An efficient preparation process for an alumina target sample

Abstract

This application relates to the technical field of target sample preparation, and specifically relates to an efficient preparation process for an alumina target sample. The efficient preparation process for the alumina target sample includes the following steps: Step S1, preparing a reaction solution; Step S2, preparing a modified precursor; Step S3, preparing an alumina target sample. In this application, a functionalized surfactant is added. The functionalized surfactant contains modified chitosan and polyethylene glycol. The modified chitosan contains a chitosan structure, carboxyl groups, and ether bonds. The phenyl groups and hydroxyl groups in the molecule of chitosan can serve as anchoring groups to bind to the surface of the modified precursor through multi-point adsorption. The presence of carboxyl groups can, on the one hand, improve the hydrophilicity of the modified chitosan, and on the other hand, it can reduce the hydrogen bond interaction of the molecular chain. At the same time, carboxyl groups are easily decomposed into carbon dioxide at high temperatures. Both ether bonds and polyethylene glycol can form hydrogen bond interactions with the modified precursor. Through their synergistic effects, the dispersibility of the alumina target sample is improved.

Description

Technical Field

[0001] The present application relates to the technical field of target preparation, and more specifically, it relates to an efficient preparation process for alumina target samples. Background Art

[0002] Dating of loess sediments is an important means to study the geological history, climate change, and human activity history in the Loess Plateau region. Among them, Be (such as 10 Be) and Al (such as 27 Al), as cosmogenic radioactive isotopes, play an important role in the dating of loess sediments. They provide an innovative dual-isotope combined ratio method to determine the age of loess sediments. Due to various advantages such as a wide dating range and little interference from climate factors, the Be / Al dual-isotope combined ratio method has broad application prospects in the field of loess sediment dating.

[0003] However, since the content of argon in the atmosphere is only about 1%, the production amount of 26 Al is about three orders of magnitude lower than that of 10 Be. And aluminum is the third most abundant major element in the earth's crust, resulting in the ratio of 26 Al / 27 Al in loess sediments being at the -15 order of magnitude, only one order of magnitude higher than the detection limit of -16 order of magnitude of a 3MV accelerator mass spectrometer. Therefore, it is necessary to prepare target samples with stable and strong beam current output to ensure high-precision isotope measurement, thereby improving the accuracy of the obtained data.

[0004] The existing production process for preparing alumina target samples is: purification of aluminum hydroxide precipitate → drying → high-temperature roasting → copper doping → grinding → obtaining the finished target sample. However, the alumina particles prepared by the existing technology are relatively hard and not easy to grind. Small particles will pop out during the grinding process, resulting in sample loss and the potential for cross-contamination. At the same time, the dispersibility of the alumina target sample is poor, affecting the data error of sample testing. Therefore, it is necessary to provide an alumina target sample that can meet the requirements of stable testing and has a relatively high 27 27Al beam current output. Summary of the Invention

[0005] The purpose of the present invention is to provide an alumina target sample that can achieve a small sample volume, good dispersibility, stably output a relatively high 27Al beam current, and realize stable testing.

[0006] Technical problems to be solved by the present invention: The alumina particles prepared by the prior art are relatively hard and not easy to grind. During the grinding process, small particles will pop out, resulting in loss of samples and potential cross-contamination. At the same time, the dispersibility of the alumina target sample is poor, affecting the data error of sample testing. By improving the above process, the present invention aims to obtain an alumina target sample that can achieve a small sample amount, good dispersibility, stably output a relatively high 27Al beam current, and enable stable testing.

[0007] To solve the technical problems mentioned in the background art, the present application provides an efficient preparation process for an alumina target sample.

[0008] An efficient preparation process for an alumina target sample includes the following steps:

[0009] Step S1, preparing the reaction solution: Dissolve aluminum nitrate and ammonium bicarbonate in a mixed solution a of equal mass of deionized water and absolute ethanol respectively, and set aside to obtain aluminum nitrate reaction solution 1 and ammonium bicarbonate reaction solution 2 respectively. Among them, the mass ratio of aluminum nitrate, ammonium bicarbonate and the total amount of mixed solution a is 10 - 12:19 - 23:60 - 80. In the mixed solution a, the mass ratio of deionized water to absolute ethanol is 1 - 3:1.

