CN110849834A - Reagent and method for determining chemical oxygen demand of sewage by rapid digestion and colorimetric determination - Google Patents
Reagent and method for determining chemical oxygen demand of sewage by rapid digestion and colorimetric determination Download PDFInfo
- Publication number
- CN110849834A CN110849834A CN201911191004.1A CN201911191004A CN110849834A CN 110849834 A CN110849834 A CN 110849834A CN 201911191004 A CN201911191004 A CN 201911191004A CN 110849834 A CN110849834 A CN 110849834A
- Authority
- CN
- China
- Prior art keywords
- sulfuric acid
- reagent
- oxygen demand
- chemical oxygen
- volume ratio
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/44—Sample treatment involving radiation, e.g. heat
Abstract
The invention provides a reagent and a method for determining chemical oxygen demand of sewage by fast digestion colorimetry. The method includes digesting a water sample using the reagent. The method can be used for determination by using a common spectrophotometer in a laboratory, a matched spectrophotometer is not needed, the detection cost is reduced, the method is simple to operate, the digestion time is short, dozens of water samples can be digested simultaneously, and the method is suitable for batch detection of the water samples. The experimental result shows that the detection limit of the method is 4.52mg/L, the oxidation rate of the organic matter is more than or equal to 99.0 percent, and the relative error of the chemical oxygen demand measured by the method is less than or equal to 5 percent compared with the result measured by the Hash method.
Description
Technical Field
The invention relates to the field of water quality analysis, in particular to a reagent and a method for determining sewage chemical oxygen demand by rapid digestion colorimetry.
Background
Along with the increasing attention of people on environmental protection, governments in various places continuously improve the sewage discharge standard of sewage treatment enterprises. In order to ensure that the received sewage can be discharged after reaching the standard under the existing process conditions, sewage treatment enterprises need to sample various types of received sewage frequently and detect the content of pollution factors. The chemical oxygen demand of the sewage is one of the main monitoring indexes of the environmental water quality standard, which reflects the degree of pollution of a water sample by reducing substances, wherein the reducing substances in the water comprise organic matters, sulfides, nitrites, ferrous salts and the like, the organic matters are main pollutants, and therefore, the chemical oxygen demand is also a comprehensive index for measuring the content of the organic matters in the sewage. The chemical oxygen demand of the water quality is grasped in time and used for guiding the process production operation, and the method has very important significance for sewage treatment enterprises.
At present, the national standard method of dichromate and the closed digestion colorimetric method of Hash company are commonly adopted in laboratories to determine the chemical oxygen demand in sewage. The dichromate method has good reproducibility, but the operation steps are complicated, the reagent dosage is large, the digestion time is long, and the method is not suitable for detecting samples in batches. The method for determining the chemical oxygen demand by closed digestion colorimetry established by Hash company is a detection method approved by the United states environmental protection agency. However, the chemical oxygen demand reagent of the hash company and the matched digester and spectrophotometer are expensive, which results in high detection cost. In addition, the digestion time of the Hash method is 2 hours, and the digestion time is long, so that the requirement of quickness cannot be met.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a reagent and a method for determining the chemical oxygen demand of sewage by fast digestion and colorimetric determination.
The invention aims to provide a reagent for rapidly digesting and colorimetrically measuring the chemical oxygen demand of sewage, which comprises a catalyst and a composite oxidant, wherein the catalyst comprises silver sulfate and concentrated sulfuric acid, and the composite oxidant comprises potassium dichromate, ammonium metavanadate, ammonium molybdate, potassium sulfate, mercury sulfate and dilute sulfuric acid.
According to the invention, potassium dichromate, ammonium metavanadate, ammonium molybdate, potassium sulfate and mercury sulfate are dissolved in dilute sulfuric acid to prepare a composite oxidant to replace a tubular reagent of a Hash company, so that the detection cost is greatly reduced, wherein the digestion speed is accelerated by the combined action of the ammonium metavanadate, the ammonium molybdate and the potassium sulfate, the digestion time is shortened to 3-5 min from 2h of a Hash method, the detection efficiency is greatly improved, and the method is favorable for popularization and utilization.
