CN113607725A - Method for determining ammonia nitrogen content in wastewater - Google Patents
Method for determining ammonia nitrogen content in wastewater Download PDFInfo
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- CN113607725A CN113607725A CN202110878024.7A CN202110878024A CN113607725A CN 113607725 A CN113607725 A CN 113607725A CN 202110878024 A CN202110878024 A CN 202110878024A CN 113607725 A CN113607725 A CN 113607725A
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- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 title claims abstract description 84
- 239000002351 wastewater Substances 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 45
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 66
- 238000002835 absorbance Methods 0.000 claims abstract description 38
- 238000010521 absorption reaction Methods 0.000 claims abstract description 23
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000004327 boric acid Substances 0.000 claims abstract description 16
- 239000007788 liquid Substances 0.000 claims abstract description 14
- 239000003153 chemical reaction reagent Substances 0.000 claims description 40
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- 239000003795 chemical substances by application Substances 0.000 claims description 11
- 230000000873 masking effect Effects 0.000 claims description 11
- LJCNRYVRMXRIQR-OLXYHTOASA-L potassium sodium L-tartrate Chemical group [Na+].[K+].[O-]C(=O)[C@H](O)[C@@H](O)C([O-])=O LJCNRYVRMXRIQR-OLXYHTOASA-L 0.000 claims description 8
- 235000011006 sodium potassium tartrate Nutrition 0.000 claims description 8
- 239000001476 sodium potassium tartrate Substances 0.000 claims description 5
- 229940074439 potassium sodium tartrate Drugs 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 5
- 239000013049 sediment Substances 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 107
- 238000001556 precipitation Methods 0.000 description 12
- 238000004458 analytical method Methods 0.000 description 10
- 238000011161 development Methods 0.000 description 10
- 238000011084 recovery Methods 0.000 description 9
- 241000606266 Nardostachys Species 0.000 description 8
- 238000005259 measurement Methods 0.000 description 8
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- 241000251468 Actinopterygii Species 0.000 description 4
- JVMRPSJZNHXORP-UHFFFAOYSA-N ON=O.ON=O.ON=O.N Chemical compound ON=O.ON=O.ON=O.N JVMRPSJZNHXORP-UHFFFAOYSA-N 0.000 description 4
- 239000010842 industrial wastewater Substances 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 229960002523 mercuric chloride Drugs 0.000 description 4
- LWJROJCJINYWOX-UHFFFAOYSA-L mercury dichloride Chemical compound Cl[Hg]Cl LWJROJCJINYWOX-UHFFFAOYSA-L 0.000 description 4
- 230000007935 neutral effect Effects 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 238000004821 distillation Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000003911 water pollution Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 244000088401 Pyrus pyrifolia Species 0.000 description 2
- 235000001630 Pyrus pyrifolia var culta Nutrition 0.000 description 2
- 230000000711 cancerogenic effect Effects 0.000 description 2
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- 239000003183 carcinogenic agent Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
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- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- XKLJHFLUAHKGGU-UHFFFAOYSA-N nitrous amide Chemical compound ON=N XKLJHFLUAHKGGU-UHFFFAOYSA-N 0.000 description 2
- 102000004169 proteins and genes Human genes 0.000 description 2
- 108090000623 proteins and genes Proteins 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- 238000003723 Smelting Methods 0.000 description 1
- VDGMIGHRDCJLMN-UHFFFAOYSA-N [Cu].[Co].[Ni] Chemical compound [Cu].[Co].[Ni] VDGMIGHRDCJLMN-UHFFFAOYSA-N 0.000 description 1
- MMDJDBSEMBIJBB-UHFFFAOYSA-N [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] Chemical compound [O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[NH6+3] MMDJDBSEMBIJBB-UHFFFAOYSA-N 0.000 description 1
- 238000011481 absorbance measurement Methods 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
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- 229910021529 ammonia Inorganic materials 0.000 description 1
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- 150000001875 compounds Chemical class 0.000 description 1
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- 239000011707 mineral Substances 0.000 description 1
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- 238000012544 monitoring process Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 238000005375 photometry Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- BITYAPCSNKJESK-UHFFFAOYSA-N potassiosodium Chemical compound [Na].[K] BITYAPCSNKJESK-UHFFFAOYSA-N 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
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Abstract
The invention discloses a method for determining the content of ammonia nitrogen in wastewater, which comprises the following steps: distilling ammonia nitrogen in the wastewater solution, then absorbing with a boric acid solution, and fixing the volume to obtain an absorption liquid; transferring the absorption solution into a colorimetric tube, and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution; measuring the absorbance of the alkaline colorimetric solution using a spectrophotometer; and calculating the content of ammonia nitrogen in the wastewater solution according to the absorbance of the alkaline colorimetric solution. This application absorbs the ammonia nitrogen back through boric acid solution, transfers the absorption liquid to basicity, then surveys the absorbance of basicity colorimetric solution, avoids producing the phenomenon of sediment among the survey process, makes the testing result more accurate.
