CN103344982A - Radiochemical analyzing method of Sr-90 in soil - Google Patents

Abstract

The invention relates to a radiochemical analyzing method of Sr-90 in soil. The radiochemical analyzing method of the Sr-90 in soil comprises the following steps that 1, pretreatment of soil samples is conducted; 2, sediment and concentration of strontium and yttrium are conducted by oxalic acid; 3, oxalate sediments are dissolved by nitric acid; 4, Sr-90 is separated by resin columns: strontium resin is soaked by distilled water and packed into columns in a wet-process mode, clear liquid obtained in step 3 flows through the resin columns, elution is conducted, desorption is conducted, and desorption solution is collected; 5, chemical yield measurement: sediment of strontium in the desorption solution is conducted by oxalic acid, and the strontium is washed and dried to achieve constant weight; 6, liquid flash measurement is conducted: the sediment is dissolved by nitric acid, liquid flash liquid is added to measure the belta factor; 7, radioactive activity of 90Sr-90Y in soil is calculated. The radiochemical analyzing method of the Sr-90 in soil can rapidly analyze the 90Sr content in soil samples in a radiochemical mode, the chemical yield of the 90Sr is about 60 percent during the whole process, analyzing time is less than 12 hours, the minimum detectable activity is 2 Bq/kg, and when the minimum detectable activity is compared with the industrial standard (EJ/T1035-1996) in the express method, and the minimum detectable activity and the industrial standard are consistent within the 5% error range.

Description

The radiochemical analysis method of Sr-90 in a kind of soil

Technical field

The invention belongs to nucleic detection technique field in the soil, be specifically related to the radiochemical analysis method of Sr-90 in a kind of soil.

Background technology

Sr-90(namely ⁹⁰Sr) being important fission product, belonging to pure beta emitter, have yield height, long characteristics of life-span, is highly toxic bone seeking nuclide. ⁹⁰Sr is the radioactive nuclide of paying close attention to the most in the environmental monitoring, but can be subjected to the interference of other impurity nucleic when radioactivity survey, usually need to put divide from.In samples such as water, plant ass and urine ⁹⁰The radiochemical analysis method of Sr is existing more report both at home and abroad.Because pedotheque system complexity, wherein constituent contents such as calcium, magnesium, iron are more much higher than strontium, also have uranium, radium, thorium, potassium and decay daughter nucleic thereof ⁹⁰Y and various artificial radionuclide are given ⁹⁰The radiochemical analysis of Sr brings big difficulty.

China is in the pedotheque at present ⁹⁰The analysis of Sr extensively adopts the nuclear industry standard " in the soil ⁹⁰The mensuration of Sr ", comprising express method and two kinds of routine analyzers of placement methods.The key step of express method is that concentrate strontium and yttrium, sulfide precipitation of hydrochloric acid leaching soil, oxalate precipitation measured except bismuth, the stratography of HDEHP extration resin, yttrium oxalate precipitation source processed, low background beta measurement mechanism ⁹⁰Y, be 2-3 days full-range analysis time.Placement methods is that the outflow liquid after stratography in the express method is regulated the pH value, again by the chromatograph post, will flow out liquid and place after 14 days, makes ⁹⁰Sr- ⁹⁰Y reaches the decay balance, with chromatographic column repeated isolation and measurement ⁹⁰Y, be 15-20 days full-range analysis time.No matter this shows, be express method or placement methods, all has the shortcoming that operation steps is many, the flow process time is long, is not suitable in a large amount of ambient soil samples ⁹⁰The requirement that Sr analyzes; In addition, also supposition in the said method ⁹⁰Sr and daughter thereof ⁹⁰Y has reached balance, by daughter ⁹⁰Y measures indirectly ⁹⁰Sr is not suitable for the quick measurement of recent contaminated samples.

Summary of the invention

At the defective that exists in the prior art, the purpose of this invention is to provide the radiochemical analysis method of Sr-90 in the soil that a kind of convenience is quick and measuring error is little.

