Phosphate functionalized silicon-based solid adsorbent and application thereof

Abstract

The invention discloses a phosphate functionalized silicon-based solid adsorbent and application thereof, and belongs to the technical field of yttrium separation and purification, a preparation method comprises the following steps: step 1, synthesizing silicon-based resin particles SiO2-P by using spherical porous silicon dioxide as a solid-phase carrier and styrene as a raw material through an in-situ polymerization technology, and 2, synthesizing the phosphate-functionalized silicon-based solid adsorbent HDEHP / SiO2-P by using di (2-ethylhexyl) phosphate HDEHP as a raw material and utilizing a vacuum impregnation technology. Therefore, the phosphate functionalized silicon-based solid adsorbent and the application thereof are adopted in the invention. The phosphate can specifically and selectively extract trivalent yttrium ions, so that efficient separation of yttrium and strontium is realized, high-purity yttrium can be obtained through separation and purification after elution, and a solid adsorbent can be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of yttrium separation and purification, and in particular to a phosphate functionalized silicon-based solid adsorbent and application thereof. Background Art

[0002] Cancer has become the leading cause of death for people under 70 worldwide. Among them, primary liver cancer is the sixth most commonly diagnosed cancer and the third leading cause of cancer death in 2022. In recent years, there have been nearly 400,000 new cases of liver cancer in my country each year, and the number of deaths from liver cancer accounts for more than 47% of the world's total. The "Healthy China 2030" Planning Outline proposes that by 2030, the overall five-year cancer survival rate should be increased by 15%. Therefore, the prevention and treatment of liver cancer has become a focus of attention in the field of liver cancer in China.

[0003] Y-90 microsphere therapy is recommended in the "Guidelines for the Diagnosis and Treatment of Primary Liver Cancer". 90Y is a decay daughter of 90Sr and an ideal internal irradiation beta nuclide with a half-life of 64.1h and a maximum beta ray energy of 2.28MeV. It kills and inhibits tumor cells by releasing beta rays to achieve a precise therapeutic effect. At present, all medical 90Y isotopes in my country rely on imports. Therefore, developing a technology to separate and extract medical 90Y isotopes from the existing nuclear industry system is of great significance to the self-supply of yttrium-90 strategic resources.

[0004] Parent strontium-90 is considered to be a bone-conducting agent, and the maximum allowable value of human body load is only 740KBq. Therefore, the purity of 90Y radionuclide should be greater than 99.998%, that is, the 90Sr contamination factor should be less than 2×10-5 (20ppm). In order to eliminate the radiation toxicity risk caused by 90Sr, the efficient separation and purification of strontium and yttrium in the process of producing yttrium-90 using strontium-yttrium generator has important clinical application significance.

[0005] At present, the research methods used to separate yttrium mainly include chemical precipitation, solvent extraction, liquid membrane, electrochemical method, adsorption, and chromatographic column separation. Compared with other methods, which have the disadvantages of low separation purity, poor selectivity, and high temperature requirements, the chromatographic column separation method has the advantages of high separation efficiency, good mobile phase selectivity, high purity of effluent components, low cost, and strong reusability. The existing yttrium adsorption and separation materials mainly include titanium dioxide, organic resins, ionic liquid membranes, nanomagnetic materials, etc. There are few types of materials, and the materials have the disadvantages of poor selectivity, low adsorption capacity, difficult solid-liquid separation, and low separation coefficient. Therefore, it is of great significance to develop a separation and purification material that has good selectivity for yttrium under acidic conditions, high separation coefficient, and can be reused. Summary of the invention

[0006] The purpose of the present application is to provide a phosphate functionalized silicon-based solid adsorbent and its application. The phosphate of the present invention can achieve specific selective extraction of trivalent yttrium ions, thereby realizing efficient separation of yttrium and strontium. After elution, high-purity yttrium can be separated and purified, and the solid adsorbent can be reused.

