Method for measuring COD (Chemical Oxygen Demand) value of glass raw material

Abstract

The invention discloses a method for measuring a COD value of a glass raw material and belongs to the technical field of chemical analysis. The method comprises the following steps: mixing a to-be-detected sample, a first potassium dichromate solution, a first catalyst and first concentrated sulfuric acid to obtain a to-be-detected mixture; performing first sealing digestion on the to-be-detected mixture to obtain a to-be-detected digestion solution; performing a first spectrophotometric test on the digestion solution to be tested to obtain an absorbance value of the sample to be tested; obtaining a standard working curve; substituting the absorbance value of the to-be-detected sample into the standard working curve to obtain a COD (Chemical Oxygen Demand) value; digestion is performed in a sealed digestion manner, so that the reaction can be quickly and fully performed, the detection time can be shortened, and the COD value of the glass raw material can be quickly measured in a large scale by matching with spectrophotometric test. Moreover, chloride ions can be oxidized into chlorine gas in a sealed digestion mode, gas-liquid balance is achieved, the chlorine gas cannot be oxidized again, the problem of chloride ion interference can be solved under the condition that masking agents such as mercury sulfate are not used, and toxicity and secondary pollution to the environment are reduced.

Description

Technical Field

[0001] The present application relates to the technical field of chemical analysis, and in particular to a method for determining the COD value of glass raw materials. Background Art

[0002] COD is the abbreviation of Chemical Oxygen Demand. It means that the various raw materials that make up the glass batch contain different levels of carbon or organic matter. These substances play the same role as carbon powder in the melting process of the batch, affecting the melting atmosphere in the glass melting furnace. These carbon-containing substances are converted into ppmC through a certain test method, and the measured value is called COD value.

[0003] Photovoltaic glass is ultra-white glass with high light transmittance and transparency. It requires low iron content and is difficult to clarify during production. The COD value has a certain influence on the melting, homogenization and clarification quality of photovoltaic glass, so it is necessary to test and control the COD of photovoltaic glass raw materials and batches.

[0004] The current COD value test method is potassium dichromate titration, which specifically includes: in a concentrated sulfuric acid environment, using silver sulfate as a catalyst, mercuric sulfate as a chloride ion masking agent, using excess potassium dichromate to oxidize the reducing substances in the sample, and after sufficient heating and reflux, using ferrochlore as an indicator, using ammonium ferrous sulfate standard solution to back-titrate the excess potassium dichromate, thereby calculating the COD value in the sample. This method has the advantages of being simple, stable and accurate, but it also has the disadvantages of long reflux time, high catalyst cost, high toxicity of the chloride ion masking agent, and secondary pollution. Summary of the invention

[0005] The present application provides a method for determining the COD value of glass raw materials, which can realize rapid and accurate COD value detection under low pollution conditions.

[0006] The present application provides a method for determining the COD value of glass raw materials, the method comprising:

[0007] Mixing the sample to be tested, the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid to obtain a mixture to be tested;

[0008] Performing a first sealed digestion on the mixture to be tested to obtain a digestion solution to be tested;

[0009] Performing a first spectrophotometric test on the digestion solution to be tested to obtain an absorbance value of the sample to be tested;

[0010] A standard working curve with COD value and absorbance value as horizontal and vertical coordinates is obtained;

[0011] The absorbance value of the sample to be tested is brought into the standard working curve to obtain the COD value of the sample to be tested.

[0012] As an optional embodiment, the temperature of the first seal digestion is 140° C. to 170° C.; and / or

[0013] The first seal digestion time is 15 minutes to 25 minutes.

[0014] As an optional embodiment, the first catalyst includes potassium aluminum sulfate.

[0015] As an optional embodiment, the molar concentration of the first potassium dichromate solution is 0.1 mol / mL to 0.3 mol / mL, and the amount of the first potassium dichromate solution is 1 mL to 3 mL; and / or

[0016] The mass concentration of the first catalyst is 3 g / L to 5 g / L, and the amount of the first catalyst is 3 mL to 5 mL; and / or

[0017] The amount of the first concentrated sulfuric acid is 7 mL to 9 mL; and / or

[0018] The ratio of the weight value of the sample to be tested in g to the total volume value of the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid in mL is (0.5-2):14.