For reaching above purpose, the technical solution used in the present invention is: the radiochemical analysis method of Sr-90 in a kind of soil may further comprise the steps:

(1) pedotheque pre-service: fetch earth the earth sample in porcelain crucible, add Sr ²⁺Carrier solution, calcination, cooling; With the pedotheque after the acid dissolving calcination, cooling separates then, and the washing residue merges supernatant and cleansing solution, abandons residue;

(2) concentrate strontium and yttrium of oxalic acid precipitation: add excessive solid oxalic acid in the solution after the merging that obtains to step (1), heating for dissolving is regulated the pH value to 5-6, boils, and cooling separates, the oxalate precipitation of washing gained, centrifuging;

(3) nitric acid dissolve oxalate precipitation: analyze the oxalate precipitation that pure nitric acid obtains step (2) with 15M and dissolve evaporate to dryness solution, repeated several times fully; Make the medium dissolves oxalate precipitation with 3-M nitric acid again, get clear liquid;

(4) resin column separates ⁹⁰Sr: two-(the tert-butylcyclohexyl)-18-that will do is preced with 6 crown ether extration resins (trade name Sr.spec) and puts into the distilled water immersion more than 12 hours, wet method dress post, and with the nitric acid pre-equilibration resin column of using as medium in the step (3), make the clear liquid of step (3) flow through resin column then, use the nitric acid drip washing of using as medium in the step (3) again, use the distilled water desorb at last, collect stripping liquid, record drip washing simultaneously and namely separate t1 constantly the zero hour;

(5) measure chemical yield: with the stripping liquid that distilled water diluting step (4) obtains, add excessive solid oxalic acid, heating for dissolving is regulated the pH value to 9-10, boils, and cooling separates, washs resulting strontium oxalate precipitation, is dried to constant weight, according to adding Sr ²⁺The amount of Sr is calculated Sr in the strontium oxalate precipitation that the amount of carrier and recovery obtain ²⁺The chemical yield of carrier;

(6) liquid dodge to be measured: add the nitric acid of using as medium in the step (3) in the strontium oxalate precipitation after the constant weight, make the dissolving fully of strontium oxalate precipitation, get strontium nitrate solution; Strontium nitrate solution is transferred to liquid dodges measuring tube, in liquid sudden strain of a muscle measuring tube, add scintillation solution, shake up, carry out liquid and dodge measurement, record the beta activity counting, and the record measurement t2 zero hour;

(7) according to Sr ²⁺The chemical yield of carrier and beta activity counting calculate in the pedotheque ⁹⁰The radioactivity of Sr.

Further, in the step (1), add Sr in the pedotheque ²⁺When carrying out calcination behind the carrier solution, calcination is 1 hour under 600 ℃ of temperature.

Further again, in the step (1), with the pedotheque after the method dissolving calcination of hydrochloric acid digestion, with the hydrochloric acid of 6mol/L, digestion is 1 hour under the condensing reflux condition during digestion.

Further, in the step (3), the nitric acid of using as medium is 3M nitric acid.

Further, in the step (4), two-(the tert-butylcyclohexyl)-18-that does is preced with the Sr that adds in the weight of 6 crown ether extration resins and the step (1) ²⁺The weight relationships of carrier is 5-10mgSr ²⁺/ g dried resin.

Further again, use two-(tert-butylcyclohexyl)-18-to be preced with 6 crown ether extration resins in the step (4) and separate ⁹⁰During Sr, the clear liquid that makes step (3) flows through resin column with the flow velocity of 1-2mL/min.

Further, when the washing strontium oxalate precipitates in the step (5), successively with 1wt% oxalic acid, each 15mL washing of absolute ethyl alcohol; Resulting strontium oxalate is deposited under 110 ℃ and is dried to constant weight.

Further, in the step (6), to add scintillation solution be Ultima Gold LLT.

