Rapid separation method for measuring lithium isotope in brine

Abstract

The invention belongs to the technical field of isotope mass spectrometry analysis and testing, and relates to a rapid separation method for measuring lithium isotopes in brine. The invention aims to solve the problem of influence of cation impurity element sodium and the like in brine on lithium isotope detection, and provides an efficient separation method for measuring lithium isotopes in a high-salt matrix sample. The separation method has the advantages of simple operation steps, good separation effect on other cation interference elements such as sodium, high separation efficiency and the like; comprising the following steps: preparing reagents and materials; filtering the sample; and separating, purifying and enriching lithium. According to the method, the lithium element in the brine is separated and purified by adopting cationic resin and a methanol-dilute nitric acid system; for a brine sample with the lithium content of 200 ng / mL or above, after single cation exchange resin separation, the sodium content in the sample can be reduced to 1 / 2 or below of the lithium content, the influence of other cations in the sample on lithium isotope determination can be eliminated, and the requirements for separation and purification of the lithium element in the brine in the lithium isotope test are met.

Description

Technical Field

[0001] The invention belongs to the technical field of isotope mass spectrometry analysis and testing, and in particular relates to a pre-treatment method for separation and purification of lithium isotopes in brine using a cationic resin. Background Art

[0002] Lithium is an important mineral resource with broad application prospects in new energy, new materials and other fields. Lithium isotope analysis in brine can guide the exploration of mineral resources; by analyzing brine samples from different regions, areas with potential lithium mineralization characteristics can be identified, providing important clues for mineral resource exploration; by analyzing lithium isotopes in brine, geological processes such as groundwater flow, surface water evaporation, mineral dissolution and precipitation can also be understood, as well as how these processes affect the distribution and abundance of lithium isotopes. At the same time, lithium isotope analysis in brine can also evaluate the reserves and quality of lithium resources, providing a scientific basis for the development and utilization of mineral resources.

[0003] Two stable isotopes of lithium 6 Li and 7 Li has a large relative mass difference and a significant mass fractionation effect. Compared with thermal ionization mass spectrometer (TIMS), multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) has the advantages of low injection volume, small memory effect, and rapid determination for its component determination. In the MC-ICP-MS detection process, if the sample contains other impurity elements, it will have a strong interference effect on the determination of lithium isotopes; therefore, it is necessary to separate, purify and enrich the lithium and other impurity elements in the sample before determining the lithium isotope ratio.

[0004] Cationic resins are usually used for lithium separation, and different elution and separation systems have very different separation effects on lithium. According to the distribution coefficient between cations and sulfonated polystyrene resins, sodium is the first metal cation to be eluted from the separation column after lithium elution during the elution process; therefore, the separation and purification effect of lithium can be evaluated by detecting the content of lithium and sodium in the eluent. For brine samples, the main problem is that the content of sodium and other cations in brine is thousands of times higher than that of lithium. For lithium separation in brine, a high-salt matrix, there are cumbersome processes such as low separation efficiency and the need for multiple separations. The commonly used separation process is complicated and time-consuming. Therefore, inventing a method with good separation effect and fast separation speed is conducive to improving the detection efficiency of lithium isotopes in brine. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a highly efficient separation method for lithium elements in brine. Compared with the hydrochloric acid elution process, the separation method adopts an elution system of a methanol solution of nitric acid and a long separation column, and its separation effect can be improved by 5 to 10 times. It can realize a single, rapid and efficient separation of lithium in brine, and improve the detection efficiency of samples.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] S1. Filter the brine sample through a filter membrane;

[0008] S2, pre-equilibration of cation separation column;

[0009] S3, injecting the filtered brine sample into a cation separation column for separation;

[0010] S4. After elution, the lithium-containing eluate is collected to achieve separation.

[0011] In step S1, a 0.45 μm filter membrane is used to filter the sample to remove suspended matter and other insoluble impurities.

[0012] The cation separation column in step S2 is made of quartz, and the inner diameter of the resin-filled part of the separation column is 6-8 mm and the length is about 15-20 cm.

[0013] The cation exchange resin in the cation separation column described in step S2 is generally a strong acid cation exchange resin, such as one or a combination of two or more of AG50W-X12 resin, AG50W-X8 resin, AG MP 50 resin, etc., with a particle size of 200-400 mesh.