[0019] As an optional implementation manner, the test wavelength of the first spectrophotometric test is 600nm-620nm.

[0020] As an optional implementation manner, the mass percentage content of chloride ions in the sample to be tested is not higher than 0.5%.

[0021] As an optional embodiment, the obtaining of a standard working curve with COD value and absorbance value as horizontal and vertical coordinates includes:

[0022] Obtain multiple standard working test solutions with different COD values;

[0023] mixing each of the standard working test solutions with a second potassium dichromate solution, a second catalyst, and a second concentrated sulfuric acid to obtain a plurality of standard mixtures;

[0024] Performing a second sealed digestion on the plurality of standard mixtures respectively to obtain a plurality of standard digestion solutions;

[0025] Performing a second spectrophotometric test on each of the plurality of standard digestion solutions to obtain a plurality of standard absorbance values;

[0026] According to the COD value of each standard working test solution and its corresponding standard absorbance value, a standard working curve with COD value and absorbance value as horizontal and vertical coordinates is obtained.

[0027] As an optional implementation, the COD values ​​of the plurality of standard working test solutions are 0 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 400 mg / L and 800 mg / L, respectively.

[0028] As an optional embodiment, the amount of the standard working test solution is 1 mL to 3 mL; and / or

[0029] The concentration and dosage of the second potassium dichromate solution are the same as those of the first potassium dichromate solution; and / or

[0030] The concentration and amount of the second catalyst are the same as those of the first catalyst; and / or

[0031] The usage of the second concentrated sulfuric acid is the same as that of the first concentrated sulfuric acid.

[0032] As an optional implementation, the process parameters of the second sealed digestion are the same as those of the first sealed digestion; and / or

[0033] The process parameters of the second spectrophotometric test are the same as those of the first spectrophotometric test.

[0034] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0035] The method provided in the embodiment of the present application can make the reaction proceed quickly and fully by using a sealed digestion method, can shorten the detection time, and can quickly determine the COD value of glass raw materials in large quantities in conjunction with spectrophotometric testing. In addition, the chloride ion content in glass is usually low, and the sealed digestion method can oxidize the chloride ions into chlorine gas and reach gas-liquid equilibrium, which cannot be oxidized again. In the case of not using masking agents such as mercuric sulfate, the chloride ion interference problem can be solved, and the toxicity and secondary pollution to the environment can be reduced. Therefore, this method can achieve rapid and accurate COD value detection under low pollution conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0037] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0038] Figure 1 A flowchart of the method provided in the embodiment of the present application. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0040] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0041] The current COD value test method for glass has the disadvantages of long reflux time, high catalyst cost, high toxicity of chloride ion masking agent, and secondary pollution. To this end, the present application intends to provide a method for measuring the COD value of glass raw materials, which uses potassium aluminum sulfate instead of silver sulfate as a catalyst to reduce the measurement cost; uses sealed digestion to oxidize chloride ions into chlorine gas and reach gas-liquid equilibrium, which can no longer be oxidized, can solve the problem of chloride ion interference, avoid the use of mercuric sulfate, reduce toxicity and pollution, and digest quickly; the test adopts spectrophotometry, which has a long use time after drawing the curve, and can quickly measure the COD value in glass raw materials and batches in large quantities.

[0042] Figure 1 A flow chart of the method provided in the embodiment of the present application is as follows: Figure 1 As shown, the embodiment of the present application provides a method for determining the COD value of glass raw materials, the method comprising:

[0043] S1. The sample to be tested, the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid are mixed to obtain a mixture to be tested;

[0044] In some embodiments, the first catalyst includes potassium aluminum sulfate. By using potassium aluminum sulfate as a catalyst, expensive silver sulfate is replaced, and the cost is reduced. It can be understood by those skilled in the art that in other embodiments, the first catalyst can also be one or more of nickel sulfate, manganese dihydrogen phosphate, copper sulfate, etc., instead of silver sulfate as a catalyst to achieve the purpose of reducing costs.