The present invention adopt to strontium have special efficacy optionally the Sr.spec resin column be the main separation and purification means, dodge in conjunction with soil pre-service, oxalate precipitation and liquid and measure etc., set up in a kind of quick radiochemical analysis pedotheque ⁹⁰The method of Sr content, whole process is right ⁹⁰The chemical yield of Sr is about 60%, and analysis time, the minimum detectable activity of method was 2Bq/kg less than 12h, and with the express method comparison in the nuclear industry rower, both are consistent in 5% error range.

Description of drawings

Fig. 1 is the schematic flow sheet of the radiochemical analysis method of Sr-90 in a kind of soil provided by the invention.

Embodiment

Below in conjunction with the drawings and specific embodiments the present invention is further described.

As shown in Figure 1, the radiochemical analysis method of Sr-90 in a kind of soil provided by the present invention may further comprise the steps:

(1) pedotheque pre-service: fetch earth the earth sample in porcelain crucible, add a certain amount of Sr ²⁺Carrier solution, calcination, cooling; With the hydrochloric acid digestion or with the pedotheque after the nitration mixture dissolving calcination, cool off then, separate, the washing residue merges supernatant and cleansing solution, abandons residue;

(2) concentrate strontium and yttrium of oxalic acid precipitation: add excessive solid oxalic acid in the solution after the merging that obtains to step (1), heating for dissolving is regulated the pH value to 5-6, boils, and cooling separates, the oxalate precipitation of washing gained, centrifuging;

(3) nitric acid dissolve oxalate precipitation: analyze the oxalate precipitation that pure nitric acid (concentration is about 15M) obtains step (2) with 15M and dissolve evaporate to dryness solution, repeated several times fully; Make the medium dissolves oxalate precipitation with 3-8M nitric acid again, get clear liquid;

(4) resin column separates ⁹⁰Sr: take by weighing dried Sr.spec, the Sr that adds in the weight of dried Sr.spec and the step (1) ²⁺The weight relationships of carrier is 5-10mgSr ²⁺/ g, dried resin is put into distilled water to be soaked more than 12 hours, wet method dress post, with the nitric acid pre-equilibration resin column of using as medium in the step (3), the clear liquid that makes step (3) flows through resin column with the flow velocity of 1-2mL/min, with the nitric acid drip washing of using as medium in the step (3), uses the distilled water desorb, collect stripping liquid, record desorb simultaneously and begin to the middle t1 constantly that finishes;

(5) chemical yield is measured: with the stripping liquid that distilled water diluting step (4) obtains, add excessive solid oxalic acid, heating for dissolving is regulated the pH value to 9-10, boils, and cooling separates, washs resulting strontium oxalate precipitation, is dried to constant weight; According to adding Sr ²⁺The amount of Sr is calculated Sr in the strontium oxalate precipitation that the amount of carrier and recovery obtain ²⁺The chemical yield of carrier;

(6) liquid dodge to be measured: add the nitric acid of using as medium in the step (3) in the strontium oxalate precipitation after the constant weight, make the dissolving fully of strontium oxalate precipitation, get strontium nitrate solution; Strontium nitrate solution is transferred to liquid dodges measuring tube, in liquid sudden strain of a muscle measuring tube, add scintillation solution, shake up, carry out liquid and dodge measurement, record the beta activity counting, and the record measurement t2 zero hour;

(7) according to Sr ²⁺The chemical yield of carrier and beta activity counting calculate in the soil ⁹⁰Sr- ⁹⁰The radioactivity of Y, concrete computing method are as follows:

According to mother and sons' body radioactivity decay and growth relationship, t1 extremely measures moment t2 in the time from separating constantly, the total beta activity counting N that measures _TIn comprised ⁹⁰Sr and the daughter that grows out ⁹⁰Y, 1., 2. their activity satisfy following formula:

