Method for detecting ionic degree of cationic polyacrylamide

Abstract

The invention discloses a method for detecting the ionic degree of cationic polyacrylamide. The detection method comprises the following steps: preparing a cationic polyacrylamide solution with a preset concentration; a sensor probe of a charge analyzer is placed in the cationic polyacrylamide solution, and a standard titration solution of poly (2-acrylamide-2-methylpropanesulfonic acid) potassium is dropped into the cationic polyacrylamide solution at a preset stirring speed until the SCV value of the charge analyzer is 0. And obtaining the titration volume of the potassium 2-acrylamide-2-methylpropanesulfonate standard titration solution dripped into the cationic polyacrylamide solution. And calculating the ionic degree of cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume. Compared with a mode of recognizing a titration end point by human eyes of a worker, the detection method has higher detection accuracy and repeatability.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer detection, and particularly to a method for detecting the ionic degree of cationic polyacrylamide. Background Art

[0002] Due to its unique cationic properties, cationic polyacrylamide exhibits excellent efficacy in multiple fields such as water treatment, papermaking, mining, and oil extraction. In water treatment, it can efficiently flocculate suspended impurities in water to purify the water; in the paper industry, it can help enhance the strength and improve the evenness of paper; in the mining field, it helps in the sedimentation and separation of tailings, reducing the risk of environmental pollution; during oil extraction, it is used in the preparation of drilling fluids and fracturing fluids to improve the extraction efficiency.

[0003] However, there are many drawbacks in the current traditional methods for determining the ionic degree of cationic polyacrylamide. The most common one is relying on the staff to observe the titration end point with the naked eye, which is highly subjective. The experience levels of the operators vary, and long-term visual observation is extremely prone to visual fatigue, thus leading to judgment errors. In addition, due to the different sensitivities and cognitions of different personnel to the color change at the titration end point, the detection results often fluctuate greatly, unable to provide accurate and reliable data support for the actual application of cationic polyacrylamide, restricting its further optimal performance in various fields. Summary of the Invention

[0004] Based on the above problems, the present invention provides a method for detecting the ionic degree of cationic polyacrylamide. Compared with the method of the staff identifying the titration end point with the human eye, this detection method has higher detection accuracy.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for detecting the ionic degree of cationic polyacrylamide, characterized by comprising the following steps:

[0007] Step 1: Prepare a cationic polyacrylamide solution with a preset concentration;

[0008] Step 2: Place the sensor probe of the charge analyzer into the cationic polyacrylamide solution, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant into the cationic polyacrylamide solution at a preset stirring speed until the SCV value of the charge analyzer is 0;

[0009] Step 3: Obtain the titration volume of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution;

[0010] Step 4: Calculate the ionic degree of the cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume.

[0011] In some embodiments, the preset concentration is 4 mg / L to 10 mg / L.

[0012] In some embodiments, the preset stirring speed is 300 rpm to 600 rpm.

[0013] In some embodiments, the charge analyzer includes a controller, and the controller is configured to control the stop of dropping the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant when the SCV value of the charge analyzer is 0.

[0014] In some embodiments, in Step 2, the sensor probe of the charge analyzer is placed in the cationic polyacrylamide solution, and after the SCV value of the charge analyzer remains unchanged at the preset stirring speed, the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant is started to be dropped into the cationic polyacrylamide solution.

[0015] In some embodiments, after the SCV value of the charge analyzer remains unchanged for more than 5 s at the preset stirring speed, the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant is started to be dropped into the cationic polyacrylamide solution.

[0016] In some embodiments, configuring the cationic polyacrylamide solution with the preset concentration includes the following steps:

[0017] Weigh cationic polyacrylamide with a mass of m, and add a solvent to obtain a first solution with a volume of V;

[0018] Pipette a volume of V 1 of the first solution, and add a solvent to obtain the cationic polyacrylamide solution with the preset concentration, where V 1 < V.