[0045] In some embodiments, the molar concentration of the first potassium dichromate solution is 0.1mol / mL to 0.3mol / mL, and the amount of the first potassium dichromate solution is 1mL to 3mL; the mass concentration of the first catalyst is 3g / L to 5g / L, and the amount of the first catalyst is 3mL to 5mL; the amount of the first concentrated sulfuric acid is 7mL to 9mL; the ratio of the weight value of the sample to be tested in g to the total volume value of the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid in mL is (0.5 to 2): 14. Exemplarily, the molar concentration of the first potassium dichromate solution can be 0.1mol / mL, 0.2mol / mL, 0.3mol / mL, etc., and it can also be any value in the range of 0.1mol / mL to 0.3mol / mL. The amount of the first potassium dichromate solution can be 1mL, 2mL, 3mL, etc., and it can also be any value in the range of 1mL to 3mL. The mass concentration of the first catalyst can be 3g / L, 4g / L, 5g / L, etc., and it can also be any value within the range of 3g / L to 5g / L. The dosage of the first catalyst can be 3mL, 4mL, 5mL, etc., and it can also be any value within the range of 3mL to 5mL. The dosage of the first concentrated sulfuric acid can be 7mL, 8mL, 9mL, etc., and it can also be any value within the range of 7mL to 9mL. The ratio of the weight value of the sample to be tested in g to the total volume value of the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid in mL can be 0.5:14, 1:14, 1.5:14, 2:14, etc., and it can also be any value within the range of (0.5 to 2):14. It should be noted that concentrated sulfuric acid refers to an aqueous sulfuric acid solution with a mass fraction greater than or equal to 70%.

[0046] Specifically, in this embodiment, the dosage of each substance can be: 0.5-2 g of the sample to be tested, the concentration of the first potassium dichromate solution is 0.2 mol / mL, and the dosage volume is 2 mL; the concentration of the first potassium aluminum sulfate catalyst is 4 g / L, and the dosage volume is 4 mL, and the volume of concentrated sulfuric acid is 8 mL.

[0047] In some embodiments, the mass percentage of chloride ions in the sample to be tested is not higher than 0.5%.

[0048] S2. performing a first sealed digestion on the mixture to be tested to obtain a digestion solution to be tested;

[0049] It should be noted that sealed digestion refers to digestion performed in a closed space, for example, digestion can be performed in a digestion tank.

[0050] In some embodiments, the temperature for digestion of the first seal is 140°C to 170°C; the time for digestion of the first seal is 15min to 25min. Exemplarily, the temperature for digestion of the first seal can be 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, etc., and it can also be any value within the range of 140°C to 170°C. The time for digestion of the first seal can be 15min, 16min, 17min, 18min, 19min, 20min, 21min, 22min, 23min, 24min, 25min, etc., and it can also be any value within the range of 15min to 25min.

[0051] Specifically, in this embodiment, the preparation process of the digestion solution to be tested can be: weigh an appropriate amount of the sample to be tested in a digestion tank, add a small amount of deionized water to moisten and disperse it, add a first potassium dichromate solution, a first potassium aluminum sulfate catalyst and a first concentrated sulfuric acid, cover tightly and shake well, then turn on the microwave digestion instrument, set the temperature to 165°C, until the digestion is complete, and obtain the digestion solution to be tested.

[0052] S3. Performing a first spectrophotometric test on the digestion solution to be tested to obtain an absorbance value of the sample to be tested;

[0053] In some embodiments, the test wavelength of the first spectrophotometric test is 600nm-620nm. Exemplarily, the test wavelength of the first spectrophotometric test can be 600nm, 605nm, 610nm, 615nm, 620nm, etc., and can also be any value within the range of 600nm-620nm.

