Method for detecting grafting rate of anion exchange resin and application thereof

Abstract

The invention provides a method for detecting the grafting rate of anion exchange resin, which is characterized by comprising the following steps: tabletting treatment: applying first pressure to a resin sample containing anion exchange resin, the pressure value of the first pressure being 15-45MPa, and thus preparing a tabletting sample; and grafting rate detection: carrying out X-ray fluorescence spectrum test on the tabletting sample, determining the content of characteristic elements in the tabletting sample, and calculating the grafting rate of the anion exchange resin based on the content of the characteristic elements. The characteristic elements are selected from at least one of elements contained in the anion exchange resin and elements introduced into the anion exchange resin after the anion exchange resin is pretreated. According to the scheme, on the basis of XRF detection, a certain pressure is applied to the resin sample before detection, the resin sample is tableted, and the obtained tableted sample is used for XRF detection, so that the accuracy of anion exchange resin grafting rate detection is improved to a great extent.

Description

Technical Field

[0001] The present invention belongs to the technical field of analytical chemistry, and specifically relates to a method for detecting the grafting rate of an anion exchange resin and its application. Background Art

[0002] Currently, the detection of the grafting rate of anion exchange membranes mostly uses titration methods in national standards (such as GB / T 5760-2000, GB / T 8144-2008, etc.). It is necessary to indirectly calculate the grafting rate by titrating the amount of unreacted acid / alkali after an ion exchange reaction. However, this method has the following defects:

[0003] 1. The operation is cumbersome, requiring multiple ion exchanges, filtrations, and titrations, and the detection period is as long as 3-5 days;

[0004] 2. The reagent consumption is large, generating waste liquid and having poor environmental friendliness;

[0005] 3. Affected by factors such as the concentration and temperature of the exchange solution, the result error is relatively large.

[0006] In addition, although there are grafting rate detection methods based on infrared spectroscopy in the prior art, due to the non-linear relationship between infrared absorption intensity and concentration, the accuracy of quantitative analysis is insufficient. Although X-ray fluorescence spectroscopy (XRF) technology has the advantages of rapidity and non-destructiveness, it does not combine the pretreatment steps for anion exchange resins, resulting in relatively high test errors.

[0007] Therefore, there is an urgent need for an efficient, environmentally friendly, and highly accurate detection method. Summary of the Invention

[0008] Based on X-ray fluorescence spectroscopy and by optimizing the pretreatment operation of samples, the present invention provides a method for detecting the grafting rate of an anion exchange membrane based on X-ray fluorescence spectroscopy and its application, significantly improving the detection efficiency and accuracy of the grafting rate of quaternary ammonium type anion exchange resins.

[0009] According to one aspect of the present invention, there is provided a method for detecting the grafting rate of an anion exchange resin, characterized by comprising the following steps:

[0010] Tabletting treatment: applying a first pressure to a resin sample containing an anion exchange resin, the pressure value of the first pressure being 15-45 MPa, thereby obtaining a tablet sample;

[0011] Grafting rate detection: performing X-ray fluorescence spectroscopy testing on the tablet sample, measuring the content of characteristic elements in the tablet sample, and calculating the grafting rate of the anion exchange resin based on the content of the characteristic elements. The characteristic elements are selected from at least one of the elements contained in the anion exchange resin itself and the elements introduced into the anion exchange resin through pretreatment of the anion exchange resin.

[0012] The above solution is based on XRF detection. Before detection, a certain pressure is applied to the resin sample to make tablets, and the obtained tablet samples are used for XRF detection, thereby greatly improving the accuracy of detecting the grafting rate of anion exchange resin. On the other hand, compared with the traditional method for testing the grafting rate of anion resin (such as the national standard titration method) which takes 3 to 4 days to complete the test, using the above solution to detect the grafting rate of anion resin can complete the treatment of resin samples and the grafting rate test within a few hours, significantly improving the detection efficiency. Moreover, the above method belongs to non-destructive detection. After the detection is completed, the resin samples can be recycled. The detection process does not require a large amount of test reagents, does not generate waste gas or waste liquid, reduces the material loss of detection, and is more in line with the concept of green environmental protection.