Description
Technical Field
The invention relates to the technical field of analysis and detection, in particular to a method for measuring the content of ammonia nitrogen in wastewater.
Background
At present, industrial wastewater often contains a large amount of ammonia nitrogen, and the ammonia nitrogen in a water body is NH3Or
NH4 +The compound ammonia and ammonia nitrogen in the form of ions are the most harmful forms in various types of nitrogen, are the signs of water pollution, and have damage to the water ecological environment in multiple aspects. If the content of ammonia nitrogen exceeds the standard, when nitrite nitrogen in water is too high, the water is combined with protein to form nitrosamine which is a strong carcinogen when drunk. The long-term drinking is extremely harmful to the body. The fish is sensitive to ammonia nitrogen in water, and when the ammonia nitrogen content is high, the fish can die. Therefore, in order to protect the environment and maintain the healthy living environment of people, industrial wastewater generated in the industrial production process needs to be treated to reach the standard before being discharged.
In the process of detecting the content of ammonia nitrogen in wastewater, in the prior art, the ammonia nitrogen is often reacted with a Navier reagent to generate a light red complex, and the concentration of the ammonia nitrogen is calculated by a method for measuring the absorbance of the light red complex.
However, in actual operation, precipitation occurs after the addition of the na's reagent to the solution to be measured, which affects the measurement result and reduces the accuracy of the measurement.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a method for measuring the content of ammonia nitrogen in wastewater, and aims to solve the problem that the detection result is inaccurate due to precipitation generated in the process of detecting the content of ammonia nitrogen in wastewater.
The technical scheme of the invention is as follows:
a method for determining the content of ammonia nitrogen in wastewater comprises the following steps:
distilling ammonia nitrogen in the wastewater solution, then absorbing with a boric acid solution, and fixing the volume to obtain an absorption liquid;
transferring the absorption solution into a colorimetric tube, and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution;
measuring the absorbance of the alkaline colorimetric solution using a spectrophotometer;
and calculating the content of ammonia nitrogen in the wastewater solution according to the absorbance of the alkaline colorimetric solution.
The method for determining the content of ammonia nitrogen in the wastewater comprises the step of absorbing the ammonia nitrogen in the wastewater solution by adopting 50mL of 20g/L boric acid solution.
The method for determining the content of ammonia nitrogen in the wastewater comprises the step of distilling the wastewater solution by adopting an integrated universal distiller.
The method for determining the content of ammonia nitrogen in wastewater comprises the following steps of transferring the absorption liquid into a colorimetric tube, and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution, and specifically comprises the following steps:
transferring 50mL of the absorption solution into a colorimetric tube, and then adding at least 2mL of 1mol/L sodium hydroxide solution to obtain an alkaline colorimetric solution.
The method for determining the content of ammonia nitrogen in the wastewater is characterized in that the pH value of the alkaline colorimetric solution is equal to or more than 9.6.
The method for determining the content of ammonia nitrogen in the wastewater comprises the following steps of, before the step of determining the absorbance of the alkaline colorimetric solution by using a spectrophotometer:
and sequentially adding a masking agent and a Narse reagent into the alkaline colorimetric solution.
The method for determining the content of ammonia nitrogen in the wastewater is characterized in that the masking agent is a potassium sodium tartrate solution.
The method for determining the content of ammonia nitrogen in the wastewater comprises the following steps of sequentially adding a masking agent and a Nashin reagent into the alkaline colorimetric solution:
to the basic colorimetric solution was added 1mL of sodium potassium tartrate solution followed by 1.5mL of na's reagent and developed for at least 15 min.
The method for determining the content of ammonia nitrogen in the wastewater comprises the following steps of using a spectrophotometer to determine the absorbance of the alkaline colorimetric solution:
under the irradiation of light, a cuvette with the caliber of 20mm is used, water is used as a reference, and a spectrophotometer is adopted to measure the absorbance of the alkaline colorimetric solution.