[0014] In step S2, the cation exchange resin is pre-equilibrated with a dilute nitric acid alcohol solution;

[0015] The dilute nitric acid alcohol solution is a mixture of 60-63% nitric acid and 40-50wt% methanol solution in a volume ratio of 1:100-150. In some preferred cases, the mixture is formed in a volume ratio of 1:135-140.

[0016] The eluent used in the elution process in step S4 is an alcohol solution of nitric acid.

[0017] The alcohol solution of nitric acid is a mixture of 60-63% nitric acid and 80-90wt% methanol solution in a volume ratio of 1:10-20. In some preferred embodiments, the volume ratio is 1:10-15, and more preferably 1:13.

[0018] The alcohol solution is selected from C1-C4 alcohol solutions.

[0019] In some embodiments, 3-4 mL of nitric acid alcohol solution is added each time for elution, the first 20 mL of the eluate is discarded, and a polytetrafluoroethylene tank is used to receive 20 to 44 mL of the eluate.

[0020] The method for quickly separating lithium from brine and the method for quickly measuring lithium are as follows: the eluent obtained by separation is evaporated to dryness, a nitric acid solution is added thereto and evaporated again, and the test solution obtained by dissolving the eluent with the nitric acid solution is tested.

[0021] The eluent is heated and evaporated to dryness using an electric heating plate, and the heating and evaporation temperature is 80-90°C.

[0022] ICP-MS and ICP-OES were used to determine the contents of lithium, sodium and other elements in the brine samples after separation.

[0023] The present invention uses a methanol solution system of nitric acid to separate and purify lithium on a cationic resin, uses a 15 cm long exchange column, has high separation efficiency, and a stable and reliable elution process. For a brine sample with a lithium content of 200 ng / mL, after a single separation, the sodium content in the sample can be reduced to 1 / 2 or less of the lithium content, and the influence of other cations in the sample on the lithium isotope determination can be eliminated. The Li recovery rate reaches more than 99.8%, which fully meets the requirements for lithium separation and purification in brine in lithium isotope testing. The separation method can also be used for lithium isotope analysis research of other water samples such as lake water, surface runoff water, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a elution curve diagram for separation and purification of lithium element in brine in Example 1 of the present invention.

[0025] Figure 2 The elution curve of AG50W-X12 resin for separating lithium from brine in Comparative Example 2. DETAILED DESCRIPTION

[0026] Typical embodiments that embody the features and advantages of the present invention will be described in detail in the following description. The embodiments described are part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The embodiments described below are exemplary and are intended to explain the rapid separation method for measuring lithium isotopes in brine of the present invention, and should not be understood as limiting the present invention.

[0027] The raw materials used in the examples can be purchased from the market or prepared by conventional methods.

[0028] Example 1

[0029] A method for rapidly separating lithium from brine comprises the following steps:

[0030] S1. Preparation of reagents and materials. Preparation of reagents and cleaning of laboratory utensils are crucial to reducing the experimental background. All materials needed for the experiment must avoid cross contamination between samples. This experiment completed all the operation steps in the clean room. The reagents and solutions used in the laboratory were purified to ensure that the lithium background was low enough. The utensils and materials used were soaked or cleaned with acid to ensure that they would not affect the isotope detection of lithium in the sample. Wet the AG50W-X8 resin with a particle size of 200-400 mesh with high-purity water, soak it in 6mol / L hydrochloric acid solution for 4h, and stir it continuously with a glass rod, then wash it with high-purity water until it is neutral, and use the wet method to load the cation exchange resin into a quartz separation column with an inner diameter of 6mm and a height of 15cm. The amount of resin is about 4.5mL; use nitric acid that has been purified by sub-boiling, prepare a 2% nitric acid solution, prepare a dilute nitric acid alcohol solution as a pre-equilibrium solution, and prepare a nitric acid alcohol solution as an eluent.

[0031] The preparation process of the dilute nitric acid alcohol solution is as follows: a mixture of 63% nitric acid by mass and 50 wt% methanol solution in a volume ratio of 1:139, namely the pre-equilibrium solution.