[0054] Specifically, in this embodiment, the digestion solution to be tested is transferred to a colorimetric tube (the colorimetric tube is 50 mL), the volume to be tested is fixed, and then the ultraviolet visible spectrophotometer is turned on, the wavelength is set, and the spectrophotometer is used for testing to obtain the absorbance value of the sample to be tested. Among them, the wavelength is 610 nm.

[0055] S4. Obtain a standard working curve with COD value and absorbance as horizontal and vertical coordinates;

[0056] In some embodiments, obtaining a standard working curve with COD value and absorbance value as horizontal and vertical coordinates includes:

[0057] S4.1. Obtain multiple standard working test solutions with different COD values;

[0058] S4.2. The standard working test solutions are mixed with the second potassium dichromate solution, the second catalyst and the second concentrated sulfuric acid to obtain a plurality of standard mixtures;

[0059] S4.3. Perform a second sealed digestion on the plurality of standard mixtures to obtain a plurality of standard digestion solutions;

[0060] S4.4. Perform a second spectrophotometric test on each of the plurality of standard digestion solutions to obtain a plurality of standard absorbance values;

[0061] S4.5. According to the COD value of each standard working test solution and its corresponding standard absorbance value, a standard working curve with COD value and absorbance value as horizontal and vertical coordinates is obtained.

[0062] The COD values ​​of the plurality of standard working test solutions are 0 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 400 mg / L and 800 mg / L, respectively. The dosage of the standard working test solution is 1 mL to 3 mL.

[0063] The process parameters during the entire standard absorbance value test are the same as the process parameters of the absorbance value of the sample to be tested, for example, the concentration and dosage of the second potassium dichromate solution are the same as those of the first potassium dichromate solution; the concentration and dosage of the second catalyst are the same as those of the first catalyst; the dosage of the second concentrated sulfuric acid is the same as that of the first concentrated sulfuric acid; the process parameters of the second sealed digestion are the same as those of the first sealed digestion; and the process parameters of the second spectrophotometric test are the same as those of the first spectrophotometric test.

[0064] Specifically, in the present embodiment, the acquisition process of the whole quasi-working curve can be to dissolve constant volume with potassium hydrogen phthalate reference reagent to obtain COD stock solution. Get a series of above-mentioned stock solutions respectively, and a series of standard working test solutions of different COD values ​​can be obtained. In a digestion tank, add the above-mentioned standard working test solution respectively, add the second potassium dichromate solution, the second potassium aluminum sulfate catalyst and the second concentrated sulfuric acid, cover tightly and shake up, digest in a microwave digestion instrument, cool and transfer to a colorimetric tube, constant volume to be measured. Then open the ultraviolet visible spectrophotometer, set the wavelength, pour each standard liquid to be measured into the colorimetric dish successively, measure absorbance, take the COD value as the horizontal coordinate, and the absorbance value as the vertical coordinate, draw the standard working curve. Among them, the concentration of COD stock solution is 1000mg / L, the COD values ​​of standard working test solutions are 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L respectively; the volume of standard working test solution is 2mL; the wavelength is 610nm, and the length of the cuvette is 3cm.

[0065] It is understandable that the standard working curve can be drawn each time the COD value of the sample to be tested is measured, but in order to quickly measure the COD value of the sample to be tested in large quantities, the same standard working curve can be used without changing the reagent batch, etc. It should be noted that the maximum use time of a standard working curve is usually one month.

[0066] S5. Substitute the absorbance value of the sample to be tested into the standard working curve to obtain the COD value of the sample to be tested.

[0067] This method uses a sealed digestion method to digest, which can make the reaction proceed quickly and fully, shorten the detection time, and cooperate with spectrophotometric testing to quickly determine the COD value of glass raw materials in large quantities. In addition, the chloride ion content in glass is usually low, and the sealed digestion method can oxidize the chloride ions into chlorine gas and reach gas-liquid equilibrium, which can no longer be oxidized. In the case of not using masking agents such as mercuric sulfate, the chloride ion interference problem can be solved, reducing toxicity and secondary pollution to the environment. Therefore, this method can achieve rapid and accurate COD value detection under low pollution conditions.