[0013] In the above solution, by measuring the content of characteristic elements in the tablet sample, the grafting rate of the resin sample can be calculated according to the following formula:

[0014] Grafting rate = (content of characteristic elements × 1000 / relative atomic mass of characteristic elements) × 100% / resin theoretical IEC. IEC refers to the ion exchange capacity, which is used to measure the ion replacement ability of materials (ion conduction ability of membranes). The calculation method of resin theoretical IEC is the reciprocal of the resin monomer molecular weight multiplied by 1000.

[0015] Preferably, in the tablet pressing process, the pressure value of the first pressure is 20 - 40 MPa. The first pressure can be 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, etc., but is not limited to the listed values. Other unlisted values within this numerical range are also applicable.

[0016] Preferably, in the tablet pressing process, the pressure holding time of the first pressure is not less than 10 seconds.

[0017] Preferably, in the tablet pressing process, the pressure holding time of the first pressure is 10 - 30 seconds. The pressure holding time of the first pressure can be 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, etc., but is not limited to the listed values. Other unlisted values within this numerical range are also applicable.

[0018] Preferably, in each tablet pressing process, the mass of the resin sample to be processed is 1 g - 2 g.

[0019] Preferably, the method further includes a step of sample washing. In the step of sample washing, the resin sample is washed successively with an organic solvent and water; after the sample washing of the resin sample is completed, the resin sample is then subjected to tablet pressing.

[0020] Preferably, the organic solvent includes at least one of alcohol solvents, ether solvents, and halogenated hydrocarbon solvents.

[0021] Preferably, the alcohol solvent includes at least one of acetone, methanol, ethanol, and isopropyl alcohol. Preferably, the ether solvent includes diethyl ether.

[0022] Preferably, the halogenated hydrocarbon solvent includes dichloromethane.

[0023] Preferably, the organic solvent includes ethanol. Since ethanol has strong dissolving ability and is volatile, it can not only wash away the impurities in the sample but also will not remain in the sample. In addition, it also has the advantages of low cost and environmental protection.

[0024] Preferably, the characteristic element is selected from at least one of halogens. The X-ray energy of the halogen characteristic is higher and it is less affected by the matrix effect and environmental interference. Therefore, selecting halogen as the characteristic element is beneficial to improving the accuracy of XRF detection.

[0025] According to the second aspect of the present invention, there is provided an application of the above method for detecting the grafting rate of an anion resin in evaluating the exchange capacity of an anion exchange membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a physical diagram of the tablet sample prepared by tablet pressing in each Example 1;

[0027] Figure 2 It is a statistical chart of the test results of the grafting rate of PQAPPT resin measured by the XRF test method and the national standard titration method in Example 1 respectively;

[0028] Figure 3 It is a statistical chart of the test results of the grafting rate of PQAPPT resin measured by the XRF test method and the national standard titration method in Example 5 respectively;

[0029] Figure 4 is It is a physical diagram of the film-shaped resin sample used for XRF test in the control group D1-2 of Comparative Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0031] Example 1

[0032] In this example, PQAPPT resin is used as the test object to determine the grafting rate of PQAPPT resin. The molecular monomer structure of PQAPPT resin is as follows: In this structural general formula, A represents p-terphenyl.

[0033] S1. Sample washing

[0034] S1-1. Immerse the resin sample in 500 mL of ethanol, place it in a 50 °C constant-temperature magnetic stirrer for 1 hour and then filter. Repeat this process 3 times to complete the first washing.

[0035] S1-2. Then immerse the resin sample in 500 mL of pure water (RO water), place it in a 50 °C constant-temperature magnetic stirrer for 1 hour and then filter. Repeat this process 3 times to complete the second washing.

[0036] S1-3. After the above washing operations are completed, place the resin sample in an 80 °C oven for drying. The drying time is about 4 hours.

[0037] S2. Tablet pressing

[0038] S2-1. Take 5 g of the dried resin sample and screen the resin sample with a 200-mesh sieve.

[0039] S2-2. Take 2 g of the screened resin sample and pour it into the tablet press mold (between two metal gaskets). Place the mold in the middle of the hydraulic table. First, tighten the screw clockwise to fix the mold. Then, tighten the pressure relief valve (black valve) clockwise and shake the handle lever back and forth to reach the required pressure value, which is recorded as the first pressure. In this embodiment, the first pressure is 30 MPa, and the pressure holding time of the first pressure is 15 seconds. Thus, the resin sample is made into a tablet sample.

[0040] S2-3. Unscrew the pressure relief valve counterclockwise. After the pressure drops to atmospheric pressure, demold and take out the tablet sample. The schematic diagram of the tablet sample is as Figure 1 shown.