[0032] The preparation process of the alcohol solution of nitric acid is as follows: the alcohol solution of nitric acid is a mixture of 63% by mass nitric acid and 90wt% by volume methanol solution in a ratio of 1:13, namely, eluent 1.

[0033] A method for rapidly separating lithium from brine comprises the following steps:

[0034] S2. Filter the brine sample through a 0.45 μm filter membrane to remove suspended matter and other insoluble impurities. The lithium content in the sample is required to be 200 ng / mL or above (samples with lithium concentration less than 200 ng / mL need to be concentrated first to increase the lithium concentration);

[0035] S3, use a pipette to transfer 5 mL of pre-equilibration solution to the separation column, repeat 4 times to perform column equilibration before separation;

[0036] S4, use a pipette to transfer 1 mL of the filtered brine sample into the separation column;

[0037] S5. Use a pipette to transfer 4 mL of 1.0 mol / L eluent 1 to the separation column for elution. Repeat 5 times and use a waste liquid cup to receive the 20 mL of eluent. Then, replace it with a polytetrafluoroethylene tank to receive the eluent. Use a pipette to transfer 4 mL of eluent 1 to the separation column. Repeat 6 times and receive the 20-44 mL of eluent. This 24 mL is the lithium component eluent.

[0038] S6, placing the lithium component liquid collected in step S5 on a hot plate, setting the temperature of the hot plate to 80° C., evaporating to dryness, adding 2 mL of 2% nitric acid to dissolve, and evaporating to dryness again, repeating twice;

[0039] S7, adding 2 mL of 2% nitric acid to the sample evaporated in step S6 to dissolve it to obtain a test solution;

[0040] S8. Use a pipette to transfer 100 μL of the test solution, dilute it to 4 mL with 2% nitric acid, determine the concentration of other metal impurities such as lithium and sodium, calculate the eluted lithium content, and divide it by the original lithium content in the sample to obtain the lithium separation recovery rate.

[0041] Adding 20 mL of pre-equilibrium solution in step S3 can improve the equilibrium efficiency of the separation column, facilitate the metal elements in the sample to enter the resin, and facilitate the separation and enrichment of lithium elements in the brine sample. This step allows the ions in the sample to fully bind to the cation exchange resin, and allows the lithium elements in the brine to be collected from the 20 mL of eluent 1, and can be completely collected at the 44 mL (see Figure 1 ), the entire lithium isotope separation process takes about 3 hours. This method greatly improves the separation efficiency of lithium elements in brine samples.

[0042] ICP-MS and ICP-OES were used to determine the contents of lithium and sodium in the brine samples before and after separation, and the ratio of sodium content to lithium content in the samples and the recovery rate of lithium were calculated. The results are shown in the following table:

[0043] Table 1 The sodium / lithium content ratio and lithium recovery results of brine samples before and after separation under eluent 1 system

[0044]

[0045] Note: The lithium content of the water samples in the table ranges from 240ng / mL to 4733ng / mL, and the sodium content ranges from 50μg / mL to 6750μg / mL.

[0046] The results in Table 1 show that the sodium content in the sample dropped to 1 / 2 or less of the lithium content after a single separation by using the eluent 1 system on the cationic resin to separate and purify lithium in brine, which can eliminate the influence of cations in the sample on the lithium isotope determination. The lithium recovery rate reached more than 99.8%, which fully met the requirements of lithium isotope testing for the separation and purification of lithium in brine.

[0047] Example 2

[0048] In this embodiment, AG50W-X8 is used to separate lithium from brine, and a mixture of 63% nitric acid and 90wt% methanol solution in a volume ratio of 1:8.3 is prepared, i.e., eluent 2, and eluent 2 is used as the elution system for separating lithium from brine. It mainly includes the following steps:

[0049] S1. Preparation of reagents and materials. Preparation of reagents and cleaning of laboratory utensils are crucial to reducing the experimental background. All materials needed for the experiment must avoid cross contamination between samples. This experiment completed all the operation steps in the clean room. The reagents and solutions used in the laboratory were purified to ensure that the lithium background was low enough. The utensils and materials used were soaked or cleaned with acid to ensure that they would not affect the isotope detection of lithium in the sample. Wet the AG50W-X8 resin with a particle size of 200-400 mesh with high-purity water, soak it in 6mol / L hydrochloric acid solution for 4h, and stir it continuously with a glass rod, then wash it with high-purity water until it is neutral, and use the wet method to load the cation exchange resin into a quartz separation column with an inner diameter of 6mm and a height of 15cm. The amount of resin is about 4.5mL; use nitric acid that has been purified by sub-boiling, prepare a 2% nitric acid solution, prepare a dilute nitric acid alcohol solution as a pre-equilibrium solution, and prepare a nitric acid alcohol solution as an eluent.