Furthermore, the mass-volume ratio of the silver sulfate to the concentrated sulfuric acid in the catalyst is 2.5-5.0 g:500 mL.
Further, the mass volume ratio of potassium dichromate, ammonium metavanadate, ammonium molybdate, potassium sulfate, mercury sulfate and dilute sulfuric acid in the composite oxidant is 1.5-3 g: 2-3.5 g: 2-4 g: 4-6 g: 2.5-4 g: 130-150 ml, wherein the dilute sulfuric acid is composed of pure water and concentrated sulfuric acid according to the volume ratio of 100: 30-50.
Further, the preparation of the composite oxidant comprises the following steps: the potassium dichromate, the ammonium metavanadate, the ammonium molybdate, the potassium sulfate and the mercury sulfate are respectively weighed according to the proportion and are placed in a beaker, pure water is added, then concentrated sulfuric acid with a certain volume is slowly added, and the mixture is stirred while being added until the mixture is completely dissolved.
The invention also provides a method for determining the chemical oxygen demand of the sewage by rapid digestion colorimetry, which comprises the step of digesting a water sample by using any one of the above reagents.
Specifically, the composite oxidant and the catalyst are added into a water sample for closed digestion, wherein the digestion temperature is 150-165 ℃, and the digestion time is 3-5 min.
Further, the volume ratio of the composite oxidant to the water sample is 1 (2-3); the volume ratio of the catalyst to the water sample is (1-2) to 1.
Further, the method further comprises: and cooling after digestion, adding pure water according to the volume ratio of 1: 1-1: 2 of the water sample to the pure water, shaking up, cooling, and then measuring the chemical oxygen demand of the water sample by using a 3cm cuvette at 610nm by using a common spectrophotometer.
The method is suitable for sewage with the chemical oxygen demand of 5-1000 mg/L.
The method can be used for determination by using a common spectrophotometer in a laboratory, a matched spectrophotometer is not needed, the detection cost is reduced, the method is simple to operate, the digestion time is short, dozens of water samples can be digested simultaneously, and the method is suitable for batch detection of the water samples. The experimental result shows that the detection limit of the method is 4.52mg/L, the oxidation rate of the organic matter is more than or equal to 99.0 percent, and the relative error of the chemical oxygen demand measured by the method is less than or equal to 5 percent compared with the result measured by the Hash method.
Drawings
FIG. 1 is a COD standard curve chart in the example of the present invention.
Detailed Description
The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention. The examples do not show the specific techniques or conditions, according to the technical or conditions described in the literature in the field, or according to the product specifications. The reagents or instruments used are conventional products available from regular distributors, not indicated by the manufacturer.
Example 1
The embodiment provides a reagent for determining chemical oxygen demand of sewage by fast digestion and colorimetric method, which comprises a catalyst and a composite oxidant, wherein the catalyst is prepared from 500ml of concentrated H2SO4And 2.5g Ag2SO4Preparing; the composite oxidant consists of 2g of K2Cr2O73g NH4VO33g (NH)4)2MoO45g of K2SO43g HgSO4And 135ml of dilute H2SO4(pure water 100ml added with 35ml concentrated sulfuric acid).
This example also provides a method for chemical oxygen demand measurement of wastewater using the above reagent, and the measurement results are analyzed as follows:
(1) pharmaceutical formulation
COD standard solution: 0.5951g of potassium hydrogen phthalate (reference reagent) dried at 105 ℃ for 2h is weighed, dissolved in primary pure water, diluted to 1000mL and mixed evenly. The theoretical COD value of this standard solution was 700 mg/L.