[0010] Step S2, preparing the modified precursor: Add the functionalized surfactant to aluminum nitrate reaction solution 1, stir evenly, heat up to 45 - 55°C, and while stirring, dropwise add ammonium bicarbonate reaction solution 2, controlling to finish dropping within 30 minutes. After dropping, heat up to 145 - 155°C and stir and react for 0.4 - 0.8 h. After the reaction ends, carry out suction filtration, precipitation, washing, and drying to obtain the modified precursor. Among them, the mass ratio of the functionalized surfactant, aluminum nitrate reaction solution 1 and ammonium bicarbonate reaction solution 2 is 1 - 1.2:55 - 65:55 - 65. In the above process, using aluminum nitrate as the aluminum source and ammonium bicarbonate as the precipitating agent, the modified precursor is obtained by the coprecipitation method.

[0011] Step S3, preparing the alumina target sample: In an atmosphere of H2 - N2, heat the modified precursor at a uniform rate to 550 - 650°C, keep the temperature for reaction for 6.5 - 7.5 h, cool to room temperature, add copper powder and absolute ethanol to the calcined product, grind and dry to obtain the alumina target sample. The mass ratio of the modified precursor, copper powder and absolute ethanol is 2.8 - 3:2:0.02 - 0.04.

[0012] Preferably, in step S2, the functionalized surfactant is composed of modified chitosan, polyethylene glycol and deionized water mixed in a mass ratio of 2 - 4:1:22 - 26.

[0013] Preferably, in step S3, the heating rate of the uniform heating is 8 - 10°C / min.

[0014] Preferably, the modified chitosan is prepared by the following steps:

[0015] Step A1: Chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and N-hydroxysuccinimide are added to an acetic acid aqueous solution, stirred evenly, and then an aqueous solution of maleic anhydride is added. The temperature is raised to 54 - 66 °C, and the mixture is stirred and reacted for 1 - 2 h. After cooling to room temperature, the pH value is adjusted to neutral, and then filtered under reduced pressure, washed, and dried to obtain amidated chitosan. Among them, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution, and maleic anhydride aqueous solution is 0.6: 3 - 4: 2.6 - 3.0: 25 - 35: 46 - 52. The maleic anhydride aqueous solution is obtained by ultrasonic dispersion of maleic anhydride and deionized water in a mass ratio of 1:10. The mass fraction of the acetic acid aqueous solution is 0.6 - 1%. In the above process, the active amino group on chitosan and the anhydride group on maleic anhydride undergo a ring-opening esterification reaction to obtain amidated chitosan;

[0016] Step A2: Amidated chitosan and polyethylene glycol are added to dichlorodiethyl ether, and the temperature is raised to 50 - 60 °C and stirred evenly. While stirring, an aqueous solution of sodium hydroxide is added dropwise, and the addition is completed within 10 min. After the addition is completed, the temperature is raised to 164 - 172 °C, and the mixture is continuously stirred and reacted for 2.4 - 2.8 h. A saturated sodium chloride aqueous solution is added and the pH is adjusted to neutral, then filtered, washed, and dried to obtain modified chitosan. Among them, the mass ratio of amidated chitosan, polyethylene glycol, dichlorodiethyl ether, aqueous sodium hydroxide solution, and saturated sodium chloride aqueous solution is 0.6 - 1.2: 0.02 - 0.04: 42 - 54: 20 - 30: 60 - 70. The mass fraction of the aqueous sodium hydroxide solution is 22 - 26%. In the above reaction process, dichlorodiethyl ether is used as a solvent. Under alkaline conditions, amidated chitosan and polyethylene glycol undergo an etherification reaction to obtain modified chitosan.