[0007] Preferably, in step 1, spherical porous silica is used as a solid phase carrier, styrene is used as a raw material, and silicon-based resin particles SiO2-P are synthesized by in-situ polymerization technology. The synthesis route is as follows:

[0008]

[0009] Step 2, using di(2-ethylhexyl) phosphate HDEHP as a raw material, and using vacuum impregnation technology to synthesize phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P;

[0010]

[0011] Preferably, the specific steps of step one are: selecting spherical porous silica particles as a solid phase carrier, loading the spherical porous silica particles into a rotary evaporation bottle, using a vacuum pump to evacuate the bottle to negative pressure, and adjusting the rotation speed of the rotary evaporator; connecting a nitrogen bottle, introducing nitrogen to normal pressure and then evacuating to vacuum; back-sucking a uniform mixture of diluent, monomer, and initiator into the rotary evaporation bottle to uniformly mix the mixture with the silica particles; then placing the rotary evaporation bottle in a silicone oil bath and heating it; post-treating the obtained styrene polymer-silica resin to obtain silicon-based resin particles SiO2-P.

[0012] Preferably, the specific steps of step 2 are: adding silicon-based resin particles SiO2-P and methanol into a glass bottle, placing it in a shaker for shaking; filtering with a sand core funnel after shaking, placing it in a vacuum drying oven for drying; then placing it in a rotary evaporation bottle; adding a mixture of di(2-ethylhexyl) phosphate HDEHP and a diluent into the rotary evaporation bottle, adjusting the rotation speed of the rotary evaporator, rotating and standing, and then placing the rotary evaporation bottle in a water bath for heating, and removing excess diluent under reduced pressure; placing the white powder particles obtained by evaporation into a vacuum drying oven for low-temperature drying, and finally obtaining a phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P.

[0013] Preferably, the mass ratio of monomer: diluent: initiator is 90-120:320-390:0.3-2.5; the monomer is divinylbenzene and styrene in a mass ratio of 1:3; the diluent is acetophenone and diethyl phthalate in a mass ratio of 3:2; the initiator is azobisisobutyronitrile; and the mass ratio of spherical porous silica to monomer is 10-50:7-36.

[0014] Preferably, the particle size of the spherical porous silica particles is 75-150 μm; the vacuuming time is 30-40 minutes; the specific steps of heating in the silicone oil bath are heating to 333K, maintaining for 1h-1.5h, then heating at 343K for 2h-2.5h, then heating at 353K for 2h-2.5h, and finally maintaining at 363K for 10h-15h.

[0015] Preferably, the post-treatment step is to wash the obtained styrene polymer-silica resin with acetone and ultrapure water respectively to remove residual polymer; after washing, transfer to a vacuum drying oven for low-temperature drying to finally obtain silicon-based resin particles SiO2-P.

[0016] Preferably, the mass ratio of HDEHP:SiO2-P is 1:2; and the heating in the water bath is specifically: slowly heating to 308K and maintaining for 1h-1.5h.

[0017] The present application provides an application of a phosphate functionalized silicon-based solid adsorbent in separating and purifying yttrium from an acidic solution.

[0018] Preferably, the separation and purification method is to fill the chromatographic column with an adsorbent, pre-balance the filled column with the medium to be separated, perform adsorption separation on the solution containing strontium and yttrium, collect the effluent in equal volumes until the yttrium ion concentration in the effluent is close to the yttrium concentration in the feed solution; elute the filled column after yttrium adsorption; and desorb yttrium from the elute filled column with a high acid solution of the corresponding medium until the yttrium concentration in the effluent is lower than 0 mg / L.

[0019] Preferably, the medium to be separated is one or more of hydrochloric acid, nitric acid, and acetic acid; the concentration of yttrium in the yttrium-containing acidic solution is 1-100 mg / L, and the concentration of strontium is 100-20000 mg / L.

[0020] Therefore, the present application provides a phosphate functionalized silicon-based solid adsorbent and its application, which has the following beneficial effects:

[0021] (1) The adsorbent has a developed ordered mesoporous structure, good adsorption selectivity, excellent separation characteristics, high mechanical strength and chemical stability, stronger acid corrosion resistance, and higher product purity. No chemical reagents need to be added during the reaction, and it is pollution-free and does not produce any waste, so it has broad market prospects.

