Method for monitoring photocatalytic degradation of polyacrylamide

Abstract

The invention belongs to the technical field of photocatalytic degradation, and particularly provides a polyacrylamide photocatalytic degradation monitoring method which comprises the following steps: preparing a homogeneous polyacrylamide gel solution; carrying out photocatalytic degradation on the homogeneous polyacrylamide gel solution; measuring the polyacrylamide gel solution at different time during photocatalytic degradation through liquid chromatography; and monitoring the photocatalytic degradation degree of the polyacrylamide gel in real time according to a result measured by the liquid chromatography to finish the detection. The problem that the polyacrylamide degradation degree cannot be monitored in real time during existing polyacrylamide degradation is solved, the polyacrylamide gel photocatalytic degradation proceeding degree can be monitored in real time, the speed is high, operation is easy and convenient, interference factors are few, accuracy is high, repeatability is good, and the degradation process and the change condition of degradation products can be monitored at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalytic degradation, and in particular relates to a monitoring method for photocatalytic degradation of polyacrylamide. Background Art

[0002] Polyacrylamide has the functions of thickening, flocculation, drag reduction, purification, etc., and is called "agent for all industries". Polyacrylamide contains a high molecular carbon chain and has biological resistance. It has long been considered stable and safe. However, scientific research now shows that sewage containing polyacrylamide has a high viscosity and its discharge will cause harm to the environment. Through migration, stratum adsorption and other processes, polyacrylamide can cause long-term harm to soil and water bodies. In addition, polyacrylamide can also spontaneously degrade into acrylamide, and monomer acrylamide is toxic and harmful to human nerves. Direct contact will cause symptoms such as eye inflammation, dizziness, and headache. It will also affect lung function, and long-term contact may cause cancer and have adverse effects on human health. Therefore, it is of great practical significance to study effective methods for degrading polyacrylamide. At present, there are physical degradation, chemical degradation and biological degradation methods for the degradation of polyacrylamide. Among them, the photocatalytic degradation in the chemical degradation method has attracted widespread attention due to its mild conditions, complete degradation of polyacrylamide at room temperature and pressure, no secondary pollution, and low cost. In the research process of polyacrylamide photocatalytic degradation, real-time monitoring of the degree of polyacrylamide photocatalytic degradation is an indispensable and important part of evaluating the performance of photocatalysts and the study of photocatalytic mechanism.

[0003] The methods currently used to monitor the degree of polymer degradation are viscosity method, starch-cadmium iodide colorimetry, near-infrared spectroscopy, and ultraviolet spectrophotometry. Although the viscosity method is simple, its accuracy and reproducibility are poor, and as the degradation proceeds, when the viscosity of the polyacrylamide solution is reduced to a certain extent, the viscosity method will no longer be able to reflect the further degradation of polyacrylamide. Starch-cadmium iodide colorimetry (CN 1139808C) is a classic method for detecting the concentration of polyacrylamide, but its operation process is cumbersome, time-consuming, and has many interfering factors, which seriously affects the accuracy and repeatability of the measurement results. Near-infrared spectroscopy (CN102262055B), ultraviolet spectrophotometry (CN 102914511B) and the above two methods are only for monitoring the content of undegraded polyacrylamide, and cannot reflect the changes in the degradation process and degradation products.

[0004] A Chinese patent document with publication number CN104043463A and publication date September 17, 2014 discloses a method for preparing a photocatalyst for degrading polyacrylamide that is responsive to visible light and its application. The method for preparing a photocatalyst for degrading polyacrylamide that is responsive to visible light disclosed in the document first uses an improved Hummers method to prepare graphene oxide, then uses a hydrothermal method to prepare graphene, and then uses graphene, titanium dioxide, a bromine source, a silver salt and ammonia water as raw materials to prepare a photocatalyst that is responsive to visible light through a deposition-precipitation and photoreduction method and high-temperature calcination, and uses this catalyst to degrade polyacrylamide polymers in an aqueous solution. However, the document cannot monitor the content of polyacrylamide during degradation, and cannot reflect the degradation process and changes in degradation products. Summary of the invention

[0005] The present invention provides a method for monitoring the photocatalytic degradation of polyacrylamide, aiming to overcome the problem in the prior art that the degradation degree of polyacrylamide cannot be monitored in real time when the polyacrylamide is degraded.