[0017] In summary, the present application has the following beneficial effects: A functional surfactant is added in the present application. The functional surfactant contains modified chitosan and polyethylene glycol. The modified chitosan contains a chitosan structure, carboxyl groups and ether bonds. The chitosan structure itself not only has natural degradability, but also the phenyl groups and hydroxyl groups in the chitosan molecule can serve as anchoring groups to bind to the surface of the modified precursor through multi-point adsorption. Supported by its macromolecular structure, the modified precursor molecules are not prone to agglomeration and stacking phenomena, improving the dispersion stability of the modified precursor. The presence of carboxyl groups can, on the one hand, improve the hydrophilicity of the modified chitosan and further improve its dispersion performance for the modified precursor. On the other hand, it can reduce the hydrogen bond interaction between molecular chains, making the structure looser. At the same time, carboxyl groups are easily decomposed into carbon dioxide at high temperatures, releasing gas and accelerating the breaking of the carbon skeleton, promoting calcination decomposition. The presence of ether bonds can form hydrogen bonds or produce physical adsorption with the modified precursor, adsorbing on the surface of the modified precursor to form a layer of polymer protective film. At the same time, the long carbon chain molecular bonds extend into the aqueous solution, making the protective film increase a certain thickness, realizing steric hindrance effect and further improving the dispersion of the alumina target sample. The presence of polyethylene glycol can, on the one hand, produce hydrogen bond interaction with the modified precursor, and on the other hand, it produces CO2 and H2O during the subsequent calcination process, creating voids on the surface of the modified chitosan and further improving the dispersion of the alumina target sample. In summary, the target sample prepared in the present application has high dispersion and a high specific surface area. Compared with the traditional preparation method, not only the required sample amount is small, but also it can stably output a relatively high 27 Al beam current. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a schematic diagram of the stability test of the alumina target samples prepared in Example 1 and Comparative Example 1 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following further details the present application with reference to the embodiments.

[0021] The chitosan (CAS number; 9012-76-4 , degree of deacetylation ≥ 75%) used in the embodiments and comparative examples of the present application was purchased from Aladdin Reagent Network; the polyethylene glycol was polyethylene glycol 2000, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0022] Preparation Examples 1-3 and Comparative Preparation Examples 1-2 provide a modified chitosan.

[0023] Preparation Example 1

[0024] This preparation example provides a modified chitosan, which is prepared by the following steps:

[0025] Step A1: Chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added to an acetic acid aqueous solution, stirred at 450 rpm for 15 min until homogeneous, then maleic anhydride aqueous solution is added, the temperature is raised to 54 °C, stirred and reacted for 1 h, cooled to room temperature, the pH value is adjusted to neutral with 0.4 M sodium hydroxide aqueous solution, filtered under reduced pressure, and then washed 3 times with absolute ethanol and deionized water successively, and dried at 55 °C to constant weight to obtain amidated chitosan. Among them, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution and maleic anhydride aqueous solution is 0.6:3:2.6:25:46. The maleic anhydride aqueous solution is obtained by ultrasonic dispersion of maleic anhydride and deionized water according to the mass ratio of 1:10, and the mass fraction of the acetic acid aqueous solution is 0.6%;

[0026] Step A2: Amidated chitosan and polyethylene glycol are added to dichlorodiethyl ether, the temperature is raised to 50 °C, stirred at 550 rpm for 12 min until homogeneous, sodium hydroxide aqueous solution is added dropwise while stirring, and the addition is completed within 10 min. After the addition is completed, the temperature is raised to 164 °C, the rotation speed is kept unchanged, and the stirring reaction is continued for 2.4 h. Saturated sodium chloride aqueous solution is added and the pH is adjusted to neutral with 0.6 M hydrochloric acid aqueous solution, filtered, and then washed 3 times with absolute ethanol and deionized water successively. The filter cake is dried at 50 °C to constant weight to obtain modified chitosan. Among them, the mass ratio of amidated chitosan, polyethylene glycol, dichlorodiethyl ether, sodium hydroxide aqueous solution and saturated sodium chloride aqueous solution is 0.6:0.02:42:20:60, and the mass fraction of the sodium hydroxide aqueous solution is 22%.