The method for determining the content of ammonia nitrogen in the wastewater is characterized in that the spectrophotometer is irradiated by light with the wavelength of 420 nm.
Compared with the prior art, the embodiment of the invention has the following advantages:
according to the determination method disclosed by the application, after the ammonia nitrogen in the wastewater is absorbed by the boric acid solution, the Nashin reagent is not directly added, but the pH value of the absorption liquid is adjusted to be alkaline, then the absorbance of the alkaline colorimetric solution is determined, the precipitation phenomenon cannot occur in the alkaline environment, the absorbance data determined after the precipitation is eliminated is more accurate, the accurate numerical value of the ammonia nitrogen content in the wastewater solution can be calculated, and the accuracy of detection is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of the method for determining the content of ammonia nitrogen in wastewater according to the invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In recent years, the social economy of China is rapidly developed, and great demands are made on mineral resources, particularly rare earth resources. Along with the development of industries such as petroleum, chemical industry, metallurgy, food, pharmacy and the like and the continuous improvement of the living standard of people, the content of ammonia nitrogen in industrial wastewater and urban domestic wastewater is increased sharply, and the characteristics of more ammonia nitrogen pollution sources, large discharge amount and increased discharge concentration are presented. Under the background, how to select an efficient and economic method to quickly detect the water pollution has become the key point of the research of the water pollution control engineering technology.
At present, industrial wastewater generated in the production process of the smelting industry can be discharged only after being treated to reach GB 25467-emission Standard of pollutants for copper Nickel cobalt industry. The ammonia nitrogen discharged into the water body is decomposed into nitrite nitrogen under the action of microorganisms, and the nitrite nitrogen is continuously decomposed to finally become nitrate nitrogen, so that the self-purification process of the water is completed. However, if the content of ammonia nitrogen exceeds the standard, when nitrite nitrogen in water is too high, the water is combined with protein to form nitrosamine which is a strong carcinogen when being drunk. The long-term drinking is extremely harmful to the body. The fish is sensitive to ammonia nitrogen in water, and when the ammonia nitrogen content is high, the fish can die. Therefore, the accuracy of the measurement result of ammonia nitrogen in the wastewater is significant to the control of the production process. According to the ammonia nitrogen content range, the analysis standard adopted by the inventor is Q/YTGG.XN.J13.01.6-2019 part 6 of environmental monitoring analysis regulation, which is formulated by replacing GB7479-87 Nashin reagent spectrophotometry for measuring ammonia nitrogen in water with reference to HJ 535-2009: ammonia nitrogen determination by Naeser reagent photometry.
In the prior art, a wastewater test solution is pretreated and absorbed, then a Nashin reagent prepared by mercuric chloride is added for color development, and then the absorbance is measured. In actual work, the pH value of the colorimetric solution is adjusted to be neutral according to the rule, and then the strong-alkaline mercuric chloride is added to prepare the NanS reagent, trace mercuric chloride is separated out, so that the colorimetric solution is precipitated, the ammonia nitrogen content measurement result is low due to precipitation, and the accuracy of the detection result is influenced.
Referring to fig. 1, in an embodiment of the present application, a method for determining an ammonia nitrogen content in wastewater is disclosed, wherein the method includes:
s100, distilling ammonia nitrogen in the wastewater solution, then absorbing with a boric acid solution, and fixing the volume to obtain an absorption liquid;
s200, transferring the absorption liquid into a colorimetric tube, and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution;
s300, measuring the absorbance of the alkaline colorimetric solution by using a spectrophotometer;
s400, calculating the ammonia nitrogen content in the wastewater solution according to the absorbance of the alkaline colorimetric solution.
In the determination method disclosed by the application, after ammonia nitrogen in the wastewater is absorbed by the boric acid solution, the sodium hydroxide solution is added into the absorption liquid instead of directly adding the sodium hydroxide solution, the pH value of the solution is adjusted to be alkaline, then the absorbance of the alkaline colorimetric solution is determined, the precipitation phenomenon cannot occur in the alkaline environment, the absorbance data determined after the precipitation is eliminated is more accurate, the accurate numerical value of the ammonia nitrogen content in the wastewater solution can be calculated, and the accuracy of detection is improved.