[0041] S3. Grafting rate test

[0042] S3-1. Use an X-ray fluorescence spectrometer (NITON XL2 Plus) as the detection device. Open the protective cover of the device, place the tablet sample on the detection window, ensure that the tablet sample completely covers the test window, and then gently close the protective cover.

[0043] S3-2. After completing S3-1, click "Start Detection" on the control interface of the device. The device starts testing. After about 20 seconds, the device will automatically make a sound to remind that the test is completed. Record the content of the characteristic element (the characteristic element in this embodiment is the Br element) on the main interface of the host. Then, according to the above operation, start the detection process again to conduct the second test. Repeat the test 5 times. To ensure accurate results, after completion, turn the tablet sample over and conduct 5 more tests and record the results.

[0044] S3-3. Calculate the grafting rate of the tested anion exchange resin based on the measured content of the characteristic element. The data processing method of the test results is as follows:

[0045] a. Control the range of the test data of the single-sided site for 5 times ≤ 0.95% (corresponding to a grafting rate of 5%). If it exceeds this value, the maximum and minimum values must be eliminated and retested.

[0046] b. Take the average of the data on both sides as the final content of Br element in a single sample

[0047] c. Substituting the Br element content into the following formula, the grafting rate of the resin sample can be calculated:

[0048] Grafting rate = (characteristic element content × 1000 / relative atomic mass of characteristic element) × 100% / resin theoretical IEC

[0049] =(Br element content × 1000 / 80) × 100% / 2.23

[0050] In this example, 19 batches of PQAPPT resin were tested for grafting rate according to the above operation (XRF test method), and the time taken for each resin sample from sample processing to test completion was about 5 hours. As a control, the grafting rate of the PQAPPT resin tested in this example was tested by precipitation titration after ion exchange (national standard titration method), and the time taken for each resin sample from sample processing to test completion was about 3 to 4 days. The comparison of the above test results is shown in Figure 2. Figure 2 As shown, in Figure 2 In the figure, the horizontal axis represents the batch number of the PQAPPT resin tested, the vertical axis represents the grafting rate, and the blue trend line represents the grafting rate of different batches of PQAPPT resin measured by the XRF test method of Example 1, and the orange trend line represents the grafting rate of different batches of PQAPPT resin measured by the national standard titration method. It can be seen that the change trends of the grafting rates of different batches of PQAPPT resin measured by the two different test methods are basically the same. The average grafting rate of 19 batches of PQAPPT resin tested by the national standard titration method is 93%, while The average grafting rate of 19 batches of the PQAPPT resin tested by the XRF test method was 90%. Based on the above test results, the test error of the XRF test method used in this embodiment was calculated as follows: the average grafting rate of the PQAPPT resin tested by the national standard titration method involved in this implementation was used as a standard control, and the absolute value of the difference between the average grafting rate of the PQAPPT resin tested by the national standard titration method and the average grafting rate of the PQAPPT resin tested by the XRF test method in this embodiment was calculated as the test error. Thus, it was calculated that the test error corresponding to the test result of the XRF test method used in this embodiment was 3%, indicating that the test result had a high degree of consistency.

[0051] Example 2

[0052] Regarding the selection of the test object, this embodiment is the same as that of Embodiment 1. In this embodiment, the PQAPPT resin of the same batch as the 19 batches of PQAPPT resin selected in Embodiment 1 (a total of 19 batches) is used as the test object to measure the grafting rate of the PQAPPT resin.

[0053] In this embodiment, the PQAPPT resin is used as the resin sample. Referring to Embodiment 1, the measurement of the grafting rate of the resin sample is completed. In this embodiment, during the process of tablet pressing the resin sample, the magnitude of the first pressure applied to the resin sample is used as a variable, and different treatment groups are set, which are respectively labeled as Treatment Group 2-1, Treatment Group 2-2, Treatment Group 2-3, and Treatment Group 2-4. The specific settings of the above treatment groups are as follows.

[0054] Treatment Group 2-1: Regarding the step operations for measuring the grafting rate of the resin sample, Treatment Group 2-1 also includes steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Embodiment 1 is that during the process of tablet pressing the resin sample, the magnitude of the first pressure is adjusted to 15 MPa. Except for the above difference, the steps and operations performed by Treatment Group 2-1 to measure the grafting rate of the resin sample are strictly consistent with the corresponding content of Embodiment 1.