[0022] (2) The adsorbent of the present invention can separate and purify yttrium from a variety of acid systems, is simple and efficient to operate, has simple process equipment, low production cost, and is suitable for producing high-purity yttrium. No organic solvent is used in the separation process, and the separation solution can be recycled. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1It is a synthetic flow chart of the phosphate functionalized silicon-based solid adsorbent (HDEHP / SiO2-P) of the present invention;

[0024] Figure 2 It is a scanning electron microscope image of the phosphate functionalized silicon-based solid adsorbent (HDEHP / SiO2-P) of the present invention.

[0025] Figure 3 is the pore size distribution diagram of the phosphate functionalized silicon-based solid adsorbent (HDEHP / SiO2-P) of the present invention;

[0026] Figure 4 is a thermogravimetric diagram of the phosphate functionalized silicon-based solid adsorbent (HDEHP / SiO2-P) in an embodiment of the present invention;

[0027] Figure 5 is the adsorption efficiency of the solid adsorbent (HDEHP / SiO2-P) in Example 4;

[0028] Figure 6 is the partition coefficient of the solid adsorbent (HDEHP / SiO2-P) in Example 4;

[0029] Figure 7 These are (a) the breakthrough curve and (b) the purification curve of yttrium in the column separation of strontium and yttrium by the solid adsorbent (HDEHP / SiO2-P) in hydrochloric acid medium in Example 4. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further illustrated by the following examples.

[0031] Example 1

[0032] Preparation of HDEHP / SiO2-P: 7.2g of spherical porous silica particles were placed in a rotary evaporation flask, and a vacuum pump was used to draw negative pressure, and then a nitrogen bottle was connected to introduce nitrogen, and the vacuum was drawn for 30 minutes. Then a mixture of 10g of monomer (DVB and styrene in a mass ratio of 1:3), 32g of diluent (acetophenone and diethyl phthalate in a mass ratio of 3:2) and 0.3g of initiator (azobisisobutyronitrile) was inhaled into the flask. The rotation speed of the rotary evaporator was adjusted to fully mix the mixture with the silica particles. Then it was slowly heated to 333K in a silicone oil bath, kept for 1 hour, heated at 343K for 2 hours, heated at 353K for 2.5 hours, and finally kept at 363K for 10 hours. The obtained silica grafted styrene polymer resin was washed with acetone and water respectively to remove the polymer on the surface, dried under vacuum, and finally the silicon-based resin particles SiO2-P were obtained;

[0033] Add silicon-based resin particles SiO2-P and methanol into a glass bottle, put it into a shaker for shaking; after shaking, filter it with a sand core funnel and put it into a vacuum drying oven for drying; then put it into a rotary evaporation bottle; add a mixture of di(2-ethylhexyl) phosphate HDEHP (the mass ratio of HDEHP to SiO2-P is 1:2) and a diluent into the rotary evaporation bottle, adjust the rotation speed of the rotary evaporator, rotate and stand, then put the rotary evaporation bottle into a water bath and heat it, slowly heat it to 308K, keep it for 1.5h, and remove the excess diluent under reduced pressure; the white powder particles obtained by evaporation are placed in a vacuum drying oven for low-temperature drying, and finally the phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P is obtained, and the effective content of organic matter is 24.88wt%.

[0034] Example 2

[0035] Preparation of HDEHP / SiO2-P: 24g of spherical porous silica particles were placed in a rotary evaporation flask, and a vacuum pump was used to draw negative pressure, and then a nitrogen bottle was connected to introduce nitrogen, and the vacuum was drawn for 30 minutes. Then a mixture of 33g of monomer (DVB and styrene in a mass ratio of 1:3), 119g of diluent (acetophenone and diethyl phthalate in a mass ratio of 3:2) and 0.5g of initiator (azobisisobutyronitrile) was inhaled into the flask. The rotation speed of the rotary evaporator was adjusted to fully mix the mixture with the silica particles. Then it was slowly heated to 333K in a silicone oil bath, kept for 1 hour, heated at 343K for 2 hours, heated at 353K for 2.5 hours, and finally kept at 363K for 12 hours. The obtained silica-grafted styrene polymer resin was washed with acetone and water respectively to remove the polymer on the surface, dried under vacuum, and finally the silicon-based resin particles SiO2-P were obtained;