[0027] Preparation Example 2

[0028] This preparation example provides a modified chitosan, which is prepared by the following steps:

[0029] Step A1: Chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and N-hydroxysuccinimide were added to an acetic acid aqueous solution. The mixture was stirred at 500 rpm for 20 min until homogeneous. Then, an aqueous maleic anhydride solution was added, and the temperature was raised to 60 °C. The mixture was stirred and reacted for 1.5 h, cooled to room temperature, and the pH value was adjusted to neutral with 0.5 M sodium hydroxide aqueous solution. Then, it was washed 4 times with absolute ethanol and deionized water successively, and dried at 60 °C to constant weight to obtain amidated chitosan. Among them, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution, and maleic anhydride aqueous solution was 0.6:3.5:2.8:30:49. The maleic anhydride aqueous solution was obtained by ultrasonic dispersion of maleic anhydride and deionized water according to a mass ratio of 1:10, and the mass fraction of the acetic acid aqueous solution was 0.8%.

[0030] Step A2: Amidated chitosan and polyethylene glycol were added to dichlorodiethyl ether. The temperature was raised to 55 °C, and the mixture was stirred at 600 rpm for 16 min until homogeneous. While stirring, an aqueous sodium hydroxide solution was added dropwise, and the addition was controlled to be completed within 10 min. After the addition was completed, the temperature was raised to 168 °C, and the rotation speed was maintained unchanged. The mixture was continuously stirred and reacted for 2.6 h. A saturated sodium chloride aqueous solution was added, and the pH was adjusted to neutral with 0.8 M hydrochloric acid aqueous solution. It was filtered by suction, and then washed 4 times with absolute ethanol and deionized water successively. The filter cake was dried at 55 °C to constant weight to obtain modified chitosan. Among them, the mass ratio of amidated chitosan, polyethylene glycol, dichlorodiethyl ether, aqueous sodium hydroxide solution, and saturated sodium chloride aqueous solution was 0.9:0.03:48:25:65, and the mass fraction of the aqueous sodium hydroxide solution was 24%.

[0031] Preparation Example 3

[0032] This preparation example provides a modified chitosan, which is prepared by the following steps:

[0033] Step A1: Chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and N-hydroxysuccinimide were added to an acetic acid aqueous solution and stirred evenly. Then, an aqueous maleic anhydride solution was added, and the temperature was raised to 66 °C. The mixture was stirred and reacted for 2 h, cooled to room temperature, and the pH value was adjusted to neutral with 0.6 M sodium hydroxide aqueous solution. Then, it was washed 5 times with absolute ethanol and deionized water successively, and dried at 65 °C to constant weight to obtain amidated chitosan. Among them, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution, and maleic anhydride aqueous solution was 0.6:4:3.0:35:52. The maleic anhydride aqueous solution was obtained by ultrasonic dispersion of maleic anhydride and deionized water according to a mass ratio of 1:10, and the mass fraction of the acetic acid aqueous solution was 1%.

[0034] Step A2: Add amidated chitosan and polyethylene glycol into dichlorodiethyl ether, heat up to 60 °C, stir for 20 min at a rotation speed of 650 rpm until uniform. While stirring, dropwise add an aqueous sodium hydroxide solution, control to finish dropping within 10 min. After dropping, heat up to 172 °C, maintain the rotation speed unchanged, continue to stir and react for 2.8 h. Add saturated sodium chloride aqueous solution and adjust the pH to neutral with 1.0 M hydrochloric acid aqueous solution. Filter by suction, then wash with absolute ethanol and deionized water 5 times in sequence. Place the filter cake in an oven at 60 °C and dry to constant weight to obtain modified chitosan. Among them, the mass ratio of amidated chitosan, polyethylene glycol, dichlorodiethyl ether, aqueous sodium hydroxide solution and saturated sodium chloride aqueous solution is 1.2:0.04:54:30:70, and the mass fraction of the aqueous sodium hydroxide solution is 26%.