Specifically, as an implementation manner of this embodiment, it is disclosed that 50mL of a 20g/L boric acid solution is adopted to absorb ammonia nitrogen in the wastewater solution in the S100 step.
Preferably, the wastewater solution is distilled using an integrated universal distiller. The integrated universal distillation instrument has the advantages of high thermal efficiency, long service life, high temperature rising and reducing speed, adjustable heating time and heating power, capability of precisely controlling the temperature in the distillation process and high recovery rate.
Specifically, as another implementation manner of this embodiment, the step S200 is disclosed, and specifically includes:
transferring 50mL of the absorption solution into a colorimetric tube, and then adding at least 2mL of 1mol/L sodium hydroxide solution to obtain an alkaline colorimetric solution.
Preferably, the pH of the basic colorimetric solution is equal to or greater than 9.6 by adding sufficient sodium hydroxide solution. According to the experimental data result, when the pH value of the alkaline colorimetric solution is greater than or equal to 9.6, the chromogenic Navier reagent is added, the measurement result of the standard water quality sample can always meet the standard value given by the certificate, and no precipitation exists.
Specifically, as another implementation manner of this embodiment, before the step S300, the method further includes:
and sequentially adding a masking agent and a Narse reagent into the alkaline colorimetric solution.
The masking agent is added to mask the interfering ions, so that the interfering ions in the solution are prevented from influencing the reaction of the ammonia nitrogen and the Narse reagent, the measured absorbance value is more accurate, and the accuracy of the detection result is improved. Preferably, the masking agent is disclosed as a sodium potassium tartrate solution.
Specifically, as another implementation manner of this embodiment, the step of sequentially adding the masking agent and the nanosecond reagent to the alkaline colorimetric solution is disclosed, and specifically includes:
to the basic colorimetric solution was added 1mL of sodium potassium tartrate solution followed by 1.5mL of na's reagent and developed for at least 15 min.
The potassium-sodium acid solution is added to serve as a masking agent, and then the Nar reagent is heated to react with the ammonia nitrogen to enable the reaction to be complete, so that the ammonia nitrogen in the alkaline colorimetric solution and the Nar reagent are reacted fully to develop color, and the situation that the absorbance value is unstable or smaller than the actual value in the next absorbance measurement process is avoided.
Specifically, as another implementation manner of this embodiment, the step of measuring the absorbance of the alkaline colorimetric solution by using a spectrophotometer is disclosed, which specifically includes:
under the irradiation of light, a cuvette with the caliber of 20mm is used, water is used as a reference, and a spectrophotometer is adopted to measure the absorbance of the alkaline colorimetric solution.
Preferably, the spectrophotometer is disclosed as being illuminated with light having a wavelength of 420 nm.
The following is a further description with reference to specific examples.
Example 1
Drawing a standard working curve and measuring the standard recovery rate
Adding 1.0mL of sodium potassium tartrate solution into 0.00ug, 5.00ug, 10.00ug, 20.00ug, 40.00ug, 60.00ug, 80.00ug and 100.00ug of ammonia nitrogen standards, preparing 1.5mL of Nashi reagent, developing for 15min, irradiating with light with wavelength of 420nm, measuring absorbance value in a cuvette with 20mm aperture by using water as reference, and drawing a standard working curve. The specific plotted characteristic values of the standard working curve are as follows: YI ═ 0.0082 x-0.006; r20.9999; blank absorbance value: 0.026.
the standard recovery at the middle point of the curve was then determined from the plotted standard operating curve, and the results are shown in table 1.
TABLE 1
Example 2
In the prior art, the color development of a standard water quality sample is measured as follows:
and distilling the standard water quality sample, absorbing by boric acid solution and fixing the volume. Transferring into a colorimetric tube, dropwise adding 2 drops of 1mol/L sodium hydroxide, adjusting the pH to 7.75 according to the requirements of the regulations, adding a Nassner reagent for color development, and then measuring. The analysis results are shown in Table 2.
TABLE 2
Therefore, the result of the absorbance value actually detected in the prior art is usually smaller than the standard value, and the trace amount of precipitate is observed in the determination process after the addition of the Navier reagent, so that the ammonia nitrogen does not completely react with the Navier reagent, and the finally determined absorbance value is small and inaccurate.