Composite oxidant: respectively weighing 2g of potassium dichromate, 3g of ammonium metavanadate, 3g of ammonium molybdate, 5g of potassium sulfate and 3g of mercury sulfate, putting the potassium dichromate, the ammonium metavanadate, the ammonium molybdate, the potassium sulfate and the mercury sulfate in a beaker, adding 100mL of water, weighing 35mL of concentrated sulfuric acid, slowly adding the concentrated sulfuric acid into the beaker while stirring until the concentrated sulfuric acid is completely dissolved, cooling, and pouring the solution into a brown reagent bottle for storage.
Silver sulfate-sulfuric acid solution: 2.5g of silver sulfate was added to 500mL of concentrated sulfuric acid, and the mixture was dissolved and shaken up for use.
(2) Drawing a COD standard curve
0.00mL, 0.10mL, 0.30mL, 0.70mL, 1.00mL, 1.50mL, 2.00mL of the COD standard solution were taken out of the digestion tube, and pure water was added to make up to 2.00mL of the COD standard solution. The theoretical COD concentrations were 0.00mg/L, 35.0mg/L, 105mg/L, 245mg/L, 350mg/L, 525mg/L, 700mg/L, respectively. 1.00mL of a composite oxidizing agent and 3.00mL of a silver sulfate-sulfuric acid solution were added, the caps of the digestion tubes were closed, the mixture was shaken up and heated in a 165 ℃ digestion vessel for 5 minutes, after cooling down, 3.00mL of pure water was added, and the mixture was shaken up again, and after cooling down, absorbance was measured at 610nm in a 3cm cuvette, and the results are shown in Table 1.
TABLE 1 Absorbance for different COD concentrations
The COD standard curve is drawn, the result is shown in figure 1, and the linear correlation coefficient of the COD standard curve reaches 0.9999, which completely meets the requirement.
(3) COD measurement results
A. COD measurement result of standard solution
Preparing standard solutions with different concentrations by using potassium hydrogen phthalate to measure absorbance, obtaining COD measurement results according to the measured absorbance and a COD standard curve, and respectively carrying out 6 times of parallel measurement, wherein the measurement results are shown in Table 2.
TABLE 2 COD measurement results of the standard solutions
As can be seen from Table 2, the relative error and the relative standard deviation are less than 2% when the standard solution concentration is between 50.0mg/L and 700 mg/L.
B. COD determination results of different sewage samples
Actual sewage samples with different concentrations and different properties are collected, fully and uniformly mixed, and then the actual sewage samples are respectively measured by a Hash method and the method of the embodiment, and the measurement results are shown in Table 3.
TABLE 3 COD determination results of different wastewater samples
As can be seen from Table 3, for the sewage samples with different concentrations, the average value is compared with the Hash method after 6 times of parallel measurement, and the relative error and the relative standard deviation are both less than 5%.
(4) Estimation of Detection Limit (DL)
The blank absorbances of 11 samples of pure water were measured in the same manner as in the measurement of the sample water, except that the sample was replaced with pure water for the experiment, and the results are shown in Table 4.
Table 4 blank absorbance measurement results for samples
Then, the detection limit of the method of the present embodiment is calculated as DL-3S according to the calculation formulawb/A＝3×0.00098/0.00065＝4.52mg/L，
Note: swbThe standard deviation of the blank absorbance, A is the slope of the COD standard curve.
Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.
Claims (10)
1. The reagent for determining the chemical oxygen demand of sewage by fast digestion colorimetry is characterized by comprising a catalyst and a composite oxidant, wherein the catalyst contains silver sulfate and concentrated sulfuric acid, and the composite oxidant contains potassium dichromate, ammonium metavanadate, ammonium molybdate, potassium sulfate, mercury sulfate and dilute sulfuric acid.
2. The reagent according to claim 1, wherein the mass-to-volume ratio of the silver sulfate to the concentrated sulfuric acid in the catalyst is 2.5-5.0 g:500 mL.