[0068] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0069] The soda ash raw material with a known COD value of 228 mg / kg was tested using the methods provided in the embodiments and comparative examples.

[0070] Example 1

[0071] A method for measuring the COD value of glass raw materials, the method comprising:

[0072] (1) Weigh 2 g of the soda ash sample to be tested in a digestion tank, add 2 mL of deionized water to moisten and disperse it, add 2 mL of 0.2 mol / L potassium dichromate solution, 4 mL of 4 g / L potassium aluminum sulfate catalyst, and 8 mL of concentrated sulfuric acid, cover tightly and shake well.

[0073] (2) Turn on the microwave digester, set the temperature to 165°C, and digest (1) for 20 minutes.

[0074] (3) Remove the digestion tank, cool it to room temperature, transfer the test solution into a colorimetric tube, and adjust the volume to be tested.

[0075] (4) Prepare COD standard working test solution, dissolve 0.8502g potassium hydrogen phthalate standard reagent in a 1000mL volumetric flask to obtain a stock solution with a COD value of 1000mg / L. Take 0mL, 5mL, 10mL, 20mL, 40mL, and 80mL of the above stock solution in a 100mL volumetric flask to obtain a series of standard working test solutions with COD values ​​of 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L.

[0076] (5) Add 2 mL of the above standard working test solution, 2 mL of 0.2 mol / L potassium dichromate digestion solution, and 4 mL of 4 g / L potassium aluminum sulfate catalyst to the digestion tank, cover tightly and shake well, digest at 165°C in a microwave digester for 15 min, cool and transfer to a colorimetric tube, and make up to volume for testing.

[0077] (6) Draw a standard working curve: Turn on the UV-visible spectrophotometer, set the wavelength to 610 nm, pour the series of test solutions in (5) into 3 cm cuvettes in turn, measure the absorbance, and draw a standard working curve with COD value as the horizontal axis and absorbance value as the vertical axis.

[0078] (7) Use a spectrophotometer to measure the test solution in (3) and substitute it into the working curve obtained in (6) to obtain the COD value of the sample.

[0079] Example 2

[0080] A method for measuring the COD value of glass raw materials, the method comprising:

[0081] (1) Weigh 2 g of the soda ash sample to be tested in a digestion tank, add 2 mL of deionized water to moisten and disperse it, add 2 mL of 0.2 mol / L potassium dichromate solution, 4 mL of 4 g / L potassium aluminum sulfate catalyst, and 8 mL of concentrated sulfuric acid, cover tightly and shake well.

[0082] (2) Turn on the microwave digester, set the temperature to 165°C, and digest (1) for 15 minutes.

[0083] (3) Remove the digestion tank, cool it to room temperature, transfer the test solution into a colorimetric tube, and adjust the volume to be tested.

[0084] (4) Prepare COD standard working test solution, dissolve 0.8502g potassium hydrogen phthalate standard reagent in a 1000mL volumetric flask to obtain a stock solution with a COD value of 1000mg / L. Take 0mL, 5mL, 10mL, 20mL, 40mL, and 80mL of the above stock solution in a 100mL volumetric flask to obtain a series of standard working test solutions with COD values ​​of 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L.

[0085] (5) Add 2 mL of the above standard working test solution, 2 mL of 0.2 mol / L potassium dichromate digestion solution, and 4 mL of 4 g / L potassium aluminum sulfate catalyst to the digestion tank, cover tightly and shake well, digest at 165°C in a microwave digester for 15 min, cool and transfer to a colorimetric tube, and make up to volume for testing.

[0086] (6) Draw a standard working curve: Turn on the UV-visible spectrophotometer, set the wavelength to 610 nm, pour the series of test solutions in (5) into 3 cm cuvettes in turn, measure the absorbance, and draw a standard working curve with COD value as the horizontal axis and absorbance value as the vertical axis.

