is added to mask the reaction product;

step six, calculating results

The content of gadolinium oxide in the sample is calculated by the following formula (1) in terms of mass fraction W in percent (%):

in the formula:

w is the mass fraction of gadolinium oxide in the sample, and the unit is percentage (%);

C_EDTA-signThe determined EDTA concentration is expressed in units of moles per liter (mol/L);

V_EDTAconsumption of EDTA volume in milliliters (mL)

m-weight of sample (g);

0.8674-mass fraction of gadolinium in gadolinium oxide;

and the calculation result retains the last two digits of the decimal point.

In the second step, the heating temperature of the electric heating plate is 200 ℃.

In the second step, 5mL of hydrochloric acid solution is added.

And step three, the TBP is in the range of 29-31%.

And step three, transferring the dissolved solution into a separating funnel containing 10mL of the extracting agent by using a 5.5mol/L nitric acid solution.

Step five, when the sample contains Fe³⁺The content is more than 0.02%, ascorbic acid is added into the conical flask, and then aminosalicylic acid is added.

The gadolinium oxide content in the gadolinium-uranium dioxide is 8 +/-1%.

The invention has the beneficial effects that:

the EDTA titration detection method for the content of the gadolinium oxide in the gadolinium-containing uranium dioxide is successfully established, the content of the gadolinium oxide in the gadolinium-containing uranium dioxide can be accurately determined by using the experimental conditions listed in the invention, accurate detection data are reported, and the special production is effectively matched.

According to the method, through the selection of the sample weighing amount, the dissolution experiment of the sample, the separation experiment of uranium, the control of acidity, the selection of the addition amount of the buffer solution and the equivalence of the experiment ratio, the method precision is superior to 1% based on 1.0g of the gadolinium-containing uranium dioxide sample. The method is accurate and reliable, and meets the technical index requirements of the project analysis.

The method greatly improves the precision of the detection result, has relatively simple process, and can meet the experiment requirements on accuracy and precision.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

An EDTA titration detection method for the content of gadolinium oxide in gadolinium-containing uranium dioxide comprises the following steps:

step one, preparation and weighing of samples

Grinding and sieving the gadolinium-containing uranium dioxide pellets to obtain pellets with the particle size of less than 154 mu m, storing the pellets in a dry and clean polyethylene bottle, and weighing the pellets to obtain 1.0g of pellets, wherein the weight of the pellets is accurate to 0.0001 g;

the content of gadolinium oxide in gadolinium-containing uranium dioxide is 8 +/-1%, the method belongs to constant analysis, the sample weighing is not too small, the sample weighing is representative and cannot be too large, the dissolution speed is slow when the sample weighing is large, the dissolution difficulty is increased, the uranium separation process is complicated due to the high uranium matrix content in the large sample weighing, the risk of solution loss is increased in the process, and the accuracy of a detection result is influenced.

Step two, sample dissolution

The uranium and the gadolinium are dissolved in both nitric acid and hydrochloric acid, the reaction speed of dissolving in the hydrochloric acid (1+1) solution is high, and the dissolution is complete, and the method adopts the hydrochloric acid (1+1) solution to dissolve a sample.

When 10mL of hydrochloric acid (1+1) is added, the sample is completely dissolved, the solution is bright yellow, the uranium is completely converted into uranyl nitrate, the solution is continuously heated, the temperature is controlled to be 200-250 ℃, the solution is heated and evaporated until the solution is 1-1.5 mL, and then the solution is taken down and cooled to the room temperature. If the volume of the test solution is too much, the acidity is increased, and the separation of uranium at the later stage is not facilitated.

Step three, separating uranium

The metal uranium in the gadolinium-containing uranium dioxide sample and EDTA can also generate a complex reaction, and if the gadolinium-containing uranium dioxide sample is directly titrated, the judgment of the titration end point color is not facilitated, and the detection result is low. The method adopts TBP as an extracting agent to separate and remove uranium, and has uranium extraction effect when the TBP is 29-31 percentOptimally, dimethylbenzene is selected as a diluent, and the mass ratio of the dimethylbenzene to the TBP: xylene ═ 1: 3, and when a nitric acid system is 5.0-5.5 mol/L, the extraction rate of uranium can reach more than 98%. V_{Water (W)}：V_{Is provided with}According to the following steps: 2, extracting twice according to the weight of 1g to separate out 99.99 percent of uranium.