[0035] Comparative Preparation Example 1

[0036] This Comparative Preparation Example provides a modified chitosan, which is prepared by the following steps:

[0037] Step A1: Add chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide into acetic acid aqueous solution, stir at a rotation speed of 450 rpm for 15 min until uniform. Then add isopropyl alcohol solution of alkenyl succinic anhydride, heat up to 54 °C, stir and react for 1 h. Cool to room temperature, adjust the pH value to neutral with 0.4 M aqueous sodium hydroxide solution, filter under reduced pressure, then wash with absolute ethanol and deionized water 3 times in sequence. Dry at 55 °C to constant weight to obtain amidated chitosan. Among them, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution and isopropyl alcohol solution of alkenyl succinic anhydride is 0.6:3:2.6:25:46. The isopropyl alcohol solution of alkenyl succinic anhydride is obtained by ultrasonic dispersion of alkenyl succinic anhydride and absolute isopropyl alcohol according to the mass ratio of 1:10, and the mass fraction of the acetic acid aqueous solution is 0.6%;

[0038] Step A2: Add amidated chitosan and polyethylene glycol into dichlorodiethyl ether, heat up to 50 °C, stir for 12 min at a rotation speed of 550 rpm until uniform. While stirring, dropwise add an aqueous sodium hydroxide solution, control to finish dropping within 10 min. After dropping, heat up to 164 °C, maintain the rotation speed unchanged, continue to stir and react for 2.4 h. Add saturated sodium chloride aqueous solution and adjust the pH to neutral with 0.6 M hydrochloric acid aqueous solution. Filter by suction, then wash with absolute ethanol and deionized water 3 times in sequence. Place the filter cake in an oven at 50 °C and dry to constant weight to obtain modified chitosan. Among them, the mass ratio of amidated chitosan, polyethylene glycol, dichlorodiethyl ether, aqueous sodium hydroxide solution and saturated sodium chloride aqueous solution is 0.6:0.02:42:20:60, and the mass fraction of the aqueous sodium hydroxide solution is 22%.

[0039] Comparative Preparation Example 2

[0040] This comparative preparation example provides a modified chitosan, which is prepared by the following steps:

[0041] Step A1: Add chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, and N-hydroxysuccinimide into an acetic acid aqueous solution, stir at a speed of 450 rpm for 15 min until homogeneous, then add a maleic anhydride aqueous solution, heat up to 54 °C, stir and react for 1 h, cool to room temperature, adjust the pH value to neutral with 0.4 M sodium hydroxide aqueous solution, perform vacuum filtration, and then wash with absolute ethanol and deionized water three times each, dry at 55 °C to constant weight to obtain amidated chitosan. Among them, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution, and maleic anhydride aqueous solution is 0.6:3:2.6:25:46. The maleic anhydride aqueous solution is obtained by ultrasonic dispersion of maleic anhydride and deionized water in a mass ratio of 1:10, and the mass fraction of the acetic acid aqueous solution is 0.6%;

[0042] Step A2: Add amidated chitosan and ethylene glycol into dichlorodiethyl ether, heat up to 50 °C, stir at a speed of 550 rpm for 12 min until homogeneous, dropwise add sodium hydroxide aqueous solution while stirring, control to finish dropping within 10 min, after dropping, heat up to 164 °C, maintain the rotation speed unchanged, continue to stir and react for 2.4 h, add saturated sodium chloride aqueous solution and adjust the pH to neutral with 0.6 M hydrochloric acid aqueous solution, perform filtration, and then wash with absolute ethanol and deionized water three times each. Place the filter cake in an oven at 50 °C and dry to constant weight to obtain modified chitosan. Among them, the mass ratio of amidated chitosan, ethylene glycol, dichlorodiethyl ether, sodium hydroxide aqueous solution, and saturated sodium chloride aqueous solution is 0.6:0.02:42:20:60, and the mass fraction of the sodium hydroxide aqueous solution is 22%.

[0043] Examples 1-3 and Comparative Examples 1-4 provide a preparation method for an efficient preparation process of an alumina target sample.

