CN118329878A - Preparation method of Dragendorff optimizing reagent and ultrafiltration membrane rejection rate testing method - Google Patents
Preparation method of Dragendorff optimizing reagent and ultrafiltration membrane rejection rate testing method Download PDFInfo
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Abstract
The invention relates to a preparation method of Dragendorff optimizing reagent and an ultrafiltration membrane rejection rate testing method; comprises preparing bismuth subnitrate solution with concentration of 80 g/L; respectively weighing potassium iodide, iodine and water, mixing, transferring into a brown volumetric flask, and shaking uniformly to obtain iodine-containing mixed solution, wherein the mass ratio of the potassium iodide to the iodine to the water is 4:1:5; bismuth subnitrate solution, iodine-containing mixed solution, anhydrous acetic acid and water are mixed according to the volume ratio of 0.5:10:20:69.5 and uniformly shaken to obtain the Dragendorff optimized reagent, and the problem that the reagent D is easy to oxidize and poor in stability is effectively solved due to the addition of potassium iodide and iodine, so that the accuracy of a test result is ensured, the stability of a color developing agent is improved, and the storage time is prolonged.
Description
Technical Field
The invention relates to the technical field of preparation methods of Dragendorff optimized reagents, in particular to a preparation method of Dragendorff optimized reagents and an ultrafiltration membrane rejection rate test method.
Background
Along with the rapid development of ultrafiltration membrane technology, accurate membrane evaluation and determination methods are helpful for understanding the influencing factors, change rules and quality control of the membrane in the preparation process. The molecular weight cut-off is an important basis for distinguishing and selecting ultrafiltration membranes according to different separation requirements in different industries, so that the ultrafiltration membranes have vector discharge. In the test process, firstly, a standard substance (marker) with relative molecular mass is selected to be prepared into an aqueous solution with proper concentration, then the aqueous solution is filtered by a membrane, the concentration of the marker solution before and after filtration is measured, and the rejection rate of the membrane is determined by comparison. Spectrophotometry for determining markers is currently the mainstream method, and the principle is mainly based on lambert-beer law, and the concentration of solutions is determined by utilizing the difference of light absorption capacities of solutions with different concentrations. The protein is a high molecular substance formed by connecting polyamino acid through peptide bonds, is widely applied to the aperture of the characterization ultrafiltration membrane, but under different pH values, the charge of the protein can change and influence the measurement result of the retention rate, and meanwhile, the molecular weight application range of the protein is small, the adsorptivity of the membrane material is relatively large, the membrane pollution is easy to cause, and the test accuracy is influenced. In addition, proteins tend to be relatively expensive. The polyethylene glycol has complete specification and low reagent price, and is a relatively convenient and popularized method.
When the domestic laboratory detects the rejection rate of the ultrafiltration membrane, the national ocean office industry standard HY/T050-1999 hollow fiber ultrafiltration membrane test method is usually implemented. The method provides for detecting the concentration of polyethylene glycol by using a D reagent method, namely, polyethylene glycol solutions with different concentrations are prepared to respectively react with the D reagent in a color development way, the absorbance of a series of polyethylene glycol standard solutions under the wavelength of 510nm is measured by using a spectrophotometer, and a standard curve is drawn for quantitative analysis. Patent CN106124387A discloses a method for testing the rejection rate of an ultrafiltration membrane, which uses star-shaped polyethylene glycol as a reference substance, takes raw material liquid and filtrate to be subjected to color development treatment by a color development reagent D reagent and an acetic acid-sodium acetate buffer solution for 15min at room temperature, then determines absorbance at a wavelength of 510nm, calculates the concentration of the star-shaped polyethylene glycol, and calculates the rejection rate R (%) according to a formula. However, in the prior art, the interception rate of polyethylene glycol by a film product is mainly determined by a spectrophotometry, when the concentration of polyethylene glycol is determined by a conventional D reagent method, the D reagent is not resistant to visible light, is easy to oxidize and store, and the measurement result is inaccurate and the experimental repeatability is poor.
Therefore, in order to solve the above problems, the present invention is needed to provide a preparation method of dragdorff optimizing reagent and a method for testing the rejection rate of ultrafiltration membrane.