Step four, controlling acidity and titrating solution

In the reaction conditions of the method, the acidity is controlled to be pH 5-6, hydrochloric acid-hexamethylenetetramine is selected as a buffer solution, and the volume of the buffer solution is 5 mL; adding 1 drop of methyl orange indicator into a conical flask, adjusting the solution to turn yellow by using ammonia water and hydrochloric acid, and adding 5mL of hexamethylenetetramine buffer solution; 2 drops of xylenol orange indicator are added and titrated with EDTA until the solution changes from red to yellow, the titration endpoint.

The gadolinium and EDTA react at a pH value of 5-6, the complexation is complete, in order to control the acidity within a proper range, hexamethylenetetramine hydrochloride is selected as a buffer solution, and when 5mL of the buffer solution is added, the recovery rate is 95% -110%.

Step five, Fe³⁺Interference cancellation

If the sample contains Fe³⁺Adding ascorbic acid to the mixture to obtain Fe³⁺After reduction, aminosalicylic acid is added to mask the Fe, and the aminosalicylic acid is added to effectively mask the Fe³⁺And does not interfere with the results.

When Fe is contained in the sample³⁺The content is more than 0.02 percent, a certain amount of ascorbic acid is added into the conical flask, and a certain amount of aminosalicylic acid is added.

Step six, calculating results

The content of gadolinium oxide in the sample is calculated by the following formula (1) in terms of mass fraction W in percent (%):

in the formula:

w is the mass fraction of gadolinium oxide in the sample, and the unit is percentage (%).

C_EDTA-calibrated EDTA concentration in moles per liter (mol/L).

V_EDTAConsumption of EDTA volume in milliliters (mL)

m-weight (g) of the sample to be weighed.

0.8674 mass fraction of gadolinium in gadolinium oxide.

And the calculation result retains the last two digits of the decimal point.

Example 1:

step one, preparation and weighing of samples

Grinding and sieving the gadolinium-containing uranium dioxide pellets to obtain pellets with the particle size of less than 154 mu m, and storing the pellets in a dry and clean polyethylene bottle, wherein the sample weight is 1.0 g;

step two, sample dissolution

Weighing 1.0g of sample, accurately obtaining the sample to 0.0001g, adding 5mL of hydrochloric acid solution, placing the sample on an electric hot plate (200 ℃) to be heated and dissolved, dropwise adding hydrogen peroxide until the sample is a bright yellow solution, and then taking down the sample when the volume is 1-1.5 mL, and cooling the sample for later use.

Step three, separating uranium

Transferring the dissolved solution into a separating funnel containing 10mL of extracting agent by using 5.5mol/L nitric acid solution, violently shaking, standing, transferring into a 300mL conical flask after the solution is completely layered, and adding water to 20mL after the extraction process is repeated once.

Step four, acidity control and solution titration

Adding 1 drop of methyl orange indicator into a conical flask, adjusting the solution to turn yellow by using ammonia water and hydrochloric acid, adding 5mL of hexamethylenetetramine buffer solution, adding 2 drops of xylenol orange indicator, titrating by using EDTA (ethylene diamine tetraacetic acid) until the solution turns yellow from red, namely the titration end point, and calculating the result.

Step five, Fe³⁺Interference cancellation

If the sample contains Fe³⁺Adding ascorbic acid to the mixture to obtain Fe³⁺After reduction, aminosalicylic acid is added to mask the Fe, and the aminosalicylic acid is added to effectively mask the Fe³⁺And make a knotThe interference is not generated.

Step six, calculating results

The content of gadolinium oxide in the sample is calculated by the following formula (1) in terms of mass fraction W in percent (%):

in the formula:

w is the mass fraction of gadolinium oxide in the sample, and the unit is percentage (%).

C_EDTA-calibrated EDTA concentration in moles per liter (mol/L).

V_EDTAConsumption of EDTA volume in milliliters (mL)

m-weight (g) of the sample to be weighed.

0.8674 mass fraction of gadolinium in gadolinium oxide.

And the calculation result retains the last two digits of the decimal point.

In the disclosed embodiments of the present invention, only methods related to the disclosed embodiments are referred to, and other methods may refer to general designs, and under the condition of no conflict, the same embodiment and different embodiments of the present invention may be combined with each other;

the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included in the scope of the present invention.