[0036] Add silicon-based resin particles SiO2-P and methanol into a glass bottle, put it into a shaker for shaking; after shaking, filter it with a sand core funnel and put it into a vacuum drying oven for drying; then put it into a rotary evaporation bottle; add a mixture of di(2-ethylhexyl) phosphate HDEHP (the mass ratio of HDEHP to SiO2-P is 1:2) and a diluent into the rotary evaporation bottle, adjust the rotation speed of the rotary evaporator, rotate and stand, then put the rotary evaporation bottle into a water bath and heat it, slowly heat it to 308K, keep it for 1.5h, and remove the excess diluent under reduced pressure; the white powder particles obtained by evaporation are placed in a vacuum drying oven for low-temperature drying, and finally a phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P is obtained, and the effective content of organic matter is 26.68wt%, such as Figure 4 shown.

[0037] Example 3

[0038] Preparation of HDEHP / SiO2-P: 36g of spherical porous silica particles were placed in a rotary evaporation flask, and a vacuum pump was used to draw negative pressure, and then a nitrogen bottle was connected to introduce nitrogen, and the vacuum was drawn for 30 minutes. Then a mixture of 50g of monomer (DVB and styrene in a mass ratio of 1:3), 195g of diluent (acetophenone and diethyl phthalate in a mass ratio of 3:2) and 2.5g of initiator (azobisisobutyronitrile) was inhaled into the flask. The rotation speed of the rotary evaporator was adjusted to fully mix the mixture with the silica particles. Then it was slowly heated to 333K in a silicone oil bath, kept for 1.5 hours, heated at 343K for 2.5 hours, heated at 353K for 2.5 hours, and finally kept at 363K for 15 hours. The obtained silica-grafted styrene polymer resin was washed with acetone and water respectively to remove the polymer on the surface, dried under vacuum, and finally the silicon-based resin particles SiO2-P were obtained;

[0039] Add silicon-based resin particles SiO2-P and methanol into a glass bottle, put it into a shaker for shaking; after shaking, filter it with a sand core funnel and put it into a vacuum drying oven for drying; then put it into a rotary evaporation bottle; add a mixture of di(2-ethylhexyl) phosphate HDEHP (the mass ratio of HDEHP to SiO2-P is 1:2) and a diluent into the rotary evaporation bottle, adjust the rotation speed of the rotary evaporator, rotate and stand, then put the rotary evaporation bottle into a water bath and heat it, slowly heat it to 308K, keep it for 1.5h, and remove the excess diluent under reduced pressure; the white powder particles obtained by evaporation are placed in a vacuum drying oven for low-temperature drying, and finally the phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P is obtained, and the effective content of organic matter is 26.95wt%.

[0040] Example 4

[0041] Adsorption experiment of selective adsorption distribution ratio of solid adsorbent HDEHP / SiO2-P

[0042] The adsorbent prepared in Example 1 was used for the adsorption and separation of strontium and yttrium in hydrochloric acid, nitric acid, and acetic acid systems. The acid concentration was 0.1 M, the yttrium concentration was 1 mmol / L, the strontium concentration was 1-2000 mmol / L, the solid-liquid ratio was 5:1 (g / mL), the adsorption time was 24 hours, and the temperature was 25°C. The adsorbent showed good adsorption performance for yttrium in the three solutions. The results are as follows: Figure 5 and Figure 6 shown.