3. The reagent according to claim 1 or 2, wherein the mass volume ratio of potassium dichromate, ammonium metavanadate, ammonium molybdate, potassium sulfate, mercury sulfate and dilute sulfuric acid in the composite oxidant is 1.5-3 g: 2-3.5 g: 2-4 g: 4-6 g: 2.5-4 g: 130-150 ml, and the dilute sulfuric acid is composed of pure water and concentrated sulfuric acid in a volume ratio of 100: 30-50.
4. The reagent according to claim 3, wherein the composite oxidant consists of potassium dichromate, ammonium metavanadate, ammonium molybdate, potassium sulfate, mercury sulfate and dilute sulfuric acid in a mass-to-volume ratio of 2g:3g:3g:5g:3g:135ml, wherein the dilute sulfuric acid consists of pure water and concentrated sulfuric acid in a volume ratio of 100: 35.
5. The reagent of claim 4, wherein the preparation of the complex oxidant comprises: the potassium dichromate, the ammonium metavanadate, the ammonium molybdate, the potassium sulfate and the mercury sulfate are respectively weighed according to the proportion and are placed in a beaker, pure water is added, then concentrated sulfuric acid is slowly added, and stirring is carried out while adding until the concentrated sulfuric acid is completely dissolved.
6. A method for determining chemical oxygen demand of sewage through rapid digestion colorimetry, which is characterized by comprising the step of digesting a water sample by using the reagent according to any one of claims 1 to 5.
7. The method according to claim 6, characterized by adding the composite oxidant and the catalyst into a water sample, and carrying out closed digestion at the temperature of 150-165 ℃ for 3-5 min.
8. The method according to claim 7, wherein the volume ratio of the composite oxidant to the water sample is 1 (2-3); the volume ratio of the catalyst to the water sample is (1-2) to 1.
9. The method according to claim 7 or 8, characterized in that the method further comprises: and cooling after digestion, adding pure water according to the volume ratio of 1: 1-1: 2 of the water sample to the pure water, shaking up, cooling, and then measuring the absorbance of the water sample by using a 3cm cuvette at 610nm by using a common spectrophotometer so as to calculate the chemical oxygen demand.
10. The method according to claim 6, wherein the method is suitable for sewage with the chemical oxygen demand of 5-1000 mg/L.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911191004.1A CN110849834A (en) | 2019-11-28 | 2019-11-28 | Reagent and method for determining chemical oxygen demand of sewage by rapid digestion and colorimetric determination |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911191004.1A CN110849834A (en) | 2019-11-28 | 2019-11-28 | Reagent and method for determining chemical oxygen demand of sewage by rapid digestion and colorimetric determination |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110849834A true CN110849834A (en) | 2020-02-28 |
Family
ID=69606276
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911191004.1A Pending CN110849834A (en) | 2019-11-28 | 2019-11-28 | Reagent and method for determining chemical oxygen demand of sewage by rapid digestion and colorimetric determination |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110849834A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114199797A (en) * | 2021-11-12 | 2022-03-18 | 葛洲坝水务温岭有限公司 | Method for rapidly measuring low-range COD |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5556787A (en) * | 1995-06-07 | 1996-09-17 | Hach Company | Manganese III method for chemical oxygen demand analysis |
| CN101713739A (en) * | 2008-12-05 | 2010-05-26 | 江苏工业学院 | Reagent and method for determining chemical oxygen demand of high-chloride wastewater |
| CN101839901A (en) * | 2009-03-17 | 2010-09-22 | 程俊彪 | Digestion solution formula for fast determining chemical oxygen demand |
| CN105259296A (en) * | 2015-10-12 | 2016-01-20 | 河南广电计量检测有限公司 | Catalyst applied to chemical oxygen demand testing and chemical oxygen demand testing method |