Disclosure of Invention
The invention aims to provide a preparation method of Dragendorff optimized reagent and an ultrafiltration membrane rejection rate test method, which are used for solving the technical problems that the preparation method of Dragendorff optimized reagent is used for solving the technical problems that the rejection rate of a membrane product to polyethylene glycol is determined by a spectrophotometry in the prior art, and when the concentration of polyethylene glycol is determined by a conventional D reagent method, the D reagent is not resistant to visible light, is easy to oxidize and store, and is inaccurate in determination result and poor in experimental repeatability.
The preparation method of the dragdorff optimizing reagent provided by the invention comprises the following steps:
Preparing bismuth subnitrate solution with the concentration of 80 g/L;
Respectively weighing potassium iodide, iodine and water, mixing, transferring into a brown volumetric flask, and shaking uniformly to obtain iodine-containing mixed solution, wherein the mass ratio of potassium iodide to iodine to water is 4 (1-1.5): 5;
and mixing bismuth subnitrate solution, iodine-containing mixed solution, anhydrous acetic acid and water according to the volume ratio of 0.5:10:20:69.5, and shaking uniformly to obtain the Dragendorff optimizing reagent.
Preferably, bismuth subnitrate has a molecular formula of Bi (O) NO 3 and a molecular weight of 287..
The invention also provides a method for testing the rejection rate of the ultrafiltration membrane, which comprises the following steps:
Preparing an acetic acid-sodium acetate buffer solution with ph=4.8;
Preparing the dragdorff optimized reagent by adopting the preparation method of the dragdorff optimized reagent;
Preparing a plurality of polyethylene glycol standard solutions with concentration gradients by adopting polyethylene glycol, taking 5mL of each polyethylene glycol standard solution, respectively placing the 5mL of each polyethylene glycol standard solution into a 10mL volumetric flask, adding 1mL of acetic acid-sodium acetate buffer solution with pH of 4.8 and 1mL of dragdorff optimizing reagent into each standard solution with concentration, and adding water to fix the volume to obtain a plurality of marking solutions with concentration gradients;
Testing a plurality of marked line solutions with concentration gradients by using a spectrophotometer to obtain a standard curve;
Preparing polyethylene glycol test solution, passing the polyethylene glycol test solution through an ultrafiltration membrane to obtain polyethylene glycol filtrate, obtaining the concentration of the polyethylene glycol test solution and the concentration of the polyethylene glycol filtrate through a standard curve, and obtaining the retention rate of the ultrafiltration membrane according to R= (1-C p/Cf) x 100%;
wherein, C p is the concentration of polyethylene glycol filtrate; c f is the concentration of the polyethylene glycol test solution.
Preferably, the ph=4.8 acetic acid-sodium acetate buffer solution configuration process comprises:
59mL of a 0.2 mL/L sodium acetate solution and 41mL of a 0.2 mL/L acetic acid solution were removed and placed in a 100mL volumetric flask to obtain an acetic acid-sodium acetate buffer solution having pH=4.8.
Preferably, the polyethylene glycol "concentration-absorbance" standard curve concentration range is 5-30mg/L.
Preferably, dragdorff optimizing reagent for one day is selected, standard test solution is prepared and tested, and the obtained curve equation y=0.0435x+0.3853 and r2=0.9995;
Eight days of dragdorff optimizing reagent was selected, and standard test solutions were prepared and tested to obtain the curve equation y=0.00411x+0.4083, r2=0.9994.
Preferably, the ultrafiltration membrane rejection test method is applicable to ultrafiltration membranes made of cellulose, modified cellulose, polyethersulfone, polysulfone, sulfonated polysulfone or polyvinylidene fluoride.
Preferably, the ultrafiltration membrane rejection test method is applicable to ultrafiltration membranes of roll, hollow fiber, tubular, plate and frame or curtain configurations.
Preferably, the ultrafiltration membrane rejection rate test is performed by adopting a membrane test device, the membrane test device comprises a constant temperature storage tank, a water outlet of the constant temperature storage tank is communicated with a water inlet of a membrane element through a first pipeline, the water outlet of the membrane element is communicated with the water inlet of the constant temperature storage tank through a second pipeline, a first regulating valve, a first peristaltic pump and a first pressure gauge are arranged on the first pipeline, a second pressure gauge, a flowmeter and a second regulating valve are arranged on the second pipeline, and a filtrate water outlet of the membrane element is communicated with a filtrate collecting tank through a third pipeline.