[0006] To this end, the present invention provides a method for monitoring the photocatalytic degradation of polyacrylamide, comprising the following steps:

[0007] 1) preparing a homogeneous polyacrylamide gel solution;

[0008] 2) Photocatalytic degradation of homogeneous polyacrylamide gel solution;

[0009] 3) measuring the polyacrylamide gel solution at different times during photocatalytic degradation by liquid chromatography;

[0010] 4) According to the results measured by liquid chromatography, the degree of photocatalytic degradation of polyacrylamide gel is monitored in real time to complete the detection.

[0011] Preferably, the method for preparing a homogeneous polyacrylamide gel solution in step 1) comprises the following steps: taking 150 mL of distilled water into a container, adjusting the container rotation speed to 1500±250 rpm, adding 15-30 mg of polyacrylamide gel powder to the distilled water in the container, and continuously stirring until the polyacrylamide gel powder is completely expanded, breaking the expanded polyacrylamide gel solution into a homogeneous polyacrylamide gel solution to complete the preparation.

[0012] Preferably, in step 1), when 15 to 30 mg of polyacrylamide gel powder is added to the distilled water in the container, the polyacrylamide gel powder needs to be evenly sprayed in the middle of the vortex of the distilled water within 30 seconds.

[0013] Preferably, the concentration of the homogeneous polyacrylamide gel solution is 100 mg / L to 200 mg / L.

[0014] Preferably, the step 2) photocatalytically degrading the homogeneous polyacrylamide gel solution comprises the following steps: adding 0.1 g of P25 photocatalyst to 100 mL of homogeneous polyacrylamide gel solution, and photocatalytically degrading the solution after ultrasonic dispersion using a high-pressure mercury lamp with a power of 100 W.

[0015] Preferably, the condition 1 during the liquid chromatography determination in step 3) is: chromatographic column: polymer chromatographic column; mobile phase: 250mmol / L NaH2PO4 aqueous solution; flow rate: 1.0mL / min; detector: UV detector 200nm; injection volume: 20μL; column temperature: 25°C.

[0016] Preferably, the second condition in the step 3) liquid chromatography determination is: chromatographic column: C18 chromatographic column; mobile phase: water / acetonitrile = 90 / 10 (v / v); flow rate: 1.0 mL / min; detector: UV detector 200 nm; injection volume: 20 μL; column temperature: 25°C.

[0017] Preferably, the C18 chromatographic column model is Agilent ZORBAX Extend-C18, with a length of 250 mm, an inner diameter of 4.6 mm, a chromatographic column filler particle diameter of 5 μm, and a pore size of

[0018] Preferably, in step 1), a homogenizer is used to break the swollen polyacrylamide gel solution into a homogeneous polyacrylamide gel solution.

[0019] Preferably, the homogenizer continuously breaks up the swollen polyacrylamide gel solution at a speed of 20,000 rpm for 90 to 100 minutes to break up the polyacrylamide gel solution into a homogeneous polyacrylamide gel solution.

[0020] Beneficial effects of the present invention:

[0021] 1. The monitoring method of the photocatalytic degradation of polyacrylamide provided by the present invention comprises the following steps: first preparing a homogeneous polyacrylamide gel solution; then photocatalytically degrading the homogeneous polyacrylamide gel solution; then measuring the polyacrylamide gel solution at different times during the photocatalytic degradation by liquid chromatography; finally, according to the results measured by liquid chromatography (after separation by a chromatographic column, the changes in the chromatogram obtained can reflect the real-time changes of the polymer and the degradation product), real-time monitoring of the degree of photocatalytic degradation of the polyacrylamide gel is completed. The method can monitor the degree of photocatalytic degradation of the polyacrylamide gel in real time, has a fast speed, is easy to operate, has few interference factors, is highly accurate, has good repeatability, and can simultaneously monitor the changes in the degradation process and the degradation products.

[0022] 2. In the monitoring method for photocatalytic degradation of polyacrylamide provided by the present invention, when 15 to 30 mg of polyacrylamide gel powder is added to the distilled water in the container, the polyacrylamide gel powder needs to be evenly sprayed in the middle of the vortex of the distilled water within 30 seconds to avoid the formation of "fish eyes".