[0055] Treatment Group 2-2: Regarding the step operations for measuring the grafting rate of the resin sample, Treatment Group 2-2 also includes steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Embodiment 1 is that during the process of tablet pressing the resin sample, the magnitude of the first pressure is adjusted to 20 MPa. Except for the above difference, the steps and operations performed by Treatment Group 2-2 to measure the grafting rate of the resin sample are strictly consistent with the corresponding content of Embodiment 1.

[0056] Treatment Group 2-3: Regarding the step operations for measuring the grafting rate of the resin sample, Treatment Group 2-3 also includes steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Embodiment 1 is that during the process of tablet pressing the resin sample, the magnitude of the first pressure is adjusted to 40 MPa. Except for the above difference, the steps and operations performed by Treatment Group 2-3 to measure the grafting rate of the resin sample are strictly consistent with the corresponding content of Embodiment 1.

[0057] To compare the differences in the test accuracy of the PQAPPT resin grafting rate between each treatment group in this example and Example 1, Table 1 shows the average grafting rates of the tested PQAPPT resins measured by the grafting rate test methods used in Example 1 and each treatment group in this example. The average grafting rate of the tested PQAPPT resin measured by the national standard titration method involved in Example 1 was used as the standard control to calculate the test error: Calculate the absolute value of the difference between the average grafting rate of the tested PQAPPT resin measured by the national standard titration method and the average grafting rate of the tested PQAPPT resin measured by the XRF test method, and use this as the test error.

[0058] From the test results, it can be seen that when using the XRF test method to test the grafting rate of resin samples, during the tablet pressing process in the sample treatment stage, the magnitude of the first pressure applied to the resin samples will affect the test results. In the process of tablet pressing, the first pressure applied to the resin samples by Treatment Group 2-1 in Example 2 was too small, resulting in a relatively small density of the tablet samples, with certain gaps. The relatively small density would cause the average grafting rate of the PQAPPT resin measured by this treatment group to be on the low side. Compared with Treatment Group 2-3 in Example 2, Example 1, Treatment Group 2-1 in Example 2, and Treatment Group 2-2 in Example 2 all used a higher first pressure to prepare the tablet samples, so that the average grafting rates of the PQAPPT resin measured by these groups were more accurate and the test errors were lower.

[0059] Table 1. Statistical situation of test errors of each treatment group in Example 1 and Example 2

[0060]

[0061] Example 3

[0062] Regarding the selection of test objects, this example is the same as Example 1. In this example, 19 batches of PQAPPT resins of the same batch as the 19 batches of PQAPPT resins selected in Example 1 were used as test objects to measure the grafting rate of the PQAPPT resins.

[0063] In this example, PQAPPT resin was used as the resin sample. Referring to Example 1, the determination of the grafting rate of the resin sample was completed. In this example, the specific operations involved in the sample washing process of the resin sample were used as variables, and different treatment groups were set, which were respectively labeled as Treatment Group 3-1, Treatment Group 3-2, Treatment Group 3-3, Treatment Group 3-4, and Treatment Group 3-5. The specific settings of the above treatment groups are as follows.