Example 3
By adopting a 50ug ammonia nitrogen standard, distilling the wastewater solution, absorbing 50mL boric acid with the concentration of 20g/L, transferring 50mL absorption liquid into a colorimetric tube, adding 1mol/L sodium hydroxide with different amounts to adjust the pH value, adding a Nashin reagent for color development, and determining results shown in Table 3.
TABLE 3
| 1mol/L sodium hydroxide adding amount | Without adding | 2 drops of the Chinese medicinal composition | 0.5mL | 1mL | 2mL | 3mL | 4mL |
| 50ug ammonia nitrogen standard absorbance value | 0.024 | 0.025 | 0.262 | 0.377 | 0.416 | 0.415 | 0.416 |
From the above, when the addition amount of 1mol/L sodium hydroxide solution is 2mL, the standard absorbance value of 50ug ammonia nitrogen is the largest, and the standard recovery rate is as follows: 96.58 percent and meets the requirement of 95 to 105 percent of HJ535-2009 standard recovery rate.
Example 4
The color development pH of the alkaline colorimetric solution was determined according to example 3 using a Hash HQ40d ion activity meter with 1mol/L sodium hydroxide addition. The measurement results are shown in Table 4.
TABLE 4
Therefore, when the addition of 1mol/L of sodium hydroxide is 2mL, the standard absorbance value of 50ug of ammonia nitrogen reaches the maximum value, so that when the standard recovery rate meets the standard requirement, the color development pH value of the alkaline colorimetric solution is 9.64.
Example 5
The wastewater solution was pretreated and adjusted to pH9.6, and then subjected to color development measurement. The method comprises the following specific steps:
distilling ammonia nitrogen in the wastewater solution, then absorbing by using 50mL boric acid solution with the concentration of 20g/L, and fixing the volume to obtain absorption liquid;
transferring 50mL of the absorption solution into a colorimetric tube, then adding 0.5mL of sodium hydroxide solution with the concentration of 4mol/L, and adjusting the pH value to 9.6 to obtain an alkaline colorimetric solution;
adding 1mL of potassium sodium tartrate solution into the alkaline colorimetric solution, then adding 1.5mL of a Nashin reagent, developing for at least 15min, and measuring the absorbance of the alkaline colorimetric solution by using a spectrophotometer;
and calculating the content of ammonia nitrogen in the wastewater solution according to the absorbance of the alkaline colorimetric solution.
The analysis results are shown in Table 5.
TABLE 5
Combining example 4 with the above results, it can be concluded that: and (3) adjusting the colorimetric solution to be alkaline, adding a chromogenic Nashin reagent after the pH value of the colorimetric solution is not less than 9.6, and enabling the measurement result of the standard water quality sample to meet the standard value given by the certificate. That is, this embodiment has thoroughly eliminated the phenomenon that the colorimetric solution appears the deposit by adding the nano-grade reagent of strong alkaline mercuric chloride preparation after adjusting colorimetric solution pH value to alkaline, has guaranteed the accuracy of ammonia nitrogen analysis result.
Example 6
To further verify the experimental results of the examples of the present application, the present example performed chromogenic assay by adding different na's reagents to neutral colorimetric solution and alkaline colorimetric solution, respectively, and the results were compared.
(1) After the colorimetric solution was adjusted to neutral according to the method in the above example, different Nardostachys reagents (group I: preparation of Nardostachys reagent; group II: purchased domestic Nardostachys reagent; group III: purchased imported Nardostachys reagent) were added, and the analysis results are shown in Table 6.
TABLE 6
Therefore, different nano-reagents are added into the neutral colorimetric solution for color development determination, and the analysis results have great difference. The samples where precipitation occurred were analyzed to be lower.
(2) After the colorimetric solution was made alkaline according to the method in the above example, different Nardostachys reagents (group I: preparation of Nardostachys reagent; group II: purchased domestic Nardostachys reagent; group III: purchased imported Nardostachys reagent) were added, and the analysis results are shown in Table 7.
TABLE 7
Therefore, the colorimetric solution is adjusted to be alkaline (pH9.6), and then the chromogenic reagent is added, so that no precipitation occurs, different Nashi reagents are used for developing color, the analysis result is stable, and the relative range difference is less than or equal to 12%. (the repeatability limit is 0.028mg/L and the reproducibility limit is 0.075mg/L for the standard solution with the ammonia nitrogen concentration of 1.21mg/L, and the repeatability limit is 0.024mg/L and the reproducibility limit is 0.066mg/L for the standard solution with the ammonia nitrogen concentration of 1.47 mg/L).