[0019] In some embodiments, obtaining the titration volume of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution includes the following steps:

[0020] Record the volume V 2 ;

[0021] Obtain a solvent with a preset volume, where the preset volume is equal to the volume of the cationic polyacrylamide solution, and the solvent is the solvent in the cationic polyacrylamide solution;

[0022] Place the sensor probe of the charge analyzer into the solvent with the preset volume, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant into the solvent with the preset volume at the preset stirring speed until the SCV value of the charge analyzer is 0; record the volume V of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the solvent with the preset volume when the SCV value of the charge analyzer is 0 0 ;

[0023] The titration volume is equal to V 2 -V 0 。

[0024] In some embodiments, calculating the ionic degree of the cationic polyacrylamide in the cationic polyacrylamide solution based on the titration volume includes calculating the ionic degree according to formula (1):

[0025]

[0026] where n = (V 2 -V 0 )c×10 -3 ;

[0027] n represents the number of moles of acryloyloxyethyltrimethylammonium chloride cationic monomer, with the unit of mol;

[0028] The unit of m is g;

[0029] w 1 represents the solid content of the cationic polyacrylamide, with the unit of %;

[0030] V 0 has the unit of mL;

[0031] V 1 has the unit of mL;

[0032] V 2 has the unit of mL;

[0033] M 1 represents the molar mass of acryloyloxyethyltrimethylammonium chloride cationic monomer, M 1 is 193.67 g / mol;

[0034] M 2 represents the molar mass of acrylamide monomer, M 2 is 71.08 g / mol;

[0035] c represents the molar concentration of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant, with the unit of mol / L;

[0036] The unit of w is %.

[0037] In some of these embodiments, the solvent of the cationic polyacrylamide solution is water.

[0038] Beneficial effects

[0039] A method for detecting the ionic degree of a cationic polyacrylamide in the present invention configures a cationic polyacrylamide solution with a preset concentration. Place the sensor probe of the charge analyzer into the cationic polyacrylamide solution, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant into the cationic polyacrylamide solution under stirring conditions until the SCV value of the charge analyzer is 0. Obtain the titration volume of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution. Calculate the ionic degree of the cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume. Compared with the way that staff identify the titration end point by eyes, this detection method can more accurately determine the titration end point, and has higher detection accuracy and repeatability. Description of the drawings

[0040] Figure 1 It is a flowchart of the method for detecting the ionic degree of a cationic polyacrylamide in an embodiment of the present invention. Detailed implementation manners

[0041] Please refer to Figure 1 , an embodiment of the present invention provides a method for detecting the ionic degree of a cationic polyacrylamide. The method for detecting the ionic degree of a cationic polyacrylamide includes the following steps:

[0042] Step 1: Configure a cationic polyacrylamide solution with a preset concentration.

[0043] Step 2: Place the sensor probe of the charge analyzer into the cationic polyacrylamide solution, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) (PAMPSK) standard titrant into the cationic polyacrylamide solution at a preset stirring speed until the SCV value of the charge analyzer is 0.

[0044] Step 3: Obtain the titration volume of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution.

[0045] Step 4: Calculate the ionic degree of the cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume.

[0046] When detecting the ionic degree of cationic polyacrylamide by using the method in this embodiment, the titration end point can be determined according to the SCV value of the charge analyzer. An SCV value of 0 indicates the titration end point. At this time, stop dropping the PAMPSK standard titrant into the cationic polyacrylamide solution, so that the titration volume of the PAMPSK standard titrant dropped into the cationic polyacrylamide solution can be accurately obtained. Then, calculate the ionic degree of the cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume. Compared with the way that the staff identifies the titration end point by eyes, this detection method has higher detection accuracy and repeatability.

[0047] It can be understood that when using the charge analyzer, turn on the charge analyzer and perform a preheating operation in advance. The preheating time is not less than 10 minutes to ensure that the instrument reaches a stable working state and all performance indicators meet the detection requirements. Carefully and vertically insert the calibrated sensor probe into the prepared cationic polyacrylamide solution, and keep the insertion depth consistent, usually at one-third to one-half of the solution depth. At the same time, ensure that the probe does not touch the container wall to avoid interference signals generated by collision affecting the measurement accuracy.

[0048] In some embodiments, the preset concentration is 4mg / L to 10mg / L. Prepare the cationic polyacrylamide solution within this preset concentration range. Within this preset concentration range, the charge analyzer can obtain more accurate results, further improving the accuracy of the detection method for the ionic degree of cationic polyacrylamide. Optionally, the preset concentration can be 4mg / L, 5mg / L, 6mg / L, 7mg / L, 8mg / L, 9mg / L, 10mg / L, etc. It can be understood that the preset concentration can also be other suitable selections within the range of 4mg / L to 10mg / L.