[0044] Example 1

[0045] This example provides an efficient preparation process for an alumina target sample, including the following steps:

[0046] Step S1: Prepare the reaction solution: Dissolve aluminum nitrate and ammonium bicarbonate in a mixed solution a of equal mass of deionized water and absolute ethanol respectively for standby, and obtain aluminum nitrate reaction solution 1 and ammonium bicarbonate reaction solution 2 respectively for standby. Among them, the mass ratio of aluminum nitrate, ammonium bicarbonate, and the total amount of mixed solution a is 10:19:60. In the mixed solution a, the mass ratio of deionized water to absolute ethanol is 1:1;

[0047] Step S2: Prepare the modified precursor: Add the functionalized surfactant into the aluminum nitrate reaction solution 1, stir for 30 min until homogeneous at a controlled rotation speed of 500 rpm, heat up to 45 °C, keep the rotation speed unchanged, dropwise add the ammonium bicarbonate reaction solution 2 while stirring, control to finish dropping within 30 min. After dropping, heat up to 145 °C, stir and react for 0.4 h. After the reaction ends, carry out suction filtration, precipitate, wash with absolute ethanol 3 times, and freeze-dry at -20 °C for 12 h to obtain the modified precursor. Among them, the mass ratio of the functionalized surfactant, the aluminum nitrate reaction solution 1, and the ammonium bicarbonate reaction solution 2 is 1:55:55, and the functionalized surfactant is composed of modified chitosan, polyethylene glycol, and deionized water mixed according to the mass ratio of 2:1:22;

[0048] Step S3: Prepare the alumina target sample: Put the modified precursor in an H2 - N2 atmosphere, heat up uniformly to 550 °C at a heating rate of 8 °C / min, keep the temperature for reaction for 6.5 h, cool to room temperature. Add copper powder and absolute ethanol to the calcined product, grind and dry to obtain the alumina target sample. The mass ratio of the modified precursor, copper powder, and absolute ethanol is 2.8:2:0.02.

[0049] Example 2

[0050] This example provides an efficient preparation process for an alumina target sample, including the following steps:

[0051] Step S1: Prepare the reaction solutions: Dissolve aluminum nitrate and ammonium bicarbonate in the mixed solution a of equal-mass deionized water and absolute ethanol respectively for standby, and obtain the aluminum nitrate reaction solution 1 and the ammonium bicarbonate reaction solution 2 respectively for standby. Among them, the mass ratio of aluminum nitrate, ammonium bicarbonate, and the total amount of the mixed solution a is 11:21:70. In the mixed solution a, the mass ratio of deionized water to absolute ethanol is 2:1;

[0052] Step S2: Prepare the modified precursor: Add the functionalized surfactant into the aluminum nitrate reaction solution 1, stir for 32 min until homogeneous at a controlled rotation speed of 550 rpm, heat up to 50 °C, keep the rotation speed unchanged, dropwise add the ammonium bicarbonate reaction solution 2 while stirring, control to finish dropping within 30 min. After dropping, heat up to 150 °C, stir and react for 0.6 h. After the reaction ends, carry out suction filtration, precipitate, wash with absolute ethanol 4 times, and freeze-dry at -24 °C for 13 h to obtain the modified precursor. Among them, the mass ratio of the functionalized surfactant, the aluminum nitrate reaction solution 1, and the ammonium bicarbonate reaction solution 2 is 1.1:60:60, and the functionalized surfactant is composed of modified chitosan, polyethylene glycol, and deionized water mixed according to the mass ratio of 3:1:24;

[0053] Step S3: Preparation of alumina target sample: The modified precursor is heated at a heating rate of 9 °C / min in an H2-N2 atmosphere to 600 °C at a constant speed, held for reaction for 7.0 h, cooled to room temperature, the calcined product is added with copper powder and absolute ethanol, ground and dried to obtain the alumina target sample. The mass ratio of the modified precursor, copper powder and absolute ethanol is 2.9:2:0.03.