Example 7
Adding ammonia nitrogen standard into recycled water 2020-8-20 of a production sample, adjusting the colorimetric solution to be alkaline (pH9.6) after distillation and boric acid absorption, adding a prepared Nashinese reagent for color development, and measuring the standard recovery rate, wherein the result is shown in Table 8.
TABLE 8
Therefore, the standard recovery rate meets the requirements of HJ535-2009 and the standard recovery rate is 95% -105%.
In summary, the application discloses a method for determining ammonia nitrogen content in wastewater, wherein the method comprises the following steps:
s100, distilling ammonia nitrogen in the wastewater solution, then absorbing with a boric acid solution, and fixing the volume to obtain an absorption liquid;
s200, transferring the absorption liquid into a colorimetric tube, and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution;
s300, measuring the absorbance of the alkaline colorimetric solution by using a spectrophotometer;
s400, calculating the ammonia nitrogen content in the wastewater solution according to the absorbance of the alkaline colorimetric solution. In the determination method disclosed by the application, after ammonia nitrogen in the wastewater is absorbed by the boric acid solution, the sodium hydroxide solution is added into the absorption liquid instead of directly adding the sodium hydroxide solution, the pH value of the solution is adjusted to be alkaline, then the absorbance of the alkaline colorimetric solution is determined, the precipitation phenomenon cannot occur in the alkaline environment, the absorbance data determined after the precipitation is eliminated is more accurate, the accurate numerical value of the ammonia nitrogen content in the wastewater solution can be calculated, and the accuracy of detection is improved.
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.
It will be understood that the invention is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A method for determining the content of ammonia nitrogen in wastewater is characterized by comprising the following steps:
distilling ammonia nitrogen in the wastewater solution, then absorbing with a boric acid solution, and fixing the volume to obtain an absorption liquid;
transferring the absorption solution into a colorimetric tube, and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution;
measuring the absorbance of the alkaline colorimetric solution using a spectrophotometer;
and calculating the content of ammonia nitrogen in the wastewater solution according to the absorbance of the alkaline colorimetric solution.
2. The method for determining the content of ammonia nitrogen in wastewater according to claim 1, characterized in that 50mL of 20g/L boric acid solution is used for absorbing ammonia nitrogen in the wastewater solution.
3. The method for determining the content of ammonia nitrogen in wastewater according to claim 1, characterized in that the wastewater solution is distilled by an integrated universal distiller.
4. The method for determining the content of ammonia nitrogen in wastewater according to claim 1, wherein the step of transferring the absorption solution to a colorimetric tube and then adding a sodium hydroxide solution to obtain an alkaline colorimetric solution specifically comprises:
transferring 50mL of the absorption solution into a colorimetric tube, and then adding at least 2mL of 1mol/L sodium hydroxide solution to obtain an alkaline colorimetric solution.
5. The method for determining the content of ammonia nitrogen in wastewater according to claim 4, wherein the pH value of the alkaline colorimetric solution is equal to or greater than 9.6.
6. The method for determining the content of ammonia nitrogen in wastewater according to claim 1, wherein before the step of measuring the absorbance of the alkaline colorimetric solution by using a spectrophotometer, the method further comprises the following steps:
and sequentially adding a masking agent and a Narse reagent into the alkaline colorimetric solution.
7. The method for determining the content of ammonia nitrogen in wastewater according to claim 6, characterized in that the masking agent is a potassium sodium tartrate solution.
8. The method for determining the content of ammonia nitrogen in wastewater according to claim 6, wherein the step of sequentially adding a masking agent and a Narse reagent into the alkaline colorimetric solution specifically comprises:
to the basic colorimetric solution was added 1mL of sodium potassium tartrate solution followed by 1.5mL of na's reagent and developed for at least 15 min.
9. The method for determining the ammonia nitrogen content in wastewater according to claim 8, wherein the step of measuring the absorbance of the alkaline colorimetric solution using a spectrophotometer comprises:
under the irradiation of light, a cuvette with the caliber of 20mm is used, water is used as a reference, and a spectrophotometer is adopted to measure the absorbance of the alkaline colorimetric solution.
10. The method for determining the content of ammonia nitrogen in wastewater according to claim 1, wherein the spectrophotometer irradiates light with a wavelength of 420 nm.
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