[0064] Treatment Group 3-1: Regarding the procedure for measuring the grafting rate of the resin sample, the difference from Example 1 is that Treatment Group 3-1 omitted the step of sample washing. Except for the above difference, the steps and operations performed by Treatment Group 3-1 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0065] Treatment Group 3-2: Regarding the procedure for measuring the grafting rate of the resin sample, Treatment Group 3-2 also included steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Example 1 is that in the step of sample washing of the resin sample, Treatment Group 3-2 omitted the operation of the first washing (i.e., directly omitted S1-1 of Example 1 and did not use organic solvent for washing), and only used RO water to complete the washing of the resin sample according to S1-2 of Example 1 in the step of sample washing. Except for the above difference, the steps and operations performed by Treatment Group 3-2 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0066] Treatment Group 3-3: Regarding the procedure for measuring the grafting rate of the resin sample, Treatment Group 3-3 also included steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Example 1 is that in the step of sample washing of the resin sample, Treatment Group 3-3 omitted the operation of the second washing (i.e., directly omitted S1-2 of Example 1 and did not use RO water for washing), and only used ethanol to complete the washing of the resin sample according to S1-1 of Example 1 in the step of sample washing. Except for the above difference, the steps and operations performed by Treatment Group 3-3 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0067] Treatment Group 3-4: Regarding the procedure for measuring the grafting rate of the resin sample, Treatment Group 3-4 also included steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Example 1 is that in S1-1 of the sample washing of the resin sample, Treatment Group 3-4 used ether instead of ethanol as the organic solvent for the first washing of the resin sample. Except for the above difference, the steps and operations performed by Treatment Group 3-4 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0068] Treatment Group 3-5: Regarding the procedure for measuring the grafting rate of the resin sample, Treatment Group 3-5 also included steps such as sample washing, tablet pressing, and grafting rate testing. The difference from Example 1 is that in S1-1 of the sample washing of the resin sample, Treatment Group 3-5 used dichloromethane instead of ethanol as the organic solvent for the first washing of the resin sample. Except for the above difference, the steps and operations performed by Treatment Group 3-5 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0069] To compare the differences in the test accuracy of the PQAPPT resin grafting rate between each treatment group in this example and Example 1, Table 2 shows the average grafting rates of the tested PQAPPT resins measured by the grafting rate test methods used in Example 1 and each treatment group in this example, respectively. Taking the average grafting rate of the tested PQAPPT resin measured by the national standard titration method involved in Example 1 as the standard control, the test error was calculated: Calculate the absolute value of the difference between the average grafting rate of the tested PQAPPT resin measured by the national standard titration method and the average grafting rate of the tested PQAPPT resin measured by the XRF test method, and use this as the test error.

[0070] From the test results, it can be seen that when using the XRF test method to test the grafting rate of resin samples, during the sample treatment stage, the washing treatment of resin samples will affect the test results. Specifically, by sequentially washing the resin samples with ethanol and RO water, the impurities in the resin samples can be better removed, making the test results more accurate.

[0071] Table 2. Statistical situation of test errors for each treatment group in Example 1 and Example 3

[0072]

[0073] Comparative Example 1

[0074] Regarding the selection of the test object, it is the same as that in Example 1. In this comparative example, 19 batches of PQAPPT resins of the same batch as those selected in Example 1 (a total of 19 batches) were used as the test objects to measure the grafting rate of PQAPPT resins.

[0075] In this comparative example, PQAPPT resin was used as the resin sample. Referring to Example 1, the determination of the grafting rate of the resin sample was completed. In this comparative example, the sample preparation operation of the resin sample was used as a variable, and different control groups were set, which were respectively marked as Control Group D1-1 and Control Group D1-2. The specific settings of the above control groups are as follows.

[0076] Control Group D1-1: Regarding the step operation for determining the grafting rate of the resin sample, the difference from Example 1 is that Control Group D1-1 directly replaced S2 (tabletting treatment step) involved in Example 1 with the following operation: First, sieve the powdery resin through a 200-mesh sieve to obtain a powdery resin sample, and then pour 2 g - 3 g of the above powdery resin sample into a sample cup with an inner diameter of 2 cm for subsequent grafting rate tests. Except for the above differences, the steps and operations performed by Control Group D1-1 to determine the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0077] Control group D1-2: Regarding the procedure for measuring the grafting rate of the resin sample, the difference from Example 1 is that in Control group D1-2, S2 (the tablet pressing treatment step) involved in Example 1 is directly replaced with the following operation: The following operation: Dissolve the powdery resin in DMSO, then cast and dry it to obtain a resin film with a thickness of about 75 μm. Then cut the resin film into square film pieces of 1.5 cm × 1.5 cm. Then stack multiple layers of square film pieces to a composite film piece with a total thickness of about 4 mm, and press the composite film piece to obtain a film-shaped resin sample (as as shown in Figure 4 shown), and use the film-shaped resin sample obtained after the above operation for subsequent grafting rate tests. Except for the above differences, the steps and operations performed by Control group D1-2 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 1.

[0078] To compare the differences in the test accuracy of the grafting rate of PQAPPT resin between each control group of this comparative example and Example 1, Table 3 shows the average grafting rates of the tested PQAPPT resins measured by the grafting rate test methods used in Example 1 and each control group of this comparative example respectively, and uses the average grafting rate of the tested PQAPPT resin measured by the national standard titration method involved in Example 1 as the standard control to calculate the test error: Calculate the absolute value of the difference between the average grafting rate of the tested PQAPPT resin measured by the national standard titration method and the average grafting rate of the tested PQAPPT resin measured by the XRF test method, and use this as the test error.