[0049] In some embodiments, the preset stirring speed is 300rpm to 600rpm. This stirring speed range can not only promote the rapid and uniform mixing of the solution to ensure that the PAMPSK standard titrant can quickly and fully react with the cationic polyacrylamide solution after being dropped in, but also effectively prevent too many bubbles from being introduced due to overly violent stirring. Too many bubbles will not only interfere with the sensor probe's perception of the charge state of the solution, but also may change the actual volume of the solution, thus causing deviation in the judgment of the titration end point. Therefore, adopting this preset stirring speed can further improve the accuracy of the detection method for the ionic degree of cationic polyacrylamide. Optionally, the preset stirring speed can be 300rpm, 350rpm, 400rpm, 450rpm, 500rpm, 550rpm, 600rpm, etc. It can be understood that the preset stirring speed can also be other suitable selections within the range of 300rpm to 600rpm.

[0050] In some of these embodiments, when the PAMPSK standard titrant is dropped into the cationic polyacrylamide solution, the titration rate of the PAMPSK standard titrant can be 0.2 mL / min to 0.5 mL / min. At this time, it is possible to further ensure that the PAMPSK standard titrant can react fully with the cationic polyacrylamide solution quickly after being dropped, improving the accuracy of the titration volume of the PAMPSK standard titrant, and further improving the accuracy of the detection method for the ionic degree of cationic polyacrylamide. Optionally, the titration rate of the PAMPSK standard titrant can be 0.2 mL / min, 0.3 mL / min, 0.4 mL / min, 0.5 mL / min, etc. It can be understood that other suitable selections can also be made for the titration rate of the PAMPSK standard titrant within the range of 0.2 mL / min to 0.5 mL / min.

[0051] In some of these embodiments, the charge analyzer includes a controller, and the controller is used to control the stop of dropping the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant when the SCV value of the charge analyzer is 0.

[0052] In some of these embodiments, in step two, the sensor probe of the charge analyzer is placed in the cationic polyacrylamide solution. After the SCV value of the charge analyzer remains unchanged at a preset stirring speed, the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant is started to be dropped into the cationic polyacrylamide solution. At this time, the obtained SCV value can more accurately reflect the reaction situation in the solution, further improving the accuracy of the detection method for the ionic degree of cationic polyacrylamide. Optionally, after the SCV value of the charge analyzer remains unchanged for more than 5 s at a preset stirring speed, the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant is started to be dropped into the cationic polyacrylamide solution.

[0053] In some of these embodiments, preparing a cationic polyacrylamide solution with a preset concentration includes the following steps: weighing cationic polyacrylamide with a mass of m, adding a solvent to obtain a first solution with a volume of V. Pipetting a volume of V 1 of the first solution, adding a solvent to obtain a cationic polyacrylamide solution with a preset concentration, where V 1 < V.

[0054] In some of these embodiments, obtaining the titration volume of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution includes the following steps: recording the volume V of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution when the SCV value of the charge analyzer in step two is 0 2Obtain a solvent with a preset volume, which is equal to the volume of the cationic polyacrylamide solution, and the solvent is the solvent in the cationic polyacrylamide solution. Place the sensor probe of the charge analyzer into the solvent with the preset volume, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant into the solvent with the preset volume at a preset stirring speed until the SCV value of the charge analyzer is 0; record the volume V of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the solvent with the preset volume when the SCV value of the charge analyzer is 0 0 The titration volume is equal to V 2 -V 0 In these examples, the solvent in the cationic polyacrylamide solution is titrated with the PAMPSK standard titrant, and then based on V 2 and V 0 to determine the titration volume, which can eliminate the influence of the solvent in the cationic polyacrylamide solution on the detection result and is beneficial to further improving the accuracy of the detection method for the ionic degree of cationic polyacrylamide

[0055] Furthermore, calculating the ionic degree of cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume includes calculating the ionic degree according to formula (1):

[0056]