[0023] 3. The monitoring method for photocatalytic degradation of polyacrylamide provided by the present invention monitors polyacrylamide in real time by setting two chromatographic analysis conditions, thereby completing real-time monitoring more accurately and comprehensively. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described in detail below with reference to the accompanying drawings.

[0025] Figure 1 is a liquid chromatogram of 1# polyacrylamide gel solution with different photocatalytic degradation times on a polymer chromatography column in the embodiment;

[0026] Figure 2 is a liquid chromatogram of 1# polyacrylamide gel solution with different photocatalytic degradation times on a C18 chromatographic column in the embodiment;

[0027] Figure 3 is a liquid chromatogram of 2# polyacrylamide gel solution with different photocatalytic degradation times on a polymer chromatography column in the embodiment;

[0028] Figure 4 It is the liquid chromatogram of 2# polyacrylamide gel solution with different photocatalytic degradation time on C18 chromatographic column in the embodiment. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. If specific conditions are not specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0030] A method for monitoring photocatalytic degradation of polyacrylamide comprises the following steps:

[0031] 1) preparing a homogeneous polyacrylamide gel solution;

[0032] Preferably, the method for preparing a homogeneous polyacrylamide gel solution in step 1) comprises the following steps: taking 150 mL of distilled water into a container, adjusting the container rotation speed to 1500±250 rpm, adding 15-30 mg of polyacrylamide gel powder to the distilled water in the container, and continuously stirring until the polyacrylamide gel powder is completely expanded, breaking the expanded polyacrylamide gel solution into a homogeneous polyacrylamide gel solution to complete the preparation.

[0033] Preferably, in step 1), a homogenizer is used to break the swollen polyacrylamide gel solution into a homogeneous polyacrylamide gel solution.

[0034] Preferably, the homogenizer continuously breaks up the swollen polyacrylamide gel solution at a speed of 20,000 rpm for 90 to 100 minutes to break up the polyacrylamide gel solution into a homogeneous polyacrylamide gel solution.

[0035] Preferably, in step 1), when 15 to 30 mg of polyacrylamide gel powder is added to the distilled water in the container, the polyacrylamide gel powder needs to be evenly sprayed in the middle of the vortex of the distilled water within 30 seconds.

[0036] Preferably, the concentration of the homogeneous polyacrylamide gel solution is 100 mg / L to 200 mg / L.

[0037] Specifically, 150 mL of distilled water is measured with a measuring cylinder into a 250 mL container; the container is placed on the stirrer, a magnetic stirring bar is placed in the container, and the container is adjusted in the stirrer position, and the rotation speed is adjusted to 1500 ± 250 rpm; 15 to 30 mg of polyacrylamide gel powder is weighed into a weighing dish; all the polyacrylamide gel powder in the weighing dish is added into the container, and the polyacrylamide gel powder should be evenly sprayed in the middle of the vortex within 30 seconds to avoid the formation of "fish eyes"; continuous stirring for 24 to 36 hours to fully expand the polyacrylamide gel particles, and the heterogeneous polyacrylamide gel solution is broken up with an Aika homogenizer at 20,000 rpm for 90 to 100 minutes to obtain a homogeneous polyacrylamide gel solution.

[0038] 2) Photocatalytic degradation of homogeneous polyacrylamide gel solution;

[0039] Preferably, the step 2) photocatalytically degrading the homogeneous polyacrylamide gel solution comprises the following steps: adding 0.1 g of P25 photocatalyst to 100 mL of homogeneous polyacrylamide gel solution, and photocatalytically degrading the solution after ultrasonic dispersion using a high-pressure mercury lamp with a power of 100 W.

[0040] Specifically, 0.1 g of P25 photocatalyst was added to a conical flask containing 100 mL of homogeneous polyacrylamide gel solution, and ultrasonically dispersed uniformly, and the conical flask was placed in a sheet metal dark box equipped with a high-pressure mercury lamp (power 100 W) for photocatalytic degradation. P25 is titanium dioxide in a mixed phase of anatase crystal and rutile crystal with an average particle size of 25 nanometers.

[0041] 3) measuring the polyacrylamide gel solution at different times during photocatalytic degradation by liquid chromatography;

[0042] Specifically, 0.5 mL of the polyacrylamide gel solution was taken out at regular intervals for liquid chromatography testing.