[0043] The steps for column separation and purification of strontium and yttrium in hydrochloric acid medium are as follows:

[0044] The adsorbent prepared in step 1 was filled in an exchange column (Φ3×200mm, column bed volume of 1.4mL), and the 0.1mol / L hydrochloric acid feed solution containing strontium yttrium (yttrium concentration of 1mmol / L, strontium concentration of 2000mmol / L) was adsorbed and separated using the above-mentioned filled column. Before adsorption and separation, the filled column was pre-balanced with 20mL of 0.1mol / L hydrochloric acid solution free of metal ions. Then, the strontium yttrium-containing solution was adsorbed, and the outflow of about 5mL / tube was collected. The strontium yttrium concentration in the collected liquid was analyzed and tested using an inductively coupled plasma spectrometer until the strontium yttrium concentration in the outflow liquid was equal to that of the feed liquid; the results are as follows: Figure 7 As shown in (a), the solid adsorbent HDEHP / SiO2-P exhibits excellent selectivity. In a mixed solution of strontium and yttrium with a high molar ratio, it only exhibits an adsorption effect on yttrium. The separation of yttrium was tested. After the adsorption, 100 mL of 0.1 mol / L hydrochloric acid solution was used for elution; finally, 6 mol / L hydrochloric acid was used to desorb and purify the adsorbed yttrium. The results are shown in Figure 1. Figure 7 As shown in (b), the elution rate is 100%, the purity of yttrium in the solution after elution is 100%, and strontium impurities are almost undetectable.

[0045] The steps for column separation and purification of strontium and yttrium in acetic acid medium are as follows:

[0046] The adsorbent prepared in step 1 is filled in an exchange column (Φ3×200mm, column bed volume is 1.4mL), and the 0.1mol / L acetic acid feed solution containing strontium yttrium (yttrium concentration is 1mmol / L, strontium concentration is 2000mmol / L) is adsorbed and separated by the above-mentioned filling column. Before adsorption and separation, the filling column is pre-balanced with 20mL 0.1mol / L acetic acid solution without metal ions. Then the solution containing strontium yttrium is adsorbed, and the outflow of about 5mL / tube is collected, and the strontium yttrium concentration in the collected liquid is analyzed and tested by inductively coupled plasma spectrometer until the strontium yttrium concentration in the outflow liquid is equal to the feed liquid; after the adsorption is completed, it is rinsed with 100mL0.1mol / L acetic acid solution; finally, the adsorbed yttrium is desorbed and purified with 6mol / L acetic acid.

[0047] The steps for column separation and purification of strontium and yttrium in nitric acid medium are as follows:

[0048] The adsorbent prepared in step 1 is filled in an exchange column (Φ3×200mm, column bed volume is 1.4mL), and the 0.1mol / L nitric acid feed solution containing strontium yttrium (yttrium concentration is 1mmol / L, strontium concentration is 2000mmol / L) is adsorbed and separated by the above-mentioned filling column. Before adsorption and separation, the filling column is pre-balanced with 20mL 0.1mol / L nitric acid solution without metal ions. Then the solution containing strontium yttrium is adsorbed, and the outflow of about 5mL / tube is collected, and the strontium yttrium concentration in the collected liquid is analyzed and tested by an inductively coupled plasma spectrometer until the strontium yttrium concentration in the outflow liquid is equal to the feed liquid; after the adsorption is completed, it is rinsed with 100mL0.1mol / L nitric acid solution; finally, the adsorbed yttrium is desorbed and purified with 6mol / L nitric acid. Therefore, the present application provides a phosphate functionalized silicon-based solid adsorbent and its application. The phosphate of the present invention can achieve specific selective extraction of trivalent yttrium ions, thereby realizing efficient separation of yttrium and strontium. After elution, high-purity yttrium can be separated and purified, and the solid adsorbent can be reused.

[0049] In the description of this specification, the description with reference to the terms "an experimental example", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the experimental example or example are included in at least one experimental example or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same experimental example or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more experimental examples or examples in a suitable manner.

[0050] Finally, it should be noted that the above experimental examples are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred experimental examples, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A phosphate functionalized silicon-based solid adsorbent, characterized in that: The preparation method comprises the following steps: Step 1: Using spherical porous silica as a solid phase carrier and styrene as a raw material, the silicon-based resin particles SiO2-P are synthesized by in-situ polymerization technology. The synthesis route is as follows: Step 2, using di(2-ethylhexyl) phosphate HDEHP as a raw material, and using vacuum impregnation technology to synthesize phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P; 2. The phosphate functionalized silicon-based solid adsorbent according to claim 1, characterized in that: The specific steps of step one are: select spherical porous silica particles as the solid phase carrier, load the spherical porous silica particles into a rotary evaporation bottle, use a vacuum pump to evacuate the bottle to negative pressure, and adjust the rotation speed of the rotary evaporator; connect a nitrogen bottle, pass nitrogen to normal pressure and then evacuate to vacuum; suck the uniform mixture of diluent, monomer, and initiator into the rotary evaporation bottle to evenly mix the mixture with the silica particles; then put the rotary evaporation bottle into a silicone oil bath and heat it; post-treat the obtained styrene polymer-silica resin to obtain silicon-based resin particles SiO2-P.