A _T=A _Sr+A _Y=N _T/(60*ε) ①

$A_Y=A_{\mathrm{Sr}}\×e^{{\mathrm{\λ}}_{\mathrm{Sr}}\mathrm{\Δt}}\×\frac{{\mathrm{\λ}}_{\mathrm{Sr}}{\mathrm{\λ}}_Y}{{\mathrm{\λ}}_Y-{\mathrm{\λ}}_{\mathrm{Sr}}}\×(e^{-{\mathrm{\λ}}_{\mathrm{Sr}}\mathrm{\Δt}}-e^{-{\mathrm{\λ}}_Y\mathrm{\Δt}})$ ②

Wherein:

A _T: ⁹⁰Sr and grow ⁹⁰Y total activity/Bq;

A _Sr, A _Y: be respectively ⁹⁰Sr, ⁹⁰Activity/Bq of Y;

N _T: measurement ⁹⁰Sr and grow ⁹⁰Y gross-count rate/cpm;

ε: ⁹⁰Sr, ⁹⁰The detection efficiency that Y is total is approximately equal to 100%;

λ _Sr, λ _Y: be respectively ⁹⁰Sr, ⁹⁰Disintegration constant/s of Y ^-1

△ t: separate the moment to the time interval of measuring the zero hour, i.e. (t2-t1)/s

Earlier liquid is dodged the total beta activity counting N that records _T1. the substitution formula obtains A _TThen with the A that obtains _TValue and formula 2. equation the right while substitution formula 1. in, can obtain ⁹⁰The radioactivity of Sr. ⁹⁰The twice of Sr activity is in the soil ⁹⁰Sr- ⁹⁰The gross activity activity of Y balanced body.

In said method step (1), pedotheque adds Sr ²⁺When carrying out calcination behind the carrier solution, temperature is 600 ℃ of calcinations 1 hour in muffle furnace.During pedotheque after the method for the following adopted hydrochloric acid digestion dissolving calcination, the hydrochloric acid that can use 6mol/L during digestion digestion 1 hour under the condensing reflux condition.

In said method step (2), can regulate the pH value to 5-6 with strong aqua (25wt%).

In said method step (3), the nitric acid of using as medium preferably adopts 3M nitric acid.In this step, during the nitric acid dissolve oxalate precipitation used as medium, if the solution muddiness, suction filtration is got clear liquid.

In said method step (5), during washing strontium oxalate precipitation, can be successively with 1% oxalic acid, each 15mL washing of absolute ethyl alcohol; Then the strontium oxalate that obtains is deposited under 110 ℃ and is dried to constant weight.

In said method step (6), can adopt 20mL liquid to dodge measuring tube, add the 16mL scintillation solution, add scintillation solution and can be Ultima Gold LLT.

Herein, measurement unit " M " expression mol/L.Wt% represents percentage by weight.

Below describe the present invention in detail with specific embodiment, the reagent among the embodiment, material, instrument all can be buied from market.

Embodiment 1-3

Specific analytical method is as follows:

1) pedotheque pre-service:

Get 10g contaminated soil sample in the 100mL porcelain crucible, adding 0.1g concentration is that the strontium carrier solution of 100mg/g (namely contains 10mg Sr ²⁺Carrier), parallel three parts, sample number into spectrum is 1#, 2#, 3#, corresponding embodiment 1,2,3, and at 600 ℃ of following calcination 1h of muffle furnace, cooling.

Pedotheque after the calcination is transferred in the 1000mL cucurbit that has water condensing tube, added 140mL6mol/L hydrochloric acid, 1h is boiled in heating, cooling, centrifugal, supernatant is collected in the 500mL beaker, uses 40mL1mol/L salt acid elution residue more once, supernatant and cleansing solution are merged, abandon residue.

2) concentrate strontium and yttrium of oxalic acid precipitation:

Add 10g oxalic acid in the solution after merging to step 1), heating for dissolving is with strong aqua (25%, about 44mL) regulates the pH value to 5-6, boiled 5 minutes, cooling 10min, the centrifuging sediment, and with centrifuging again after the 70mL hot distilled water washing, obtain the oxalate precipitation of strontium, yttrium.