[0050] The preparation process of the dilute nitric acid alcohol solution is as follows: a mixture of nitric acid with a mass fraction of 60-63% and a methanol solution with a volume ratio of 40-50wt% is formed at 1:139, namely, the pre-equilibrium solution.

[0051] The preparation process of the alcohol solution of nitric acid is as follows: the alcohol solution of nitric acid is a mixture of nitric acid with a mass fraction of 60-63% and methanol solution with a volume ratio of 80-90wt% at 1:8.3, namely, the eluent 2.

[0052] S2. Filter the brine sample through a 0.45 μm filter membrane to remove suspended matter and other insoluble impurities. The lithium content in the sample is required to be 200 ng / mL or above (samples with lithium concentration less than 200 ng / mL need to be concentrated first to increase the lithium concentration);

[0053] S3, use a pipette to transfer 5 mL of pre-equilibration solution to the separation column, repeat 4 times to perform column equilibration before separation;

[0054] S4, use a pipette to transfer 1 mL of the filtered brine sample into the separation column;

[0055] S5. Use a pipette to transfer 4 mL of eluent 2 to the separation column for elution. Repeat 5 times and use a waste liquid cup to receive the 20 mL of eluent. Then, replace it with a polytetrafluoroethylene tank to receive the eluent. Use a pipette to transfer 4 mL of eluent 2 to the separation column. Repeat 6 times to receive the 20-44 mL of eluent. This 24 mL is the lithium component eluent.

[0056] S6, placing the lithium component liquid collected in step S5 on a hot plate, setting the temperature of the hot plate to 80° C., evaporating to dryness, adding 2 mL of 2% nitric acid to dissolve, and evaporating to dryness again, repeating twice;

[0057] S7, adding 2 mL of 2% nitric acid to the sample evaporated in step S6 to dissolve it to obtain a test solution;

[0058] S8. Use a pipette to transfer 100 μL of the test solution, dilute it to 4 mL with 2% nitric acid, determine the concentration of other metal impurities such as lithium and sodium, calculate the eluted lithium content, and divide it by the original lithium content in the sample to obtain the lithium separation recovery rate.

[0059] Table 2 The sodium / lithium content ratio and lithium recovery results of brine samples before and after separation under the eluent 2 system

[0060]

[0061] Note: The lithium content of the water samples in the table ranges from 240ng / mL to 4733ng / mL, and the sodium content ranges from 50μg / mL to 6750μg / mL.

[0062] It can be seen from Table 2 above that when the eluent 2 system is used, the separation effect of lithium in the original brine sample is also relatively ideal.

[0063] Example 3

[0064] In this embodiment, AG MP-50 is used to separate lithium from brine, and a mixture of 63% nitric acid and 90wt% methanol solution in a volume ratio of 1:15 is prepared, i.e., eluent 3, and eluent 3 is used as the elution system for separating lithium from brine. It mainly includes the following steps:

[0065] S1. Preparation of reagents and materials. Preparation of reagents and cleaning of laboratory utensils are crucial to reducing the experimental background. All materials needed for the experiment must avoid cross contamination between samples. All operation steps of this experiment were completed in a clean room. The reagents and solutions used in the laboratory were purified to ensure that the background of lithium was low enough. The utensils and materials used were soaked or cleaned with acid to ensure that they would not affect the isotope detection of lithium in the sample. Wet the AGMP-50 resin with a particle size of 200-400 mesh with high-purity water, soak it in 6mol / L hydrochloric acid solution for 4h, and stir it continuously with a glass rod, then wash it with high-purity water until it is neutral, and use a wet method to load the cation exchange resin into a quartz separation column with an inner diameter of 6mm and a height of 15cm. The amount of resin is about 4.5mL; use nitric acid that has been purified by sub-boiling, prepare a 2% nitric acid solution, prepare a dilute nitric acid alcohol solution as a pre-equilibrium solution, and prepare a nitric acid alcohol solution as an eluent.