[0043] Preferably, the condition 1 during the liquid chromatography determination in step 3) is: chromatographic column: polymer chromatographic column; mobile phase: 250mmol / L NaH2PO4 aqueous solution; flow rate: 1.0mL / min; detector: UV detector 200nm; injection volume: 20μL; column temperature: 25°C.

[0044] Under the conditions of liquid chromatography measurement, chromatograms of homogeneous polyacrylamide gel solutions with different photocatalytic degradation times were obtained. It can be found that with the increase of photocatalytic time, the chromatographic peak at 1.1 min gradually decreased until it disappeared, indicating that the ultra-large molecular polymer has been completely degraded into compounds of different small molecular weights. At the same time, the chromatographic peak of the photocatalytic degradation product gradually became narrower and higher until it no longer changed, indicating that the molecular weight of the degradation product became smaller and smaller, and more and more concentrated, until the polymer was completely degraded.

[0045] Preferably, the second condition in the step 3) liquid chromatography determination is: chromatographic column: C18 chromatographic column; mobile phase: water / acetonitrile = 90 / 10 (v / v); flow rate: 1.0 mL / min; detector: UV detector 200 nm; injection volume: 20 μL; column temperature: 25°C.

[0046] Preferably, the C18 chromatographic column model is Agilent ZORBAX Extend-C18, with a length of 250 mm, an inner diameter of 4.6 mm, a chromatographic column filler particle diameter of 5 μm, and a pore size of

[0047] Under the condition 2 of liquid chromatography determination, the chromatograms of homogeneous polyacrylamide gel solutions with different photocatalytic degradation times were obtained. It can be found that with the increase of photocatalytic time, the chromatographic peaks before 3.6min became more and more single, narrower and higher, indicating that the chromatographic peaks in this area are small molecular products of photocatalytic degradation. As the photocatalytic degradation progresses, the degradation products become more and more concentrated and the content increases. At the same time, the chromatographic peak at 3.6min shows a trend of increasing first and then decreasing, indicating that the linear part of the polymer is first decomposed into relatively short chains at the beginning of photocatalytic degradation. In the later stage of photocatalytic degradation, the shorter chains continue to degrade into small molecules. The chromatographic peak at 3.6min should be the chromatographic peak of the transition product of the linear part of the polymer. In the early stage of catalytic degradation, the chromatographic peak at 34min has basically no obvious changes. In the later stage of photocatalytic degradation, as the photolysis time increases, the chromatographic peak gradually decreases, indicating that the cross-linked part of the polymer is not easy to be degraded. Only when the photocatalytic degradation reaches a certain time can it be decomposed into molecules with smaller molecular weight. When the chromatogram no longer changes, it means that the photocatalytic degradation of polyacrylamide gel is completed.

[0048] 4) According to the results measured by liquid chromatography, the degree of photocatalytic degradation of polyacrylamide gel is monitored in real time to complete the detection.

[0049] The present invention realizes real-time monitoring of the degradation degree of polyacrylamide. The monitoring method is not only fast, simple to operate, has few interference factors, high accuracy and good repeatability, but also can simultaneously monitor the degradation process and the changes of the degradation products.

[0050] Embodiment 1:

[0051] A method for monitoring photocatalytic degradation of polyacrylamide comprises the following steps:

[0052] 1) preparing a homogeneous polyacrylamide gel solution;

[0053] The method for preparing a homogeneous polyacrylamide gel solution comprises the following steps: measuring 150 mL of distilled water into a 250 mL container; placing the container on a stirrer, placing a magnetic stirring bar in the container, adjusting the container in the stirrer position, and adjusting the rotation speed to 1500±250 rpm; weighing 15 mg of 1# polyacrylamide gel powder and adding it into the container, and the polyacrylamide gel powder should be evenly sprayed in the middle of the vortex within 30 seconds to avoid forming "fish eyes"; stirring continuously for 24 hours to fully expand the polyacrylamide gel particles, and breaking the heterogeneous polyacrylamide gel solution with an Aika homogenizer at 20,000 rpm for 90 minutes to obtain a homogeneous 1# polyacrylamide gel solution with a concentration of 100 mg / L.