[0087] (7) Use a spectrophotometer to measure the test solution in (3) and substitute it into the working curve obtained in (6) to obtain the COD value of the sample.

[0088] Example 3

[0089] A method for measuring the COD value of glass raw materials, the method comprising:

[0090] (1) Weigh 2 g of the soda ash sample to be tested in a digestion tank, add 2 mL of deionized water to moisten and disperse it, add 2 mL of 0.2 mol / L potassium dichromate solution, 4 mL of 4 g / L potassium aluminum sulfate catalyst, and 8 mL of concentrated sulfuric acid, cover tightly and shake well.

[0091] (2) Turn on the microwave digester, set the temperature to 165°C, and digest (1) for 15 minutes.

[0092] (3) Remove the digestion tank, cool it to room temperature, transfer the test solution into a colorimetric tube, and adjust the volume to be tested.

[0093] (4) Prepare COD standard working test solution, dissolve 0.8502g potassium hydrogen phthalate standard reagent in a 1000mL volumetric flask to obtain a stock solution with a COD value of 1000mg / L. Take 0mL, 5mL, 10mL, 20mL, 40mL, and 80mL of the above stock solution in a 100mL volumetric flask to obtain a series of standard working test solutions with COD values ​​of 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L.

[0094] (5) Add 2 mL of the above standard working test solution, 2 mL of 0.2 mol / L potassium dichromate digestion solution, and 4 mL of 4 g / L potassium aluminum sulfate catalyst to the digestion tank, cover tightly and shake well, digest at 165°C in a microwave digester for 15 min, cool and transfer to a colorimetric tube, and make up to volume for testing.

[0095] (6) Draw a standard working curve: Turn on the UV-visible spectrophotometer, set the wavelength to 610 nm, pour the series of test solutions in (5) into 3 cm cuvettes in turn, measure the absorbance, and draw a standard working curve with COD value as the horizontal axis and absorbance value as the vertical axis.

[0096] (7) Use a spectrophotometer to measure the test solution in (3) and substitute it into the working curve obtained in (6) to obtain the COD value of the sample.

[0097] Comparative Example 1

[0098] A method for measuring the COD value of glass raw materials, the method comprising:

[0099] (1) Weigh 2 g of the soda ash sample to be tested in a digestion tank, add 2 mL of deionized water to moisten and disperse it, add 2 mL of 0.2 mol / L potassium dichromate solution, 4 mL of 4 g / L potassium aluminum sulfate catalyst, and 8 mL of concentrated sulfuric acid, cover tightly and shake well.

[0100] (2) Turn on the microwave digester, set the temperature to 165°C, and digest (1) for 10 min.

[0101] (3) Remove the digestion tank, cool it to room temperature, transfer the test solution into a colorimetric tube, and adjust the volume to be tested.

[0102] (4) Prepare COD standard working test solution, dissolve 0.8502g potassium hydrogen phthalate standard reagent in a 1000mL volumetric flask to obtain a stock solution with a COD value of 1000mg / L. Take 0mL, 5mL, 10mL, 20mL, 40mL, and 80mL of the above stock solution in a 100mL volumetric flask to obtain a series of standard working test solutions with COD values ​​of 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L.

[0103] (5) Add 2 mL of the above standard working test solution, 2 mL of 0.2 mol / L potassium dichromate digestion solution, and 4 mL of 4 g / L potassium aluminum sulfate catalyst to the digestion tank, cover tightly and shake well, digest at 165°C in a microwave digester for 15 min, cool and transfer to a colorimetric tube, and make up to volume for testing.

[0104] (6) Draw a standard working curve: Turn on the UV-visible spectrophotometer, set the wavelength to 610 nm, pour the series of test solutions in (5) into 3 cm cuvettes in turn, measure the absorbance, and draw a standard working curve with COD value as the horizontal axis and absorbance value as the vertical axis.

[0105] Use a spectrophotometer to measure the test solution in (3), and substitute it into the working curve obtained in (6) to obtain the COD value of the sample.