[0057] where n = (V 2 -V 0 )c×10 -3 . n represents the number of moles of acryloyloxyethyltrimethylammonium chloride cation monomer, with the unit of mol. The unit of m is g. w 1 represents the solid content of cationic polyacrylamide, with the unit of %. The unit of V 0 is mL. The unit of V 1 is mL. The unit of V 2 is mL. M 1 represents the molar mass of acryloyloxyethyltrimethylammonium chloride cation monomer, M 1 is 193.67 g / mol. M 2 represents the molar mass of acrylamide monomer, M 2 is 71.08 g / mol. c represents the molar concentration of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant, with the unit of mol / L; the unit of w is %. Optionally, the solid content of cationic polyacrylamide ≥ 88%. Further optionally, the solid content of cationic polyacrylamide ≥ 90%. Further optionally, the solid content of cationic polyacrylamide ≥ 92%. Further optionally, the solid content of cationic polyacrylamide ≥ 95%. Further optionally, the solid content of cationic polyacrylamide is 92% - 95%

[0058] In some of these embodiments, the solvent of the cationic polyacrylamide solution is water.

[0059] The technical solution of the present invention will be described in detail below in conjunction with specific embodiments.

[0060] Example 1

[0061] In this example, the ionic degree shown on the label of the cationic polyacrylamide sample is 12.58%.

[0062] The detection method for the ionic degree of cationic polyacrylamide in this example includes the following steps:

[0063] S101: Weigh cationic polyacrylamide with a mass of m, add solvent water to obtain a first solution with a volume of V; Pipette a volume of V 1 of the first solution, and add solvent water to obtain a cationic polyacrylamide solution with a preset concentration. Among them, m is 0.3 g. V is 500 mL. V 1 is 10 mL. The volume of the cationic polyacrylamide solution is 900 mL.

[0064] S102: Place the sensor probe of the charge analyzer into the cationic polyacrylamide solution, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant into the cationic polyacrylamide solution at a stirring speed of 400 rpm until the SCV value of the charge analyzer is 0. Record the volume V 2 of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the cationic polyacrylamide solution when the SCV value of the charge analyzer is 0.

[0065] S103: Place the sensor probe of the charge analyzer into 900 mL of water, and drop the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant into the water at a stirring speed of 400 rpm until the SCV value of the charge analyzer is 0. Record the volume V 0 of the potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant dropped into the water when the SCV value of the charge analyzer is 0.

[0066] S104: Calculate the titration volume. The titration volume is equal to V 2 -V 0 。

[0067] S105: Calculate the ionic degree of cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume. The calculation includes: calculating the ionic degree according to formula (1):

[0068]

[0069] Among them, n = (V 2 -V0 )c×10 -3 . n represents the number of moles of acryloyloxyethyltrimethylammonium chloride cationic monomer, with the unit of mol. The unit of m is g. w 1 represents the solid content of cationic polyacrylamide, with the unit of %. V 0 has the unit of mL. V 1 has the unit of mL. V 2 has the unit of mL. M 1 represents the molar mass of acryloyloxyethyltrimethylammonium chloride cationic monomer, M 1 is 193.67 g / mol. M 2 represents the molar mass of acrylamide monomer, M 2 is 71.08 g / mol. c represents the molar concentration of potassium poly(2-acrylamido-2-methylpropanesulfonate) standard titrant, with the unit of mol / L.

[0070] The ionic degree of the cationic polyacrylamide in this example is calculated to be 12.58%.

[0071] Example 2

[0072] The method in Example 1 was used to repeat the test on the ionic degree of the same cationic polyacrylamide sample. The number of repetitions was 9 times.

[0073] The results of the ionic degree of the cationic polyacrylamide obtained in Example 1 and Example 2 are shown in Table 1. It can be understood that in Table 1, serial number 1 represents Example 1, and serial numbers 2 - 9 represent the repeated experiments in Example 2.

[0074] Table 1

[0075] Serial number 1 2 3 4 5 6 7 8 9 10 Degree of ionization 12.58％ 12.56％ 12.58％ 12.57％ 12.59％ 12.56％ 12.58％ 12.57％ 12.56％ 12.57％

[0076] Comparative Example 1

[0077] For the cationic polyacrylamide sample in Example 1, the ionic degree was tested by the method of manual titration and human eye recognition of the titration end point by the same operator, and the test was repeated 10 times. The test results are shown in Table 2.

[0078] Table 2

[0079] Serial number 1 2 3 4 5 6 7 8 9 10 Degree of ionization 11.24％ 12.47％ 10.63％ 13.22％ 12.77％ 11.68％ 12.96％ 13.87％ 14.01％ 12.81％

[0080] It can be seen from Table 1 and Table 2 that the ionic degree results in Table 1 are closer to the actual ionic degree of the sample, indicating that the test method in the example has higher accuracy. At the same time, the results in Table 1 have better repeatability compared with the results in Table 2, indicating that the test method in the example has better repeatability.