Preferably, a cross-flow filtration mode is adopted to operate the membrane testing device, the transmembrane pressure difference is 0.10MPa, the membrane surface flow rate is not lower than 0.25m/s, the filtrate and the feed liquid are collected after the membrane testing device is stably operated for more than or equal to 30 minutes, and the absorbance values of the filtrate and the feed liquid are measured at the wavelength of 510nm, so that the rejection rate is obtained.
Compared with the prior art, the preparation method of the Dragendorff optimizing reagent and the ultrafiltration membrane interception rate testing method provided by the invention have the following steps:
1. According to the preparation method of the Dragendorff optimized reagent, the optimized Dragendorff reagent formula and the determination method, the problems that the reagent D is easy to oxidize and the stability is poor are effectively solved due to the addition of potassium iodide and iodine, the accuracy of a test result is ensured, the stability of a color reagent is improved, and the storage time is prolonged.
2. According to the ultrafiltration membrane rejection rate testing method provided by the invention, dragdorff optimized reagents are selected, the standard curve has good linear relation in a certain concentration range, the testing result is reliable, the cost is low, and the operation is simple.
3. The ultrafiltration membrane rejection rate testing method provided by the invention has the advantages of simple operation flow and low input cost.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a step chart of a method for testing the rejection rate of an ultrafiltration membrane according to the invention;
FIG. 2 is a schematic diagram of a membrane testing apparatus according to the present invention.
Reference numerals illustrate:
1. constant temperature liquid storage tank; 2. a first regulating valve; 3. a peristaltic pump; 4. a first pressure gauge; 5. a membrane element; 6. a filtrate collection tank; 7. a second pressure gauge; 8-a flowmeter; 9. a second regulating valve; 10. a first pipeline; 11. a second pipeline; 12. and a third pipeline.
Detailed Description
The following description of the embodiments of the present invention will be made apparent and fully in view of the accompanying drawings, in which some, but not all embodiments of the invention are shown. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience of describing the present invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
The preparation method of the dragdorff optimizing reagent provided by the invention comprises the following steps:
Preparing bismuth subnitrate solution with the concentration of 80 g/L;
Respectively weighing potassium iodide, iodine and water, mixing, transferring into a brown volumetric flask, and shaking uniformly to obtain iodine-containing mixed solution, wherein the mass ratio of potassium iodide to iodine to water is 4 (1-1.5): 5;
and mixing bismuth subnitrate solution, iodine-containing mixed solution, anhydrous acetic acid and water according to the volume ratio of 0.5:10:20:69.5, and shaking uniformly to obtain the Dragendorff optimizing reagent.
Bismuth subnitrate of the present invention has a molecular formula of Bi (O) NO 3 and a molecular weight of 287..
As shown in FIG. 1, the invention also provides a method for testing the rejection rate of the ultrafiltration membrane, which comprises the following steps:
s1) preparing an acetic acid-sodium acetate buffer solution with ph=4.8;
S2) preparing dragdorff optimized reagent using the preparation method of dragdorff optimized reagent as described in claim 1 or 2;
S3) preparing a plurality of polyethylene glycol standard solutions with concentration gradients by adopting polyethylene glycol, taking 5mL of each polyethylene glycol standard solution, respectively placing the 5mL of each polyethylene glycol standard solution into a 10mL volumetric flask, adding 1mL of acetic acid-sodium acetate buffer solution with pH of 4.8 and 1mL of Dragendorff optimizing reagent into each standard solution with concentration, and adding water to fix the volume to obtain a plurality of marking solutions with concentration gradients;
S4) testing a plurality of marked line solutions with concentration gradients by using a spectrophotometer to obtain a standard curve;
S5) preparing polyethylene glycol test solution, passing the polyethylene glycol test solution through an ultrafiltration membrane to obtain polyethylene glycol filtrate, obtaining the concentration of the polyethylene glycol test solution and the concentration of the polyethylene glycol filtrate through a standard curve, and obtaining the retention rate of the ultrafiltration membrane according to R= (1-C p/Cf) x 100%;
wherein, C p is the concentration of polyethylene glycol filtrate; c f is the concentration of the polyethylene glycol test solution.