[0054] Example 3

[0055] This example provides a high-efficiency preparation process for alumina target samples, including the following steps:

[0056] Step S1: Preparation of reaction solution: Dissolve aluminum nitrate and ammonium bicarbonate in a mixed solution a of equal mass of deionized water and absolute ethanol respectively for standby, and obtain aluminum nitrate reaction solution 1 and ammonium bicarbonate reaction solution 2 respectively for standby. Among them, the mass ratio of aluminum nitrate, ammonium bicarbonate and the total amount of mixed solution a is 12:23:80. In the mixed solution a, the mass ratio of deionized water and absolute ethanol is 3:1;

[0057] Step S2: Preparation of modified precursor: Add the functionalized surfactant to aluminum nitrate reaction solution 1, stir at a speed of 600 rpm for 34 min until uniform, heat up to 55 °C, keep the speed unchanged, dropwise add ammonium bicarbonate reaction solution 2 while stirring, and control to finish dropping within 30 min. After dropping, heat up to 155 °C and stir for reaction for 0.8 h. After the reaction, filter by suction, precipitate, wash with absolute ethanol 5 times, and freeze-dry at -28 °C for 14 h to obtain the modified precursor. Among them, the mass ratio of the functionalized surfactant, aluminum nitrate reaction solution 1 and ammonium bicarbonate reaction solution 2 is 1.2:65:65. The functionalized surfactant is composed of modified chitosan, polyethylene glycol and deionized water mixed according to the mass ratio of 4:1:26;

[0058] Step S3: Preparation of alumina target sample: The modified precursor is heated at a heating rate of 10 °C / min in an H2-N2 atmosphere to 650 °C at a constant speed, held for reaction for 7.5 h, cooled to room temperature, the calcined product is added with copper powder and absolute ethanol, ground and dried to obtain the alumina target sample. The mass ratio of the modified precursor, copper powder and absolute ethanol is 3:2:0.04.

[0059] Comparative Example 1

[0060] Comparative Example 1 is the same as Example 1, the only difference is that the functionalized surfactant in Example 1 is replaced by the functionalized surfactant prepared in Comparative Preparation Example 1.

[0061] Comparative Example 2

[0062] Comparative Example 2 is the same as Example 1, the only difference is that the functionalized surfactant in Example 1 is replaced by the functionalized surfactant prepared in Comparative Preparation Example 2.

[0063] Comparative Example 3

[0064] Comparative Example 3 is the same as Example 1, except that the functional surfactant is prepared by mixing modified chitosan and deionized water in a mass ratio of 3:22.

[0065] Comparative Example 4

[0066] Comparative Example 4 is the same as Example 1, except that the functional surfactant is prepared by mixing polyethylene glycol and deionized water in a mass ratio of 3:22.

[0067] Performance Test

[0068] Now, the performance of the alumina target samples prepared in Examples 1-3 and Comparative Examples 1-4 was detected, and the results are shown in Table 1;

[0069] 1. Hardness test: The nano-indentation hardness test was carried out using a nano-indentation instrument, and the specific test results are shown in Table 2 below:

[0070] Table 1 Hardness test of alumina target samples prepared in Examples 1-3 and Comparative Examples 1-4

[0071]

[0072] As can be seen from Table 1, compared with Comparative Examples 1-4, the nano-hardness of the alumina target samples prepared in Examples 1-3 is lower and they are easier to grind.

[0073] 2. Particle size distribution: The measurement was carried out in accordance with the standards of GB / T 1480-2012 "Metal Powders - Determination of Particle Size by Dry Sieving Method" and GB / T 19077-2016 "Particle Size Analysis - Laser Diffraction Method";

[0074] Table 2 Particle size distribution of alumina target samples prepared in Examples 1-3 and Comparative Examples 1-4

[0075]

[0076] As can be seen from the data in Table 2, the alumina target samples prepared by the preparation method provided by the present invention have a narrow particle size distribution and are very suitable for the preparation of alumina target samples for the Be / Al dual-isotope combined ratio method.

[0077] 3. Stability test: Taking the target samples prepared in Example 1 and Comparative Example 1 as examples, the beam current intensity and stability of them were respectively tested using an accelerator mass spectrometer. Among them, the specific test results are as follows Figure 1 shown;

[0078] From Figure 1It can be seen that, compared with Comparative Example 1, after 18 rounds of testing, the alumina target sample prepared in Example 1 is not only more stable, but also has a higher beam current intensity, meeting the test requirements of the Be / Al dual nuclide combined use ratio method.