| CN110252339A (en) * | 2019-07-30 | 2019-09-20 | 宜兴国际环保城科技发展有限公司 | A kind of composite catalyst for the processing of the biochemical waste water of difficulty containing antibiotic |
-
2019
- 2019-11-28 CN CN201911191004.1A patent/CN110849834A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5556787A (en) * | 1995-06-07 | 1996-09-17 | Hach Company | Manganese III method for chemical oxygen demand analysis |
| CN101713739A (en) * | 2008-12-05 | 2010-05-26 | 江苏工业学院 | Reagent and method for determining chemical oxygen demand of high-chloride wastewater |
| CN101839901A (en) * | 2009-03-17 | 2010-09-22 | 程俊彪 | Digestion solution formula for fast determining chemical oxygen demand |
| CN105259296A (en) * | 2015-10-12 | 2016-01-20 | 河南广电计量检测有限公司 | Catalyst applied to chemical oxygen demand testing and chemical oxygen demand testing method |
| CN110252339A (en) * | 2019-07-30 | 2019-09-20 | 宜兴国际环保城科技发展有限公司 | A kind of composite catalyst for the processing of the biochemical waste water of difficulty containing antibiotic |
Non-Patent Citations (3)
| Title |
|---|
| 张永利 等: "CWAO处理亚加蓝水溶液中催化剂的筛选", 《工业安全与环保》 * |
| 杨保祥 等: "《钒基材料制造》", 31 March 2014 * |
| 马荣华: "《中级无机化学》", 31 January 2012 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114199797A (en) * | 2021-11-12 | 2022-03-18 | 葛洲坝水务温岭有限公司 | Method for rapidly measuring low-range COD |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101713739B (en) | Reagent and method for determining chemical oxygen demand of high-chloride wastewater | |
| CN109187395A (en) | The measuring method of total phosphorus content in a kind of detergent | |
| CN103278501B (en) | COD quick detection solution, test box and determination method | |
| CN102590442B (en) | Determination method for organic carbon | |
| CN109085049A (en) | COD detection method in a kind of sewage and recycled water | |
| CN110987918A (en) | Detection reagent and rapid detection method for total nitrogen in water | |
| CN102279183A (en) | Method of detecting COD in high chlorine water with chloride oxygen demand calibration curve-sealed digestion method | |
| CN101839901A (en) | Digestion solution formula for fast determining chemical oxygen demand | |
| AU2020227024A1 (en) | Method for detecting iodine concentration in water samples | |
| CN110849834A (en) | Reagent and method for determining chemical oxygen demand of sewage by rapid digestion and colorimetric determination | |
| CN101539526A (en) | Method for preparing prefabricated reagent for fast measuring COD in water body and application thereof | |
| CN112255225B (en) | Method for testing COD (chemical oxygen demand) of organic matters in waste hydrochloric acid containing iron | |
| CN108169225A (en) | A kind of analytical reagent and its preparation method of COD quick analytic instruments | |
| CN113655012B (en) | High COD wastewater total nitrogen testing method | |
| CN108776125B (en) | Sample pretreatment reagent and method in process of measuring arsenic in urine | |
| CN117825646A (en) | Mixed reagent for COD detection, COD detection reagent tube and COD detection method | |
| CN110672786A (en) | Method for rapidly detecting COD (chemical oxygen demand) in industrial wastewater | |
| CN108776110A (en) | A method of utilizing the COD in the Microwave Digestion detection sewage of silver-free catalyst | |
| CN110426390B (en) | Method for detecting benzoyl peroxide in flour | |
| CN113758770A (en) | Method for rapidly determining COD content in chlorine-containing wastewater | |
| CN115508501A (en) | Method for detecting chemical oxygen demand in industrial wastewater | |
| CN113433291B (en) | Digestion method and determination method of total nitrogen, phosphorus and potassium in soil | |
| CN116990443B (en) | Accurate detection method for COD in high-chlorine low-COD water sample | |
| CN114199798A (en) | Method for rapidly measuring high-range COD | |
| CN109211892B (en) | Method for detecting content of residual EDTA in lithium fluoride |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200228 |