Specifically, the ph=4.8 acetic acid-sodium acetate buffer solution configuration process includes:
59mL of a 0.2 mL/L sodium acetate solution and 41mL of a 0.2 mL/L acetic acid solution were removed and placed in a 100mL volumetric flask to obtain an acetic acid-sodium acetate buffer solution having pH=4.8.
Specifically, the concentration range of the polyethylene glycol concentration-absorbance standard curve is 5-30mg/L.
Specifically, dragdorff optimizing reagent for one day is selected, standard test solution is configured and tested, and the obtained curve equation y=0.0435x+0.3853 and r2=0.9995;
Eight days of dragdorff optimizing reagent was selected, and standard test solutions were prepared and tested to obtain the curve equation y=0.00411x+0.4083, r2=0.9994.
Specifically, the ultrafiltration membrane rejection rate test method is suitable for ultrafiltration membranes made of cellulose, modified cellulose, polyether sulfone, polysulfone, sulfonated polysulfone or polyvinylidene fluoride.
Specifically, the ultrafiltration membrane rejection rate test method is applicable to ultrafiltration membranes in roll, hollow fiber, tubular, plate-and-frame or curtain configurations.
The invention adopts a membrane testing device to carry out ultrafiltration membrane retention rate test, the membrane testing device comprises a constant temperature storage tank 1, a water outlet of the constant temperature storage tank 1 is communicated with a water inlet of a membrane element 5 through a first pipeline 10, a water outlet of the membrane element 5 is communicated with a water inlet of the constant temperature storage tank 1 through a second pipeline 11, a first regulating valve 2, a first peristaltic pump 3 and a first pressure gauge 4 are arranged on the first pipeline, a second pressure gauge 7, a flowmeter 8 and a second regulating valve 9 are arranged on the second pipeline, and a filtrate water outlet of the membrane element 5 is communicated with a filtrate collecting tank 6 through a third pipeline 12.
Specifically, a cross-flow filtration mode is adopted to operate a membrane testing device, the transmembrane pressure difference is 0.10MPa, the membrane surface flow rate is not lower than 0.25m/s, filtrate and feed liquid are collected after the membrane testing device is stably operated for more than or equal to 30 minutes, and the absorbance values of the filtrate and the feed liquid are measured at the wavelength of 510nm, so that the rejection rate is obtained.
According to the preparation method of the Dragendorff optimized reagent, the optimized formula of the reagent D and the determination method, the problems of easiness in oxidation and poor stability of the reagent D are effectively solved due to the addition of potassium iodide and iodine, the accuracy of a test result is ensured, the stability of a color developing agent is improved, and the storage time is prolonged.
According to the ultrafiltration membrane rejection rate testing method provided by the invention, dragdorff optimized reagents are selected, the standard curve has good linear relation in a certain concentration range, the testing result is reliable, the cost is low, and the operation is simple.
The ultrafiltration membrane rejection rate testing method provided by the invention has the advantages of simple operation flow and low input cost.
The membrane testing device provided by the invention can collect the filtrate and the feed liquid after the stable operation time is more than or equal to 30 minutes, so that the testing result can be ensured to be more accurate.
In some examples, 59mL of 0.2 mL/L sodium acetate solution and 41mL of 0.2 mL/L acetic acid solution were accurately removed in the experiment and placed in a 100mL volumetric flask to prepare an acetic acid-sodium acetate buffer solution at ph=4.8.