[0066] The preparation process of the dilute nitric acid alcohol solution is as follows: a mixture of 63% nitric acid by mass and 50 wt% methanol solution in a volume ratio of 1:139, namely the pre-equilibrium solution.

[0067] The preparation process of the alcohol solution of nitric acid is as follows: the alcohol solution of nitric acid is a mixture of 63% by mass nitric acid and 90wt% by volume methanol solution in a ratio of 1:15, namely, the eluent 3.

[0068] S2. Filter the brine sample through a 0.45 μm filter membrane to remove suspended matter and other insoluble impurities. The lithium content in the sample is required to be 200 ng / mL or above (samples with lithium concentration less than 200 ng / mL need to be concentrated first to increase the lithium concentration);

[0069] S3, use a pipette to transfer 5 mL of pre-equilibration solution to the separation column, repeat 4 times to perform column equilibration before separation;

[0070] S4, use a pipette to transfer 1 mL of the filtered brine sample into the separation column;

[0071] S5. Use a pipette to transfer 4 mL of eluent 3 to the separation column for elution. Repeat 5 times and use a waste liquid cup to receive the 20 mL of eluent. Then, replace the cup with a polytetrafluoroethylene tank to receive the eluent. Use a pipette to transfer 4 mL of eluent 3 to the separation column. Repeat 6 times to receive the 20-44 mL of eluent. This 24 mL portion is the lithium component eluent.

[0072] S6, placing the lithium component liquid collected in step S5 on a hot plate, setting the temperature of the hot plate to 80° C., evaporating to dryness, adding 2 mL of 2% nitric acid to dissolve, and evaporating to dryness again, repeating twice;

[0073] S7, adding 2 mL of 2% nitric acid to the sample evaporated in step S6 to dissolve it to obtain a test solution;

[0074] S8. Use a pipette to transfer 100 μL of the test solution, dilute it to 4 mL with 2% nitric acid, determine the concentration of other metal impurities such as lithium and sodium, calculate the eluted lithium content, and divide it by the original lithium content in the sample to obtain the lithium separation recovery rate.

[0075] Table 3 Sodium / lithium content ratio and lithium recovery results of brine samples before and after separation under eluent 3 system

[0076]

[0077] Note: The lithium content of the water samples in the table ranges from 240ng / mL to 4733ng / mL, and the sodium content ranges from 50μg / mL to 6750μg / mL.

[0078] It can be seen from Table 2 above that when the eluent 3 system is used, the separation effect of lithium in the original brine sample is also relatively ideal.

[0079] Comparative Example 1

[0080] The process of separating lithium elements by using cationic resin can also be usually eluted by using a dilute hydrochloric acid system. When using a dilute hydrochloric acid system to separate lithium, it mainly includes the following steps:

[0081] S1. Preparation of reagents and materials. Reagent preparation and cleaning of laboratory utensils are crucial to reducing the experimental background. All materials required for the experiment must avoid cross-contamination between samples. All operating steps in this experiment were completed in a clean room. The reagents and solutions used in the laboratory were purified to ensure that the lithium background was low enough. The utensils and materials used were soaked or cleaned with acid to ensure that they would not affect the isotope detection of lithium in the sample. Wet the AG50W-X8 resin with a particle size of 200-400 mesh with high-purity water, soak it in 6mol / L hydrochloric acid solution for 4h, and stir it continuously with a glass rod, then wash it with high-purity water until it is neutral. Use a wet method to load the cation exchange resin into a quartz separation column with an inner diameter of 6mm and a height of 15cm. The resin dosage is about 4.5mL, filling two resin columns; use sub-boiling distilled hydrochloric acid to prepare a 0.2mol / L hydrochloric acid solution.