[0079] After calculation, the test error of the test result obtained by using the test method of Control group D1-1 is 19%, and the test error of the test result obtained by using the test method of Control group D1-2 is 25%. It can be clearly seen that the test error corresponding to the test method used in this comparative example is significantly greater than the test error corresponding to the XRF test method used in Example 1.

[0080] From the test results, it can be seen that using the XRF test method to test the grafting rate of the resin sample has a significant impact on the sample preparation method of the resin sample. Specifically, Control group D1-1 uses a powdery resin sample for XRF detection, while Control group D1-2 uses a film-shaped resin sample for XRF detection. The average grafting rates of the PQAPPT resins measured by these two control groups are significantly lower, and there is a relatively large error in the test results, making it difficult to accurately measure the average grafting rate of the PQAPPT resin. However, Example 1 uses a tablet sample for XRF detection, and its corresponding test error is reduced to a relatively small range, and it can accurately measure the average grafting rate of the PQAPPT resin.

[0081] Table 3. Statistical situation of test errors of Example 1 and each control group of Comparative Example 1

[0082]

[0083]

[0084] Example 4

[0085] In this example, QAMPPT resin was used as the test object to determine the grafting rate of QAMPPT resin. The molecular monomer structure of QAMPPT resin is as follows: In this structural general formula, A represents m-terphenyl.

[0086] S0. Pretreatment

[0087] 5 g of QAMPPT resin was loaded into 500 mL of a KBr solution with a concentration of 1 mol / L, and the above solution was stirred with a constant-temperature magnetic stirrer at 80 °C. During this process, ion exchange occurred between QAMPPT resin and KBr. The above reaction conditions were maintained for 1 hour, and then the solution was filtered to retain the resin sample. The ion exchange was repeated 3 times according to the above operation.

[0088] S1. Sample washing

[0089] S1-1. The resin sample after ion exchange was loaded into 500 mL of ethanol and soaked. After being placed in a constant-temperature magnetic stirrer at 50 °C for 1 hour, it was filtered, and this was repeated 3 times to complete the first washing.

[0090] S1-2. Then the resin sample was put into 500 mL of pure water (RO water) and soaked. After being placed in a constant-temperature magnetic stirrer at 50 °C for 1 hour, it was filtered, and this was repeated 3 times to complete the second washing.

[0091] S1-3. After the above washing operation was completed, the resin sample was placed in an oven at 80 °C for drying, and the drying time was about 4 hours.

[0092] S2. Tablet pressing treatment

[0093] S2-1. Take 5 g of the dried resin sample and screen the resin sample with a 200-mesh sieve;

[0094] S2-2. Take 2 g of the screened resin sample and pour it into the tablet press mold (between two metal gaskets). Place the mold in the middle of the hydraulic table. First, tighten the screw rod clockwise to fix the mold. Then, tighten the pressure relief valve (black valve) clockwise and shake the handle of the pressure bar back and forth to reach the required pressure value, which is recorded as the first pressure. In this example, the first pressure is 30 MPa, and the pressure holding time of the first pressure is 15 seconds, thereby making the resin sample into a tablet sample.

[0095] S2-3. Unscrew the pressure relief valve counterclockwise and demold to take out the tablet sample.

[0096] S3. Grafting rate test

[0097] The operation in this step is consistent with the grafting rate test in Example 1. In this step, Br element is still used as the characteristic element. Based on this, substituting the content of Br element observed in this example into the following formula, the grafting rate of the resin sample can be calculated:

[0098] Grafting rate = (content of characteristic element × 1000 / relative atomic mass of characteristic element) × 100% / resin theoretical IEC