Preparing Dragendorff optimizing reagent and bismuth subnitrate solution with concentration of 80 g/L;
respectively weighing 20g of potassium iodide, 5g of iodine and 25g of water, mixing, transferring into a brown volumetric flask, and shaking uniformly to obtain iodine-containing mixed solution;
Mixing bismuth subnitrate solution, iodine-containing mixed solution, anhydrous acetic acid and water according to the volume ratio of 0.5:10:20:69.5, and shaking uniformly to obtain Dragendorff optimizing reagent;
Selecting polyethylene glycol with molecular weight of 10000, placing the polyethylene glycol into a vacuum drying oven with temperature of 40 ℃ before use, vacuum drying to constant weight, accurately weighing 10000.000 g of dried PEG, placing into a 50mL beaker, adding water for dissolution, transferring into a 1000mL volumetric flask, fixing volume, and shaking uniformly to obtain 1000mg/L polyethylene glycol solution; transferring 1000mg/L of polyethylene glycol solution into 100mL volumetric flasks, respectively, adding water to scale marks, and shaking uniformly to prepare polyethylene glycol standard solutions with mass concentrations of 5mg/L, 10mg/L, 15mg/L, 20mg/L, 25mg/L and 30mg/L, wherein the polyethylene glycol standard solutions are respectively 1.0mL, 1.5mL, 2.0mL, 2.5mL and 3.0 mL; transferring 5.0mL of the prepared standard solution without concentration into a 10mL volumetric flask, adding 1mL of acetic acid-sodium acetate buffer solution with pH=4.8, adding 1mL of dragdorff optimizing reagent, shaking uniformly, adding water for dilution to a scale, and standing in a dark place for 15min to obtain a plurality of marking solutions;
The absorbance values of the solutions of different concentrations of the markings were determined on an ultraviolet-visible spectrophotometer with a 1cm cuvette at a wavelength of 510nm, using distilled water as a reference. Preparing a standard test solution by using a Dragendorff optimizing reagent on the 1 st day and 8 th days of storage with the polyethylene glycol concentration as an abscissa and the absorbance value as an ordinate, wherein the obtained standard curves have good linear relations; the curve equation y=0.0435x+0.3853, r2=0.9995 was obtained using dragdorff optimized reagent for 1 day; the curve equation y=0.00411x+0.4083, r2=0.9994 was obtained using the dragdorff optimized reagent for 8 days.
The ultrafiltration membrane rejection rate test is carried out by adopting a membrane test device, the membrane test device comprises a constant temperature storage tank 1, a water outlet of the constant temperature storage tank 1 is communicated with a water inlet of a membrane element 5 through a first pipeline 10, a water outlet of the membrane element 5 is communicated with a water inlet of the constant temperature storage tank 1 through a second pipeline, a first regulating valve 2, a first peristaltic pump 3 and a first pressure gauge 4 are arranged on the first pipeline, a second pressure gauge 7, a flowmeter 8 and a second regulating valve 9 are arranged on the second pipeline of the first peristaltic pump 3 and the first pressure gauge 4, and a filtrate water outlet of the membrane element 5 is communicated with a filtrate collection tank 6 through a third pipeline (12); preparing polyethylene glycol test solution, operating a membrane test device in a cross-flow filtration mode, wherein the transmembrane pressure difference is 0.10MPa, the membrane surface flow rate is not lower than 0.25m/s, collecting filtrate and feed solution after the membrane test device is stably operated for more than or equal to 30 minutes, measuring absorbance values of the filtrate and the feed solution at the wavelength of 510nm, obtaining polyethylene glycol test solution concentration and polyethylene glycol filtrate concentration according to a standard curve, and obtaining ultrafiltration membrane retention rate according to R= (1-C p/Cf) x 100%; wherein, C p is the concentration of polyethylene glycol filtrate; c f is the concentration of the polyethylene glycol test solution.
When the interception of the ultra-micro filter membrane to the polyethylene glycol is measured, the dragndorff reagent serving as a color reagent is subjected to formula improvement, so that the stability of the reagent is improved. And drawing a polyethylene glycol concentration-absorbance standard curve. The membrane test device is operated in a cross-flow filtration mode, the transmembrane pressure difference is 0.10MPa, the membrane surface flow rate is not lower than 0.25m/s, the filtrate and the feed liquid are collected after the system is stably operated for a certain time, and the absorbance value of the solution is measured at the wavelength of 510nm, so that the rejection rate is obtained.
The dragdorff reagent is optimized, the reagent is stable, the storage time is long, and the reproducibility of the interception rate measurement result is good.
The invention provides an ultrafiltration membrane rejection rate testing method with low cost and good reproducibility, which uses polyethylene glycol as a reference substance to optimize a dragndorff reagent formula, so that the stability of the dragndorff reagent is improved, the rejection rate result reliability is further improved, and a set of simple ultrafiltration membrane rejection rate testing device flow is provided.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.