[0081] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0082] For those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for detecting the ionicity of cationic polyacrylamide, characterized in that: The steps include: Step 1: preparing a cationic polyacrylamide solution with a preset concentration; Step 2: placing a sensor probe of the charge analyzer in the cationic polyacrylamide solution, and dripping a standard titration solution of potassium poly(2-acrylamide-2-methylpropanesulfonate) into the cationic polyacrylamide solution at a preset stirring speed until the SCV value of the charge analyzer is 0; Step 3: obtaining the titration volume of the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution dripped into the cationic polyacrylamide solution; Step 4: Calculate the ionicity of the cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume.

2. The method for detecting the ionicity of cationic polyacrylamide according to claim 1, wherein: The preset concentration is 4 mg / L to 10 mg / L.

3. The method for detecting the ionicity of cationic polyacrylamide as claimed in claim 1, characterized in that: The preset stirring speed is 300 rpm to 600 rpm.

4. The method for detecting the ionicity of cationic polyacrylamide according to claim 1, wherein: The charge analyzer comprises a controller, and the controller is used for controlling to stop dripping the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution when the SCV value of the charge analyzer is 0.

5. The method for detecting the ionicity of cationic polyacrylamide according to claim 1, characterized in that: In step 2, the sensor probe of the charge analyzer is placed in the cationic polyacrylamide solution. After the SCV value of the charge analyzer remains unchanged at the preset stirring speed, the poly (2-acrylamide-2-methylpropanesulfonic acid potassium) standard titration solution is dripped into the cationic polyacrylamide solution.

6. The method for detecting the ionicity of cationic polyacrylamide as claimed in claim 5, characterized in that: After the SCV value of the charge analyzer remains constant for more than 5 seconds at the preset stirring speed, the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution begins to be dripped into the cationic polyacrylamide solution.

7. The method for detecting the ionicity of cationic polyacrylamide according to any one of claims 1 to 6, characterized in that: The steps of preparing the cationic polyacrylamide solution having the preset concentration include: Weighing cationic polyacrylamide with a mass of m, adding a solvent to obtain a first solution with a volume of V; The first solution with a volume of V1 is transferred, and a solvent is added to obtain the cationic polyacrylamide solution with the preset concentration, V1<V.

8. The method for detecting the ionicity of cationic polyacrylamide according to claim 7, characterized in that: Obtaining the titration volume of the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution dripped into the cationic polyacrylamide solution comprises the following steps: Record the volume V2 of the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution dripped into the cationic polyacrylamide solution when the SCV value of the charge analyzer in step 2 is 0; Obtaining a preset volume of solvent, wherein the preset volume is equal to the volume of the cationic polyacrylamide solution, and the solvent is the solvent in the cationic polyacrylamide solution; Placing the sensor probe of the charge analyzer in the preset volume of solvent, dripping the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution into the preset volume of solvent at the preset stirring speed until the SCV value of the charge analyzer is 0; recording the volume V0 of the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution dripped into the preset volume of solvent when the SCV value of the charge analyzer is 0; The titration volume is equal to V2-V0.

9. The method for detecting the ionicity of cationic polyacrylamide as claimed in claim 8, characterized in that: Calculating the ionicity of the cationic polyacrylamide in the cationic polyacrylamide solution according to the titration volume includes: calculating the ionicity according to formula (1): Where n = (V2-V0)c×10 -3 ; n represents the mole number of acryloyloxyethyltrimethylammonium chloride cationic monomer, in mol; The unit of m is g; w1 represents the solid content of the cationic polyacrylamide, in %; The unit of V0 is mL; The unit of V1 is mL; The unit of V2 is mL; M1 represents the molar mass of acryloyloxyethyltrimethylammonium chloride cationic monomer, M1 is 193.67 g / mol; M2 represents the molar mass of acrylamide monomer, M2 is 71.08 g / mol; c represents the molar concentration of the poly (2-acrylamide-2-methylpropanesulfonate potassium) standard titration solution, in mol / L; The unit of w is %.

10. The method for detecting the ionicity of cationic polyacrylamide according to any one of claims 1 to 6, characterized in that: The solvent of the cationic polyacrylamide solution is water.

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