[0106] Comparative Example 2

[0107] A method for measuring the COD value of glass raw materials, the method comprising:

[0108] (1) Weigh 2 g of the soda ash sample to be tested in a digestion tank, add 2 mL of deionized water to moisten and disperse it, add 2 mL of 0.2 mol / L potassium dichromate solution, and 8 mL of concentrated sulfuric acid, cover tightly and shake well.

[0109] (2) Turn on the microwave digester, set the temperature to 165°C, and digest (1) for 15 minutes.

[0110] (3) Remove the digestion tank, cool it to room temperature, transfer the test solution into a colorimetric tube, and adjust the volume to be tested.

[0111] (4) Prepare COD standard working test solution, dissolve 0.8502g potassium hydrogen phthalate standard reagent in a 1000mL volumetric flask to obtain a stock solution with a COD value of 1000mg / L. Take 0mL, 5mL, 10mL, 20mL, 40mL, and 80mL of the above stock solution in a 100mL volumetric flask to obtain a series of standard working test solutions with COD values ​​of 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L.

[0112] (5) Add 2 mL of the above standard working test solution, 2 mL of 0.2 mol / L potassium dichromate digestion solution, and 4 mL of 4 g / L potassium aluminum sulfate catalyst to the digestion tank, cover tightly and shake well, digest at 165°C in a microwave digester for 15 min, cool and transfer to a colorimetric tube, and make up to volume for testing.

[0113] (6) Draw a standard working curve: Turn on the UV-visible spectrophotometer, set the wavelength to 610 nm, pour the series of test solutions in (5) into 3 cm cuvettes in turn, measure the absorbance, and draw a standard working curve with COD value as the horizontal axis and absorbance value as the vertical axis.

[0114] (7) Use a spectrophotometer to measure the test solution in (3) and substitute it into the working curve obtained in (6) to obtain the COD value of the sample.

[0115] Comparative Example 3

[0116] A method for measuring the COD value of glass raw materials, the method comprising:

[0117] (1) Weigh 2 g of the soda ash sample to be tested, add 10 mL of deionized water to moisten and disperse it, add 2 mL of 0.2 mol / L potassium dichromate solution, 4 mL of 4 g / L potassium aluminum sulfate catalyst, and 8 mL of concentrated sulfuric acid, cover tightly and shake well.

[0118] (2) Turn on the microwave digester for non-enclosed digestion (i.e., digestion in an open environment), set the temperature to 165°C, and digest (1) for 15 minutes.

[0119] (3) Cool to room temperature, transfer the test solution into a colorimetric tube, and make up to volume for testing.

[0120] (4) Prepare COD standard working test solution, dissolve 0.8502g potassium hydrogen phthalate standard reagent in a 1000mL volumetric flask to obtain a stock solution with a COD value of 1000mg / L. Take 0mL, 5mL, 10mL, 20mL, 40mL, and 80mL of the above stock solution in a 100mL volumetric flask to obtain a series of standard working test solutions with COD values ​​of 0mg / L, 50mg / L, 100mg / L, 200mg / L, 400mg / L, and 800mg / L.

[0121] (5) Add 2 mL of the above standard working test solution, 2 mL of 0.2 mol / L potassium dichromate digestion solution, and 4 mL of 4 g / L potassium aluminum sulfate catalyst to the digestion tank, cover tightly and shake well, digest at 165°C in a microwave digester for 15 min, cool and transfer to a colorimetric tube, and make up to volume for testing.

[0122] (6) Draw a standard working curve: Turn on the UV-visible spectrophotometer, set the wavelength to 610 nm, pour the series of test solutions in (5) into 3 cm cuvettes in turn, measure the absorbance, and draw a standard working curve with COD value as the horizontal axis and absorbance value as the vertical axis.

[0123] (7) Use a spectrophotometer to measure the test solution in (3) and substitute it into the working curve obtained in (6) to obtain the COD value of the sample.