Claims (10)
1. A preparation method of Dragendorff optimizing reagent is characterized by comprising the following steps: the method comprises the following steps:
Preparing bismuth subnitrate solution with the concentration of 80 g/L;
Respectively weighing potassium iodide, iodine and water, mixing, transferring into a brown volumetric flask, and shaking uniformly to obtain iodine-containing mixed solution, wherein the mass ratio of the potassium iodide to the iodine to the water is 4:1:5;
and mixing bismuth subnitrate solution, iodine-containing mixed solution, anhydrous acetic acid and water according to the volume ratio of 0.5:10:20:69.5, and shaking uniformly to obtain the Dragendorff optimizing reagent.
2. The method for preparing Dragendorff optimizing reagent as claimed in claim 1, wherein: bismuth subnitrate has a molecular formula of Bi (O) NO 3 and a molecular weight of 287.
3. A method for testing the rejection rate of an ultrafiltration membrane is characterized by comprising the following steps: the method comprises the following steps:
Preparing an acetic acid-sodium acetate buffer solution with ph=4.8;
preparing dragdorff optimized reagent using the preparation method of dragdorff optimized reagent as described in claim 1 or 2;
Preparing a plurality of polyethylene glycol standard solutions with concentration gradients by adopting polyethylene glycol, taking 5mL of each polyethylene glycol standard solution, respectively placing the 5mL of each polyethylene glycol standard solution into a 10mL volumetric flask, adding 1mL of acetic acid-sodium acetate buffer solution with pH of 4.8 and 1mL of dragdorff optimizing reagent into each standard solution with concentration, and adding water to fix the volume to obtain a plurality of marking solutions with concentration gradients;
Testing a plurality of marked line solutions with concentration gradients by using a spectrophotometer to obtain a standard curve;
Preparing polyethylene glycol test solution, passing the polyethylene glycol test solution through an ultrafiltration membrane to obtain polyethylene glycol filtrate, obtaining the concentration of the polyethylene glycol test solution and the concentration of the polyethylene glycol filtrate through a standard curve, and obtaining the retention rate of the ultrafiltration membrane according to R= (1-C p/Cf) x 100%;
wherein, C p is the concentration of polyethylene glycol filtrate; c f is the concentration of the polyethylene glycol test solution.
4. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein: the ph=4.8 acetic acid-sodium acetate buffer solution configuration procedure included:
59mL of a 0.2mol/L sodium acetate solution and 41mL of a 0.2mol/L acetic acid solution were removed and placed in a 100mL volumetric flask to obtain an acetic acid-sodium acetate buffer solution having pH=4.8.
5. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein: the concentration range of the polyethylene glycol concentration-absorbance standard curve is 5-30mg/L.
6. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein:
selecting dragdorff optimizing reagent for one day, and configuring and testing standard test solution to obtain a curve equation Y=0.0435X+0.3853 and R2=0.9995;
Eight days of dragdorff optimizing reagent was selected, and standard test solutions were prepared and tested to obtain the curve equation y=0.00411x+0.4083, r2=0.9994.
7. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein: the ultrafiltration membrane interception rate test method is suitable for ultrafiltration membranes made of cellulose, modified cellulose, polyether sulfone, polysulfone, sulfonated polysulfone or polyvinylidene fluoride.
8. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein: the ultrafiltration membrane interception rate testing method is suitable for ultrafiltration membranes in roll type, hollow fiber type, tubular type, plate frame type or curtain type configurations.
9. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein: adopt membrane testing arrangement to carry out milipore filter interception rate test, membrane testing arrangement includes constant temperature holding tank (1), constant temperature holding tank (1) delivery port is through first pipeline (10) and membrane element (5) water inlet intercommunication, membrane element (5) delivery port is through second pipeline (11) and constant temperature holding tank (1) water inlet intercommunication, install first governing valve (2) on first pipeline (10), first peristaltic pump (3) and first manometer (4), install second manometer (7) on second pipeline (11), flowmeter (8) and second governing valve (9), membrane element (5) filtrate delivery port are through third pipeline (12) and filtrate collecting tank (6) intercommunication.
10. The ultrafiltration membrane rejection rate testing method according to claim 3, wherein: and (3) operating the membrane testing device in a cross-flow filtration mode, wherein the transmembrane pressure difference is 0.10MPa, the membrane surface flow rate is not lower than 0.25m/s, collecting filtrate and feed liquid after the membrane testing device is stably operated for more than or equal to 30 minutes, and measuring the absorbance values of the filtrate and the feed liquid at the wavelength of 510nm so as to obtain the rejection rate.
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