[0082] S2. Filter the brine sample through a 0.45 μm filter membrane to remove suspended matter and other insoluble impurities. The lithium content in the sample is required to be 200 ng / mL or above (samples with lithium concentration less than 200 ng / mL need to be concentrated first to increase the lithium concentration);

[0083] S3. From this step, use a waste liquid cup under the separation column; in the first separation column, use a pipette to transfer 5 mL of 0.2 mol / L hydrochloric acid solution to the separation column, repeat 4 times, and balance before column separation;

[0084] S4, use a pipette to transfer 1 mL of the filtered brine sample into the separation column;

[0085] S5. Use a pipette to transfer 5 mL of 0.2 mol / L hydrochloric acid solution into the separation column for elution;

[0086] S6. Use a pipette to transfer 5 mL of secondary deionized water into the separation column, and repeat 6 times to elute the anions.

[0087] S7, use a pipette to transfer 5 mL of 0.2 mol / L hydrochloric acid solution for elution;

[0088] S8. Replace the polytetrafluoroethylene sample cup under the separation column and use a pipette to transfer 5 mL of 0.2 mol / L hydrochloric acid solution. Repeat 27 times to receive the lithium component.

[0089] S9, evaporate the lithium component solution received in step S8, and add 2 mL of 0.2 mol / L hydrochloric acid solution to dissolve it.

[0090] S10, using a pipette, pipette 5 mL of 0.2 mol / L hydrochloric acid solution into the second separation column and add it to the separation column, repeat 4 times to balance the column before separation;

[0091] S11, adding the lithium component redissolution solution obtained in step S9 to the second separation column;

[0092] S12, adding 3 mL of 0.2 mol / L hydrochloric acid solution to the second separation column for elution;

[0093] S13, starting from this step, replace the polytetrafluoroethylene sample cup below the second separation column, add 5mL 0.2mol / L hydrochloric acid solution, repeat 17 times to elute the lithium component;

[0094] S14, placing the lithium component eluate collected in step S13 on a hot plate, setting the temperature of the hot plate to 80° C., evaporating to dryness, adding 2 mL of 2% nitric acid to dissolve, and evaporating to dryness, repeating twice;

[0095] S15. Take 100 μL of the test solution with a pipette, dilute it to 4 mL with 2% nitric acid, determine the concentration of other metal impurities such as lithium and sodium, calculate the eluted lithium content, and divide it by the original lithium content in the sample to obtain the lithium separation recovery rate.

[0096] ICP-MS and ICP-OES were used to determine the contents of lithium and sodium in the brine samples before and after separation, and the ratio of sodium content to lithium content in the samples and the recovery rate of lithium were calculated. The results are shown in Table 3 below:

[0097] Table 3 Sodium / lithium content ratio and lithium recovery results of brine samples before and after separation in dilute hydrochloric acid system

[0098]

[0099]

[0100] Note: The lithium content of the water samples in the table ranges from 240ng / mL to 4733ng / mL, and the sodium content ranges from 50μg / mL to 6750μg / mL.

[0101] It can be found from Table 3 above that when 0.2mol / L hydrochloric acid solution is used to separate lithium from brine, for samples with a sodium / lithium content ratio of about 1000 in the original brine sample, after two column separation processes, the separation effect is not good, and the sodium / lithium content ratio still reaches dozens, which cannot be directly used for the measurement of lithium isotopes, and it is necessary to undergo secondary separation to obtain pure lithium components. This shows that in the process of lithium separation in brine, the separation degree of the dilute hydrochloric acid elution system is small, the entire separation process uses a large amount of dilute hydrochloric acid (about 300mL per sample), takes a long time (more than 16h), and has low separation efficiency and poor separation effect for lithium.

[0102] Comparative Example 2

[0103] At present, the resins used for separating lithium elements in samples using cation exchange resins are mainly sulfonated polystyrene cation exchange resins AG50W-X12, AG50W-X8 and their macroporous forms AG MP-50 and other resins. This comparative example uses AG50W-X12 to separate lithium from brine. Eluent 1 is also used as the elution system for separating lithium from brine. It mainly includes the following steps:

[0104] S1. Preparation of reagents and materials. Reagent preparation and cleaning of laboratory utensils are crucial to reducing the experimental background. All materials required for the experiment must avoid cross-contamination between samples. This experiment completed all operating steps in a clean room. The reagents and solutions used in the laboratory were purified to ensure that the lithium background was low enough. The utensils and materials used were soaked or cleaned with acid to ensure that they would not affect the isotope detection of lithium in the sample. Wet the AG50W-X12 resin with a particle size of 200-400 mesh with high-purity water, soak it in 6mol / L hydrochloric acid solution for 4h, and stir it continuously with a glass rod, then wash it with high-purity water until it is neutral, and use a wet method to load the cation exchange resin into a quartz separation column with an inner diameter of 6mm and a height of 15cm. The amount of resin is about 4.5mL; use nitric acid that has been sub-boiling purified to prepare a 2% nitric acid solution, prepare a pre-equilibrium solution, and prepare eluent 1;

[0105] S2. Filter the brine sample through a 0.45 μm filter membrane to remove suspended matter and other insoluble impurities. The lithium content in the sample is required to be 200 ng / mL or above (samples with lithium concentration less than 200 ng / mL need to be concentrated first to increase the lithium concentration);

[0106] S3, use a pipette to transfer 5 mL of pre-equilibration solution to the separation column, repeat 4 times to perform column equilibration before separation;

[0107] S4, use a pipette to transfer 1 mL of the filtered brine sample into the separation column;

[0108] S5. Use a pipette to transfer 4 mL of eluent 1 each time and add it to the separation column to perform the elution step. Collect the eluent after adding 4 mL of eluent each time separately, dilute it 10 times with 2% nitric acid solution, and then use ICP-MS to determine the lithium content in the eluent added each time. Based on this, draw the elution curve of lithium element in brine separated by AG50W-X12 resin under this elution system. A total of 168 mL of eluent 1 was added this time.

[0109] The elution curve of lithium obtained by the above steps is as follows Figure 2 As shown:

[0110] Depend on Figure 2 It was found that under the same elution conditions, the process of separating lithium using AG50W-X12 resin had a longer elution process, a large volume of eluent (from 40-120 mL), and a long elution process (more than 8 hours). Compared with AG50W-X8 resin, its separation efficiency was greatly reduced.

[0111] It should be understood that the above embodiments are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims

1. A rapid separation method for measuring lithium isotopes in brine, characterized in that: The following steps are involved: S1. Filter the brine sample through a filter membrane; S2, pre-equilibration of cation separation column; S3, injecting the filtered brine sample into a cation separation column for separation; S4. After elution, the lithium-containing eluate is collected to achieve separation.

2. The method for rapid separation of lithium from brine according to claim 1, characterized in that: In step S1, a 0.45 μm filter membrane is used to filter the sample.

3. The method for rapid separation of lithium from brine according to claim 1, characterized in that: The cation separation column in step S2 is made of quartz, and the inner diameter of the resin-filled part of the separation column is 6-8 mm and the length is about 15-20 cm.

4. The method for rapid separation of lithium from brine according to claim 3, characterized in that: The cation separation column in step S2 uses a strongly acidic cation exchange resin selected from the group consisting of AG50W-X12 resin, AG50W-X8 resin, and AG MP 50 resin, or a combination of two or more thereof, with a particle size of 200-400 meshes.

5. The method for rapid separation of lithium from brine according to claim 4, characterized in that: In step S2, the cation exchange resin is pre-equilibrated with a dilute nitric acid alcohol solution; The dilute nitric acid alcohol solution is a mixture of nitric acid with a mass fraction of 60-63% and methanol solution with a volume ratio of 40-50wt% at 1:100-150.

6. The method for rapid separation of lithium from brine according to claim 1, characterized in that: The eluent used in the elution process in step S4 is an alcohol solution of nitric acid. The alcohol solution of nitric acid is a mixture of nitric acid with a mass fraction of 60-63% and methanol solution with a volume ratio of 80-90wt% at 1:10-20.

7. The method for rapid separation of lithium from brine according to claim 5 or 6, characterized in that: The alcohol solution is selected from C1-C4 alcohol solutions.

8. The rapid measurement method for lithium element in the rapid separation method of lithium element in brine according to any one of claims 1 to 7, characterized in that: The separated eluate is evaporated to dryness, a nitric acid solution is added and evaporated again, and the test solution obtained by dissolving with the nitric acid solution is used for detection.

9. The rapid measurement method according to claim 8, characterized in that: ICP-MS and ICP-OES were used to determine the contents of lithium and sodium in the brine samples after separation.

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