3) nitric acid dissolve oxalate precipitation:

With 20ml, 15M nitric acid dissolve step 2) oxalate precipitation of resulting strontium, yttrium, be evaporated near doing.Repeat 3 times.

Whether use 30mL3mol/L nitric acid dissolve oxalate precipitation again, it is transparent to observe solution, if the solution muddiness is got clear liquid with G5 sintered glass funnel suction filtration.

4) resin column separates ⁹⁰Sr:

Take by weighing 3g and do Sr.spec, distillation bubble 12 hours, wet method dress post (column diameter: 10mm, the post height of bed: 100mm), and with 100mL3mol/L nitric acid pre-equilibration pillar.

With the flow velocity upper prop of the resulting clear liquid of step 3) with 1.2mL/min, use the drip washing of 100mL3mol/L nitric acid then, use the desorb of 30mL distilled water again, collect stripping liquid to the 200mL beaker, record desorb simultaneously and begin to the middle t1 constantly that finishes.

5) chemical yield is measured:

Replenish 20mL distilled water in the beaker that holds stripping liquid, add 200mg oxalic acid, heating for dissolving, regulate the pH value to 9-10 with strong aqua, boil 10min, cooling, with the G4 sintered-glass filter crucible suction filtration of constant weight, sediment separate out is used 1wt% oxalic acid, each 15mL washing precipitation of absolute ethyl alcohol more successively, and dry strontium oxalate is precipitated to constant weight under 110 ℃.

According to adding Sr ²⁺The amount of Sr is calculated Sr in the strontium oxalate precipitation that the amount of carrier and recovery obtain ²⁺The chemical yield of carrier the results are shown in table 1.

6) liquid dodges and measures:

After the strontium oxalate precipitation constant weight, add the 3mol/L nitric acid of 1mL low-grade fever in the G4 sintered-glass filter crucible, make the dissolving of strontium oxalate precipitation, obtain strontium nitrate solution, be transferred to 20mL liquid and dodge measuring tube, the 3mol/L nitric acid with 1mL heat washs the G4 crucible at twice again, cleansing solution is incorporated in liquid dodges in the measuring tube.

Dodge adding 16mL Ultima Gold LLT scintillation solution in the measuring tube to liquid, shake up, carry out liquid and dodge measurement, obtain beta activity counting situation, the record measurement begins to the middle t2 constantly that finishes.

7) calculate in the soil ⁹⁰Sr- ⁹⁰The radioactivity of Y the results are shown in table 1.

Embodiment 4-5

Get close to two parts in little contaminated soil sample of background, sample number into spectrum is 4# and 5#, corresponding embodiment 4 and 5, and the consumption of doing Sr.spec is 3g, other concrete operations steps are with embodiment 1-3.Analysis result is listed in table 1.

Table 1

Above-described embodiment the has adopted methods analyst provided by the invention different pedotheque of pollution level has obtained in the sample ⁹⁰The content of Sr, and with the nuclear industry rower in express method comparison, both are consistent in 5% error range.Whole process is about 60% to the chemical yield of Sr, and analysis time is less than 12h.

Above-described embodiment just illustrates of the present invention, and the present invention also can implement with other ad hoc fashion or other particular form, and does not depart from main idea of the present invention or essential characteristic.Therefore, the embodiment of description all should be considered as illustrative from any aspect but not be determinate.Scope of the present invention should be by additional claim explanation, and the intention of any and claim and the variation of scope equivalence also should be within the scope of the present invention.