[0099] = (content of Br element × 1000 / 80) × 100% / 2.38

[0100] In this example, the grafting rate tests were carried out on 17 batches of QAMPPT resins respectively according to the above operation (XRF test method). The time taken from sample treatment to test completion for each resin sample was about 6 hours. As a control, for the QAMPPT resins participating in this example, the grafting rate test was correspondingly carried out by the method of precipitation titration after ion exchange (national standard titration method). The time taken from sample treatment to test completion for each resin sample was about 5 - 7 days. The comparison of the above test results is as Figure 3 shown. In Figure 3 , the abscissa represents the batch numbers of the participating QAMPPT resins, the ordinate represents the grafting rate, and the blue trend line represents the grafting rates of different batches of QAMPPT resins measured by the XRF test method in Example 5, and the orange trend line represents the grafting rates of different batches of QAMPPT resins measured by the national standard titration method. It can be seen that the change trends of the grafting rates of different batches of QAMPPT resins measured by the two different test methods are basically the same. The average grafting rate of the 17 batches of participating QAMPPT resins measured by the national standard titration method is 87%, while the average grafting rate of the 17 batches of participating QAMPPT resins measured by the XRF test method is 83%. Based on the above test results, calculate the test error of the XRF test method adopted in this example according to the following method: taking the average grafting rate of the participating QAMPPT resins measured by the national standard titration method involved in this example as the standard control, calculate the absolute value of the difference between the average grafting rate of the participating QAMPPT resins measured by the national standard titration method and the average grafting rate of the participating QAMPPT resins measured by the XRF test method in this example, and take this as the test error. Thus, the test error corresponding to the test result of the XRF test method adopted in this example is calculated to be 4%, indicating a high degree of coincidence of the test results.

[0101] Example 5

[0102] Regarding the selection of the test objects, this embodiment is the same as that of Embodiment 4. In this embodiment, the QAMPPT resin of the same batch as the 17 batches of QAMPPT resin selected in Embodiment 4 (a total of 17 batches) is used as the test object to measure the grafting rate of the QAMPPT resin.

[0103] In this embodiment, the QAMPPT resin is used as the resin sample. Referring to Embodiment 4, the measurement of the grafting rate of the resin sample is completed. The difference from Embodiment 4 is that in the step of pre-treating the QAMPPT resin, a KCl solution with the same concentration is used to replace the KBr solution used in Embodiment 4 to perform ion exchange with the tested QAMPPT resin. In the subsequent grafting rate test step, Cl element is used as the characteristic element, and the grafting rate of the sample is calculated based on the Cl element content measured by XRF. Except for the above differences, the steps and operations performed to measure the grafting rate of the resin sample in this embodiment are strictly consistent with the corresponding content of Embodiment 4.

[0104] Based on the selected characteristic element, the grafting rate of the resin sample is calculated according to the following formula in this embodiment: Grafting rate = (Characteristic element content × 1000 / Relative atomic mass of the characteristic element) × 100% / Resin theoretical IEC

[0105] = (Cl element content × 1000 / 35.5) × 100% / 2.23

[0106] In this embodiment, the average grafting rate of the 17 batches of tested QAMPPT resin measured by the XRF test method is 81%. Taking the average grafting rate of the tested QAMPPT resin measured by the national standard titration method involved in Embodiment 4 as the standard control, the test error is calculated: Calculate the absolute value of the difference between the average grafting rate of the tested QAMPPT resin measured by the national standard titration method and the average grafting rate of the tested QAMPPT resin measured by the XRF test method in this embodiment, and use this as the test error. Thus, the test error corresponding to the test result of the XRF test method used in this embodiment is calculated to be 6%, indicating a high degree of coincidence of the test results.

[0107] Comparative Example 2

[0108] Regarding the selection of the test objects, this comparative example is the same as that of Embodiment 4. In this comparative example, the QAMPPT resin of the same batch as the 17 batches of QAMPPT resin selected in Embodiment 4 (a total of 17 batches) is used as the test object to measure the grafting rate of the QAMPPT resin.

[0109] In this comparative example, QAMPPT resin was used as the resin sample. Referring to Example 4, the grafting rate of the resin sample was determined. In this comparative example, the sample preparation operation on the resin sample was used as a variable, and different control groups were set up, which were respectively labeled as Control Group D2-1 and Control Group D2-2. The specific settings of the above control groups are as follows.

[0110] Control Group D2-1: Regarding the step operation for measuring the grafting rate of the resin sample, the difference from Example 4 is that Control Group D2-1 directly replaced S2 (tabletting treatment step) involved in Example 4 with the following operation: First, sieve the powdery resin through a 200-mesh sieve to obtain a powdery resin sample. Then, pour 2 g to 3 g of the above powdery resin sample into a sample cup with an inner diameter of 2 cm, and perform subsequent grafting rate tests. Except for the above differences, the steps and operations performed by Control Group D2-1 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 4.