[0124] The test results of each embodiment and comparative example are shown in the following table:

[0125]

[0126] It can be seen from the above table that the method provided in the embodiment of the present application can be used to quickly and accurately detect the COD value of glass raw materials, and the results are accurate and reliable, which can meet the needs of industrial production.

[0127] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0128] In the present application, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the present specification, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that there may be three relationships, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items. For example, "at least one of a, b or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc, or abc, where a, b and c can be single or multiple.

[0129] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for measuring the COD value of glass raw materials, characterized in that: The method comprises: Mixing the sample to be tested, the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid to obtain a mixture to be tested; Performing a first sealed digestion on the mixture to be tested to obtain a digestion solution to be tested; Performing a first spectrophotometric test on the digestion solution to be tested to obtain an absorbance value of the sample to be tested; A standard working curve with COD value and absorbance value as horizontal and vertical coordinates is obtained; The absorbance value of the sample to be tested is substituted into the standard working curve to obtain the COD value of the sample to be tested.

2. The method for measuring the COD value of glass raw materials according to claim 1, characterized in that: The temperature of the first seal digestion is 140°C to 170°C; and / or The first seal digestion time is 15 minutes to 25 minutes.

3. The method for measuring the COD value of glass raw materials according to claim 1, characterized in that: The first catalyst includes potassium aluminum sulfate.

4. The method for measuring the COD value of glass raw materials according to claim 1, characterized in that: The molar concentration of the first potassium dichromate solution is 0.1 mol / mL to 0.3 mol / mL, and the amount of the first potassium dichromate solution is 1 mL to 3 mL; and / or The mass concentration of the first catalyst is 3 g / L to 5 g / L, and the amount of the first catalyst is 3 mL to 5 mL; and / or The amount of the first concentrated sulfuric acid is 7 mL to 9 mL; and / or The ratio of the weight value of the sample to be tested in g to the total volume value of the first potassium dichromate solution, the first catalyst and the first concentrated sulfuric acid in mL is (0.5-2):

14.

5. The method for measuring the COD value of glass raw materials according to claim 1, characterized in that: The test wavelength of the first spectrophotometric test is 600nm-620nm.

6. The method for measuring the COD value of glass raw materials according to claim 1, characterized in that: The mass percentage content of chloride ions in the sample to be tested is not higher than 0.5%.

7. The method for measuring the COD value of glass raw materials according to claim 1, characterized in that: The standard working curve obtained by taking COD value and absorbance value as horizontal and vertical coordinates comprises: Obtain multiple standard working test solutions with different COD values; mixing each of the standard working test solutions with a second potassium dichromate solution, a second catalyst, and a second concentrated sulfuric acid to obtain a plurality of standard mixtures; Performing a second sealed digestion on the plurality of standard mixtures respectively to obtain a plurality of standard digestion solutions; Performing a second spectrophotometric test on each of the plurality of standard digestion solutions to obtain a plurality of standard absorbance values; According to the COD value of each standard working test solution and its corresponding standard absorbance value, a standard working curve with COD value and absorbance value as horizontal and vertical coordinates is obtained.

8. The method for measuring the COD value of glass raw materials according to claim 7, characterized in that: The COD values ​​of the plurality of standard working test solutions are respectively 0 mg / L, 50 mg / L, 100 mg / L, 200 mg / L, 400 mg / L and 800 mg / L.

9. The method for measuring the COD value of glass raw materials according to claim 6, characterized in that: The amount of the standard working test solution is 1 mL to 3 mL; and / or The concentration and dosage of the second potassium dichromate solution are the same as those of the first potassium dichromate solution; and / or The concentration and dosage of the second catalyst are the same as those of the first catalyst; and / or The usage of the second concentrated sulfuric acid is the same as that of the first concentrated sulfuric acid.

10. The method for measuring the COD value of glass raw materials according to claim 6, characterized in that: The process parameters of the second sealed digestion are the same as those of the first sealed digestion; and / or The process parameters of the second spectrophotometric test are the same as those of the first spectrophotometric test.

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