3. The method for preparing a phosphate functionalized silicon-based solid adsorbent according to claim 1, characterized in that: The specific steps of step 2 are: adding silicon-based resin particles SiO2-P and methanol into a glass bottle, placing it in a shaker for shaking; filtering with a sand core funnel after shaking, placing it in a vacuum drying oven for drying; then placing it in a rotary evaporation bottle; adding a mixture of di(2-ethylhexyl) phosphate HDEHP and a diluent into the rotary evaporation bottle, adjusting the rotation speed of the rotary evaporator, rotating and standing, and then placing the rotary evaporation bottle in a water bath for heating, and removing excess diluent under reduced pressure; the white powder particles obtained by evaporation are placed in a vacuum drying oven for low-temperature drying, and finally the phosphate functionalized silicon-based solid adsorbent HDEHP / SiO2-P is obtained.

4. The phosphate functionalized silicon-based solid adsorbent according to claim 2, characterized in that: The mass ratio of monomer: diluent: initiator is 90-120:320-390:0.3-2.5; the monomer is divinylbenzene and styrene in a mass ratio of 1:3; the diluent is acetophenone and diethyl phthalate in a mass ratio of 3:2; the initiator is azobisisobutyronitrile; the mass ratio of spherical porous silica to the monomer is 10-50:7-36.

5. The phosphate functionalized silicon-based solid adsorbent according to claim 2, characterized in that: The particle size of the spherical porous silica particles is 75-150 μm; the vacuuming time is 30-40 minutes; the specific steps of heating in the silicone oil bath are heating to 333 K, maintaining for 1 h-1.5 h, then heating at 343 K for 2 h-2.5 h, then heating at 353 K for 2 h-2.5 h, and finally maintaining at 363 K for 10 h-15 h.

6. The phosphate functionalized silicon-based solid adsorbent according to claim 2, characterized in that: The post-treatment step is to wash the obtained styrene polymer-silica resin with acetone and ultrapure water respectively to remove residual polymer; after washing, transfer it to a vacuum drying oven for low-temperature drying to finally obtain silicon-based resin particles SiO2-P.

7. The phosphate functionalized silicon-based solid adsorbent according to claim 3, characterized in that: The mass ratio of HDEHP:SiO2-P is 1:2; the heating in the water bath is as follows: slowly heating to 308K and maintaining for 1h-1.5h.

8. Use of the phosphate functionalized silicon-based solid adsorbent according to any one of claims 1 to 7 as an adsorbent for separating and purifying yttrium from an acidic solution.

9. Use of the phosphate functionalized silicon-based solid adsorbent according to any one of claim 8 as an adsorbent for separating and purifying yttrium from an acidic solution, characterized in that: The separation and purification method comprises the following steps: filling an adsorbent in a chromatographic column, pre-balancing the filling column with a medium to be separated, performing adsorption separation on a solution containing strontium and yttrium, collecting an equal volume of effluent until the yttrium ion concentration in the effluent is close to the yttrium concentration in the feed solution; eluting the filling column after yttrium adsorption; and desorbing yttrium from the eluted filling column with a high acid solution of a corresponding medium until the yttrium concentration in the effluent is lower than 0 mg / L.

10. Use of the phosphate functionalized silicon-based solid adsorbent according to any one of claim 8 as an adsorbent for separating and purifying yttrium from an acidic solution, characterized in that: The medium to be separated is one or more of hydrochloric acid, nitric acid and acetic acid; the concentration of yttrium in the yttrium-containing acidic solution is 1-100 mg / L, and the concentration of strontium is 100-20000 mg / L.

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