[0054] 2) Photocatalytic degradation of homogeneous polyacrylamide gel solution;

[0055] The photocatalytic degradation of the homogeneous polyacrylamide gel solution includes the following steps: adding 0.1 g of P25 photocatalyst to 100 mL of homogeneous 1# polyacrylamide gel solution, placing the solution after ultrasonic dispersion in a sheet metal dark box equipped with a high-pressure mercury lamp (power 100 W) for photocatalytic degradation.

[0056] 3) measuring the polyacrylamide gel solution at different times during photocatalytic degradation by liquid chromatography;

[0057] At regular intervals, 0.5 mL of the polyacrylamide gel solution was taken out for liquid chromatography testing.

[0058] The conditions for liquid chromatography determination were: Agilent 1100 liquid chromatograph, polymer column (4.6 mm × 150 mm, 5 μm, ); mobile phase: 250 mM NaH2PO4 solution; flow rate: 1.0 mL / min; detector: UV detector 200 nm; injection volume: 20 μL; column temperature: 25°C.

[0059] The second condition for liquid chromatography determination was: Agilent 1100 liquid chromatograph, Agilent ZORBAXExtend-C18 (4.6 mm × 250 mm, 5 μm, ); mobile phase: water / acetonitrile = 10 / 90 (v / v); flow rate: 1.0 mL / min; detector: UV detector 200 nm; injection volume: 20 μL; column temperature: 25°C.

[0060] According to the above-mentioned liquid chromatography determination condition 1, 1# polyacrylamide gel solutions with different photocatalytic degradation times were injected respectively. Figure 1 This is the liquid chromatogram of 1# polyacrylamide gel solution with different photocatalytic degradation times on the polymer chromatography column.

[0061] According to the second condition of the above-mentioned liquid chromatography determination, 1# polyacrylamide gel solutions with different photocatalytic degradation times were injected respectively. Figure 2 This is the liquid chromatogram of 1# polyacrylamide gel solution with different photocatalytic degradation times on a C18 chromatographic column.

[0062] 4) Based on the results measured by liquid chromatography, the degree of photocatalytic degradation of polyacrylamide gel is monitored in real time.

[0063] from Figure 1It can be seen that after 1 hour of photocatalytic degradation, the chromatographic peak at 1.1 minutes disappears, and the subsequent chromatographic peaks become wider, indicating that the ultra-large molecular polymer has been completely degraded into compounds of different small molecular weights. As the degradation time increases, the chromatographic peaks become narrower and narrower, indicating that the molecular weight of the degradation products is getting smaller and more concentrated. After 12 hours of photocatalytic degradation, the chromatographic peaks remain basically unchanged, indicating that the polymer has been completely degraded into small molecules.

[0064] from Figure 2 It can be seen that with the extension of photocatalytic degradation time, the chromatographic peak before 3.6min becomes more and more single, and the chromatographic peak becomes narrower and higher, indicating that the chromatographic peak in this area is the small molecule product of photocatalytic degradation. With the progress of photocatalytic degradation, the photocatalytic degradation products become more and more concentrated, and the content becomes more and more. At the same time, the chromatographic peak at 3.6min shows a trend of first increasing and then decreasing, indicating that at the beginning of photocatalytic degradation, the linear part of the polymer is first decomposed into relatively short chains. In the later stage of photocatalytic degradation, the shorter chains continue to decompose into small molecules. The chromatographic peak at 3.6min should be the chromatographic peak of the transition product of the linear part of the polymer. In the early stage of photocatalytic degradation, the chromatographic peak at 34min has basically no obvious change. In the later stage of photocatalytic degradation, with the extension of photolysis time, the chromatographic peak gradually decreases, indicating that the cross-linked part of the polymer is not easy to be photocatalytically degraded. Only when the photocatalytic degradation reaches a certain time can it be decomposed into molecules with smaller molecular weight, which gradually appear at 4.2, 4.5, and 8.0min on the chromatogram.