Claims (8)

1. the radiochemical analysis method of Sr-90 in the soil may further comprise the steps:

(1) pedotheque pre-service: fetch earth the earth sample in porcelain crucible, add Sr ²⁺Carrier solution, calcination, cooling; With the pedotheque after the acid dissolving calcination, cooling separates then, and the washing residue merges supernatant and cleansing solution, abandons residue;

(2) concentrate strontium and yttrium of oxalic acid precipitation: add excessive solid oxalic acid in the solution after the merging that obtains to step (1), heating for dissolving is regulated the pH value to 5-6, boils, and cooling separates, the oxalate precipitation of washing gained, centrifuging;

(3) nitric acid dissolve oxalate precipitation: analyze the oxalate precipitation that pure nitric acid obtains step (2) with 15M and dissolve evaporate to dryness solution, repeated several times fully; Make the medium dissolves oxalate precipitation with 3-8M nitric acid again, get clear liquid;

(4) resin column separates ⁹⁰Sr: two-(the tert-butylcyclohexyl)-18-that will do is preced with 6 crown ether extration resins and puts into the distilled water immersion more than 12 hours, wet method dress post, and with the nitric acid pre-equilibration resin column of using as medium in the step (3), make the clear liquid of step (3) flow through resin column then, use the nitric acid drip washing of using as medium in the step (3) again, use the distilled water desorb at last, collect stripping liquid, record drip washing simultaneously and namely separate t1 constantly the zero hour;

(5) measure chemical yield: with the stripping liquid that distilled water diluting step (4) obtains, add excessive solid oxalic acid, heating for dissolving is regulated the pH value to 9-10, boils, and cooling separates, washs resulting strontium oxalate precipitation, is dried to constant weight, according to adding Sr ²⁺The amount of Sr is calculated Sr in the strontium oxalate precipitation that the amount of carrier and recovery obtain ²⁺The chemical yield of carrier;

(6) liquid dodge to be measured: add the nitric acid of using as medium in the step (3) in the strontium oxalate precipitation after the constant weight, make the dissolving fully of strontium oxalate precipitation, get strontium nitrate solution; Strontium nitrate solution is transferred to liquid dodges measuring tube, in liquid sudden strain of a muscle measuring tube, add scintillation solution, shake up, carry out liquid and dodge measurement, record the beta activity counting, and the record measurement t2 zero hour;

(7) according to Sr ²⁺The chemical yield of carrier and beta activity counting calculate in the pedotheque ⁹⁰The radioactivity of Sr.

2. the radiochemical analysis method of Sr-90 in a kind of soil according to claim 1 is characterized in that, in the step (1), adds Sr in the pedotheque ²⁺When carrying out calcination behind the carrier solution, calcination is 1 hour under 600 ℃ of temperature.

3. the radiochemical analysis method of Sr-90 in a kind of soil according to claim 2 is characterized in that, in the step (1), with the pedotheque after the method dissolving calcination of hydrochloric acid digestion, with the hydrochloric acid of 6mol/L, digestion is 1 hour under the condensing reflux condition during digestion.

4. the radiochemical analysis method of Sr-90 in a kind of soil according to claim 1 is characterized in that, in the step (3), the nitric acid of using as medium is 3M nitric acid.

5. according to the radiochemical analysis method of Sr-90 in the arbitrary described a kind of soil of claim 1-4, it is characterized in that in the step (4), two-(the tert-butylcyclohexyl)-18-that does is preced with the Sr that adds in the weight of 6 crown ether extration resins and the step (1) ²⁺The weight relationships of carrier is 5-10mgSr ²⁺/ g dried resin.

6. the radiochemical analysis method of Sr-90 in a kind of soil according to claim 5 is characterized in that, uses two-(tert-butylcyclohexyl)-18-to be preced with 6 crown ether extration resins in the step (4) and separates ⁹⁰During Sr, the clear liquid that makes step (3) flows through resin column with the flow velocity of 1-2mL/min.

7. the radiochemical analysis method of Sr-90 in a kind of soil according to claim 1 is characterized in that, when the washing strontium oxalate precipitates in the step (5), successively with 1wt% oxalic acid, each 15mL washing of absolute ethyl alcohol; Resulting strontium oxalate is deposited under 110 ℃ and is dried to constant weight.

8. according to the radiochemical analysis method of Sr-90 in claim 1 or the 7 described a kind of soil, it is characterized in that, in the step (6), to add scintillation solution be Ultima Gold LLT.

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