[0111] Control Group D2-2: Regarding the step operation for measuring the grafting rate of the resin sample, the difference from Example 4 is that Control Group D2-2 directly replaced S2 (tabletting treatment step) involved in Example 4 with the following operation: Dissolve the powdery resin in DMSO and then cast and dry it to obtain a resin film with a thickness of about 75 μm. Then, cut the resin film into square film pieces with a size of 1.5 cm × 1.5 cm. Then, stack multiple square film pieces to a composite film piece with a total thickness of about 4 mm, and press the composite film piece to obtain a film-shaped resin sample (similar to Figure 4 type ), and perform subsequent grafting rate tests on the film-shaped resin sample obtained after the above operation. Except for the above differences, the steps and operations performed by Control Group D2-2 for measuring the grafting rate of the resin sample are strictly consistent with the corresponding content of Example 4.

[0112] To compare the differences in the test accuracy of the grafting rate of QAMPPT resin between each control group in this comparative example and Example 4, Table 4 shows the average grafting rates of the tested QAMPPT resins measured by the grafting rate test methods adopted in Example 4 and each control group in this comparative example, and uses the average grafting rate of the tested QAMPPT resin measured by the national standard titration method involved in Example 4 as the standard control to calculate the test error: Calculate the absolute value of the difference between the average grafting rate of the tested QAMPPT resin measured by the national standard titration method and the average grafting rate of the tested QAMPPT resin measured by the XRF test method, and use this as the test error.

[0113] After calculation, the test error of the test results obtained by using the test method of control group D2-1 is 21%, and the test error of the test results obtained by using the test method of control group D2-2 is 34%. It can be clearly seen that the test error corresponding to the test method adopted in this comparative example is significantly greater than the test error corresponding to the XRF test method adopted in Example 4.

[0114] Table 4. Statistical situation of test errors of each control group in Example 4 and Comparative Example 2

[0115]

[0116] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced, but these modifications or replacements are all within the protection scope of the present invention.

Claims

1. A method for detecting the grafting rate of an anion exchange resin, characterized in that It includes the following steps: Tabletting treatment: Apply a first pressure to a resin sample containing an anion exchange resin, where the pressure value of the first pressure is 15 - 45 MPa, thereby obtaining a tablet sample; Grafting rate detection: Conduct an X-ray fluorescence spectroscopy test on the tablet sample, determine the content of characteristic elements in the tablet sample, and calculate the grafting rate of the anion exchange resin based on the content of the characteristic elements. The characteristic elements are selected from at least one of the elements contained in the anion exchange resin itself and the elements introduced into the anion exchange resin through pretreatment of the anion exchange resin.

2. The method for detecting the grafting rate of an anion exchange resin according to claim 1, wherein In the tabletting treatment, the pressure value of the first pressure is 20 - 40 MPa.

3. The method for detecting the grafting rate of an anion exchange resin according to claim 1, characterized in that In the tabletting treatment, the pressure holding time of the first pressure is 10 - 30 seconds.

4. The method for detecting the grafting rate of an anion exchange resin according to claim 1, characterized in that, In each tabletting treatment, the mass of the resin sample being treated is 1 g - 2 g.

5. The method for detecting the grafting rate of an anion exchange resin according to claim 1, characterized in that: The method further includes a step of sample washing. In the step of sample washing, the resin sample is washed successively with an organic solvent and water; After completing the sample washing of the resin sample, the resin sample is then subjected to the tabletting treatment.

6. The method for detecting the grafting rate of an anion exchange resin according to claim 5, wherein: The organic solvent includes at least one of alcohol solvents, ether solvents, and halogenated hydrocarbon solvents.

7. The method for detecting the grafting rate of an anion exchange resin according to claim 6, characterized in that: When the organic solvent includes the alcohol solvent, the alcohol solvent includes at least one of acetone, methanol, ethanol, and isopropanol; When the organic solvent includes the ether solvent, the ether solvent includes diethyl ether; When the organic solvent includes the halogenated hydrocarbon solvent, the halogenated hydrocarbon solvent includes dichloromethane.

8. The method for detecting the grafting rate of an anion exchange resin according to claim 6, characterized in that: The organic solvent includes ethanol.

9. The method for detecting the grafting rate of an anion exchange resin according to claim 1, characterized in that: The characteristic elements are selected from at least one of halogens.

10. The application of the method for detecting the grafting rate of an anion resin according to any one of claims 1 - 9 in evaluating the exchange capacity of an anion exchange membrane.

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