[0065] Embodiment 2:

[0066] A method for monitoring photocatalytic degradation of polyacrylamide comprises the following steps:

[0067] 1) preparing a homogeneous polyacrylamide gel solution;

[0068] The method for preparing a homogeneous polyacrylamide gel solution comprises the following steps: measuring 150 mL of distilled water into a 250 mL container; placing the container on a stirrer, placing a magnetic stirring rod in the container, adjusting the container in the stirrer position, and adjusting the rotation speed to 1500±250 rpm; weighing 30 mg of 2# polyacrylamide gel powder and adding it into the container, and the polyacrylamide gel powder should be evenly sprayed in the middle of the vortex within 30 seconds to avoid forming "fish eyes"; stirring continuously for 36 hours to fully expand the polyacrylamide gel particles, and breaking the heterogeneous polyacrylamide gel solution with an Aika homogenizer at 20,000 rpm for 100 minutes to obtain a homogeneous 2# polyacrylamide gel solution with a concentration of 200 mg / L.

[0069] 2) Photocatalytic degradation of homogeneous polyacrylamide gel solution;

[0070] The photocatalytic degradation of the homogeneous polyacrylamide gel solution includes the following steps: adding 0.1 g of P25 photocatalyst to 100 mL of homogeneous 2# polyacrylamide gel solution, placing the solution after ultrasonic dispersion in a sheet metal dark box equipped with a high-pressure mercury lamp (power 100 W) for photocatalytic degradation.

[0071] 3) measuring the polyacrylamide gel solution at different times during photocatalytic degradation by liquid chromatography;

[0072] At regular intervals, 0.5 mL of the polyacrylamide gel solution was taken out for liquid chromatography testing.

[0073] The conditions for liquid chromatography determination were: Agilent 1100 liquid chromatograph, polymer column (4.6 mm × 150 mm, 5 μm, ); mobile phase: 250 mM NaH2PO4 solution; flow rate: 1.0 mL / min; detector: UV detector 200 nm; injection volume: 20 μL; column temperature: 25°C.

[0074] The second condition for liquid chromatography determination was: Agilent 1100 liquid chromatograph, Agilent ZORBAXExtend-C18 (4.6 mm × 250 mm, 5 μm, ); mobile phase: water / acetonitrile = 10 / 90 (v / v); flow rate: 1.0 mL / min; detector: UV detector 200 nm; injection volume: 20 μL; column temperature: 25°C.

[0075] According to the above-mentioned liquid chromatography determination condition 1, 2# polyacrylamide gel solutions with different photocatalytic degradation times were injected respectively. Figure 3 The liquid chromatogram of 2# polyacrylamide gel solution with different photocatalytic degradation times on the polymer chromatography column.

[0076] According to the second condition of the above-mentioned liquid chromatography determination, 2# polyacrylamide gel solutions with different photocatalytic degradation times were injected respectively. Figure 4 The liquid chromatogram of 2# polyacrylamide gel solution with different photocatalytic degradation times on C18 chromatographic column.

[0077] 4) Based on the results measured by liquid chromatography, the degree of photocatalytic degradation of polyacrylamide gel is monitored in real time.

[0078] from Figure 3It can be seen that after 3 hours of photocatalytic degradation, the chromatographic peak at 1.1 minutes disappears, and the subsequent chromatographic peaks become wider, indicating that the ultra-large molecular polymer has been completely degraded into compounds of different small molecular weights. As the degradation time increases, the chromatographic peak becomes narrower and narrower, indicating that the molecular weight of the degradation product is getting smaller and more concentrated. After 10 hours of photocatalytic degradation, the chromatographic peak remains basically unchanged, indicating that the polymer has been completely degraded into small molecules.

[0079] from Figure 4 It can be seen that with the extension of photocatalytic degradation time, the chromatographic peak before 3.6min becomes more and more single, narrower and higher, indicating that the chromatographic peak in this area is the small molecule product of photocatalytic degradation. With the progress of photolysis, the photolysis products become more and more concentrated and the content increases. At the same time, the chromatographic peak at 3.6min shows a trend of first increasing and then decreasing, indicating that at the beginning of photocatalytic degradation, the linear part of the polymer first decomposes into relatively short chains. In the later stage of photocatalytic degradation, the shorter chains continue to decompose into small molecules. The chromatographic peak at 3.6min should be It is the chromatographic peak of the transition product of the linear part of the polymer; in the early stage of photocatalytic degradation, the chromatographic peak at 34min basically has no obvious change. In the later stage of photocatalytic degradation, as the photocatalytic degradation time increases, the chromatographic peak gradually decreases, indicating that the cross-linked part of the polymer is not easy to be photocatalytically degraded. It can only be degraded after the photocatalytic degradation reaches a certain time. In addition, due to the high cross-linking strength, photocatalytic degradation can only be carried out from the outside to the inside. Since the carbon chain outside the cross-linking point is short, during photocatalytic degradation, HO· directly attacks the peripheral short carbon chain to generate small molecular products, so no intermediate products can be seen on the chromatogram.