[0079] This specific embodiment is only an interpretation of the present application and does not limit the present application. Those skilled in the art can make modifications to this embodiment without creative contributions according to needs after reading this specification, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. An efficient preparation process of an alumina target sample, characterized in that: The following steps are involved: Step S1, preparing a reaction solution: dissolving aluminum nitrate and ammonium bicarbonate in a mixed solution a of equal mass of deionized water and anhydrous ethanol, respectively, and setting aside, to obtain a reaction solution 1 and a reaction solution 2, respectively, and setting aside; Step S2, preparing a modified precursor: adding a functionalized surfactant to the reaction solution 1, stirring evenly, heating to 45-55°C, adding the reaction solution 2 dropwise while stirring, and controlling the dripping to be completed within 30 minutes. After the dripping is completed, heating to 145-155°C, stirring and reacting for 0.4-0.8 hours, after the reaction is completed, filtering, precipitating, washing, and drying to obtain a modified precursor, wherein the functionalized surfactant is prepared by mixing modified chitosan, polyethylene glycol, and deionized water in a mass ratio of 2-4:1:22-26; Step S3, preparing an alumina target sample: uniformly heating the modified precursor to 550-650°C in a H2-N2 atmosphere, keeping the temperature for reaction for 6.5-7.5h, cooling to room temperature, adding copper powder and anhydrous ethanol to the calcined product, grinding and drying, and obtaining an alumina target sample; The modified chitosan is prepared by the following steps: Step A1, chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide are added to an acetic acid aqueous solution, stirred evenly, and then an aqueous maleic anhydride solution is added, the temperature is raised to 54-66° C., stirred for reaction for 1-2 hours, cooled to room temperature, the pH value is adjusted to neutral, filtered under reduced pressure, washed, and dried to obtain amidated chitosan; Step A2, adding amidated chitosan and polyethylene glycol to dichlorodiethyl ether, heating to 50-60° C., stirring evenly, adding sodium hydroxide aqueous solution dropwise while stirring, and controlling the dripping to be completed within 10 minutes. After the dripping is completed, heating to 164-172° C., continuing to stir and react for 2.4-2.8 hours, adding saturated sodium chloride aqueous solution and adjusting the pH to neutral, filtering, washing, and drying to obtain modified chitosan.

2. The efficient preparation process of alumina target sample according to claim 1, characterized in that: In the step S1, the mass ratio of aluminum nitrate, ammonium bicarbonate and the total amount of the mixed solution a is 10-12:19-23:60-80, and in the mixed solution a, the mass ratio of deionized water and anhydrous ethanol is 1-3:

1.

3. The efficient preparation process of alumina target sample according to claim 1, characterized in that: In the step S2, the mass ratio of the functionalized surfactant, the reaction solution 1 and the reaction solution 2 is 1-1.2:55-65:55-65.

4. The efficient preparation process of alumina target sample according to claim 1, characterized in that: In the step S3, the mass ratio of the modified precursor, the copper powder and the anhydrous ethanol is 2.8-3:2:0.02-0.

04.

5. The efficient preparation process of alumina target sample according to claim 1, characterized in that: In the step A1, the mass ratio of chitosan, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, acetic acid aqueous solution and maleic anhydride aqueous solution is 0.6:3-4:2.6-3.0:25-35:46-52, the maleic anhydride aqueous solution is obtained by ultrasonic dispersion of maleic anhydride and deionized water in a mass ratio of 1:10, and the mass fraction of the acetic acid aqueous solution is 0.6-1%.

6. The efficient preparation process of alumina target sample according to claim 1, characterized in that: In the step A2, the mass ratio of amidated chitosan, polyethylene glycol, dichlorodiethyl ether, sodium hydroxide aqueous solution and saturated sodium chloride aqueous solution is 0.6-1.2: 0.02-0.04: 42-54: 20-30: 60-70, and the mass fraction of sodium hydroxide aqueous solution is 22-26%.

7. The efficient preparation process of alumina target sample according to claim 1, characterized in that: In step S3, the uniform heating rate is 8-10°C / min.

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