[0080] The above examples are merely illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. All designs that are the same or similar to the present invention fall within the protection scope of the present invention.

Claims

1. A method for monitoring photocatalytic degradation of polyacrylamide, characterized in that: The steps include: 1) preparing a homogeneous polyacrylamide gel solution; 2) Photocatalytic degradation of homogeneous polyacrylamide gel solution; 3) measuring the polyacrylamide gel solution at different times during photocatalytic degradation by liquid chromatography; 4) According to the results measured by liquid chromatography, the degree of photocatalytic degradation of polyacrylamide gel is monitored in real time to complete the detection.

2. The method for monitoring the photocatalytic degradation of polyacrylamide according to claim 1, characterized in that: The method for preparing a homogeneous polyacrylamide gel solution in step 1) comprises the following steps: taking 150 mL of distilled water into a container, adjusting the rotation speed of the container to 1500±250 rpm, adding 15 to 30 mg of polyacrylamide gel powder to the distilled water in the container, and continuously stirring until the polyacrylamide gel powder is completely expanded, breaking the expanded polyacrylamide gel solution into a homogeneous polyacrylamide gel solution, and completing the preparation.

3. The method for monitoring the photocatalytic degradation of polyacrylamide according to claim 2, characterized in that: In the step 1), when 15 to 30 mg of polyacrylamide gel powder is added to the distilled water in the container, the polyacrylamide gel powder needs to be evenly sprayed in the middle of the vortex of the distilled water within 30 seconds.

4. The method for monitoring the photocatalytic degradation of polyacrylamide according to claim 1, characterized in that: The concentration of the homogeneous polyacrylamide gel solution is 100 mg / L to 200 mg / L.

5. The method for monitoring photocatalytic degradation of polyacrylamide according to claim 1, characterized in that: The step 2) photocatalytically degrading the homogeneous polyacrylamide gel solution comprises the following steps: adding 0.1 g of P25 photocatalyst to 100 mL of homogeneous polyacrylamide gel solution, and photocatalytically degrading the solution after ultrasonic dispersion using a high-pressure mercury lamp with a power of 100 W.

6. The method for monitoring the photocatalytic degradation of polyacrylamide according to claim 1, characterized in that: The conditions for the liquid chromatography determination in step 3) are: chromatographic column: polymer chromatographic column; mobile phase: 250 mmol / L NaH2PO4 aqueous solution; flow rate: 1.0 mL / min; Detector: UV detector 200nm; injection volume: 20μL; Column temperature: 25℃.

7. The method for monitoring photocatalytic degradation of polyacrylamide according to claim 1, characterized in that: The second condition for the liquid chromatography determination in step 3) is: chromatographic column: C18 chromatographic column; mobile phase: water / acetonitrile = 90 / 10 (v / v); flow rate: 1.0 mL / min; Detector: UV detector 200nm; injection volume: 20μL; column temperature: 25℃.

8. The method for monitoring photocatalytic degradation of polyacrylamide according to claim 1, characterized in that: The C18 chromatographic column model is Agilent ZORBAX Extend-C18, with a length of 250 mm, an inner diameter of 4.6 mm, a chromatographic column filler particle diameter of 5 μm, and a pore size of 9. The method for monitoring the photocatalytic degradation of polyacrylamide according to claim 2, characterized in that: In the step 1), a homogenizer is used to break the swollen polyacrylamide gel solution into a homogeneous polyacrylamide gel solution.

10. The method for monitoring photocatalytic degradation of polyacrylamide according to claim 9, characterized in that: The homogenizer continuously breaks the swollen polyacrylamide gel solution at a speed of 20,000 rpm for 90 to 100 minutes to break the polyacrylamide gel solution into a homogeneous polyacrylamide gel solution.

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