CN104655790A - Accurate, energy-saving and consumption-reduction method for measuring COD (chemical oxygen demand) - Google Patents
Accurate, energy-saving and consumption-reduction method for measuring COD (chemical oxygen demand) Download PDFInfo
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- CN104655790A CN104655790A CN201510036812.6A CN201510036812A CN104655790A CN 104655790 A CN104655790 A CN 104655790A CN 201510036812 A CN201510036812 A CN 201510036812A CN 104655790 A CN104655790 A CN 104655790A
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Abstract
The invention relates to an accurate, energy-saving and consumption-reduction method for measuring COD (chemical oxygen demand). The method comprises the following steps: preparing potassium dichromate standard solution with the concentration of 0.25mol/L; preparing ferroin indicator solution; preparing ammonium ferrous sulfate solution; preparing sulfuric acid-silver sulfate solution; calibrating the ammonium ferrous sulfate solution, namely, drawing 1mL of potassium dichromate standard solution, adding with water for dilution until reaching 20mL, adding with 3mL of concentrated sulfuric acid, adding with one drop of ferroin indicator solution, placing the ammonium ferrous sulfate solution into a seat type micro burette for titration; weighing 0.04g of mercury sulfate, adding into a HACH transparent threaded pipe, adding with 2mL of water sample, adding with 1mL of potassium dichromate standard solution and 3mL of sulfuric acid-silver sulfate solution simultaneously and placing into a HACH digestion apparatus; performing titration experiment, namely, cooling the solution in the HACH transparent threaded pipe to be at room temperature, transferring the solution into a 50mL conical flask and diluting to reach 20mL with deionized water, adding with one drop of ferroin indicator solution, and titrating with the seat type micro burette, therefore, the COD measurement can be finished. The method is accurate, convenient, safe and environmentally friendly.
Description
Technical field
The present invention relates to a kind of accurately energy-saving and cost-reducing method measuring COD, belong to water quality monitoring method in sewage treatment area.
Background technology
At present, traditional heating reflux method of often adopting of COD (referring to chemical oxygen demand (COD) chemical oxygen demand) detection method and HACH COD method.Wherein, the former device volume is comparatively large, and reagent dosage is large, and cost is high, poor stability in Specimen eliminating process, has certain limitation to Simultaneously test many groups water sample.Need to buy special HACH reagent and HACH tintmeter in the latter's monitoring, expensive, and the waste of HACH color comparison tube single use is serious, substitute reagent if use and replace special HACH reagent, in colorimetric measurement, the transparent threaded line pipe of HACH easily weares and teares, and will directly affect the accuracy of measurement result.
As shown in the above, the conventional COD detection method adopted at present all has certain defect, is therefore necessary to design a kind of accurately energy-saving and cost-reducing method measuring COD, to overcome above-mentioned defect.
Summary of the invention
The object of the invention is to the defect overcoming prior art, provide a kind of accurately energy-saving and cost-reducing method measuring COD of accurate, convenient, safety and environmental protection.
The present invention is achieved in that
The invention provides a kind of accurately energy-saving and cost-reducing method measuring COD, comprise the following steps: step one: compound concentration is the potassium dichromate standard solution of 0.25mo1/L; Step 2: preparation ferroin indicator solution, is dissolved in phenanthroline and ferrous sulphate in deionized water, and dilutes; Step 3: preparation l ferrous ammonium sulfate solution; Step 4: the sulfuric acid-silver sulfate solution of preparation 1%, adds 5g silver sulfate in the 500mL concentrated sulphuric acid; Step 5: the l ferrous ammonium sulfate solution in step 3 is demarcated, accurate absorption 1mL potassium dichromate standard solution is in 50mL conical flask, be diluted with water to 20mL, slowly add the 3mL concentrated sulphuric acid, shake up, after cooling, add 1 ferroin indicator, l ferrous ammonium sulfate solution is placed in A seating microburette and carries out titration, record titration volumes is V
0, the concentration of l ferrous ammonium sulfate solution is C=0.25 × 1/V
0; Step 6: carry out clearing up experiment, gets the transparent threaded line pipe of HACH, is weighed into 0.04g mercuric sulfate, add 2mL water sample, record V
water sample, add the potassium dichromate standard solution of 1mL step one preparation and the sulfuric acid-silver sulfate solution of 3mL step 4 preparation simultaneously, more transparent for HACH threaded line pipe put into HACH counteract appearance, at 150 DEG C, clear up 2 hours; Step 7: clear up after experiment terminates, carry out titration experiments, solution in transparent for HACH threaded line pipe is cooled to room temperature, deionized water is adopted to be transferred to by solution in 50mL conical flask and to be diluted to 20mL, then the ferroin indicator solution of 1 step 2 preparation is added, utilize the A seating microburette that l ferrous ammonium sulfate solution is housed to carry out titration, respectively V is designated as to actual measurement sample and blank titration volume
1and V
blank, finally according to formula COD=(V
blank-V
1) × C × 8 × 1000/V
water sample, the concrete numerical value of COD can be calculated.
Further, the process for preparation of described potassium dichromate standard solution is: take and be dissolved in deionized water at 120 DEG C of oven dry benchmark of 2 hours or high-quality pure potassium dichromate 12.258g in advance, move into 1000mL volumetric flask, be diluted to graticule, then shake up.
Further, the process for preparation of described ferroin indicator solution is: take 1.485g phenanthroline and 0.695g ferrous sulphate is dissolved in deionized water, is diluted to 100mL.
Further, described ferroin indicator solution is stored in brown bottle.
Further, the process for preparation of described l ferrous ammonium sulfate solution is: take 39.5g iron ammonium sulfate and be dissolved in deionized water, slowly add the 20mL concentrated sulphuric acid while stirring, moves in 1000mL volumetric flask, add and be diluted to graticule, and shake up after cooling.
Further, the precision of described A seating microburette is 0.01mL.
Further, the model of the transparent threaded line pipe of described HACH is 16mm × 100mm.
The present invention has following beneficial effect:
The method of described accurately energy-saving and cost-reducing mensuration COD is compared with traditional COD method of testing, and sampling amount and digestion solution equivalent reduce 90%, and waste liquid amount decreases 90%, electricity charge reduction 70%; Compared with HACH COD method, the transparent threaded line pipe of HACH can be repeatedly used, exempt transducer wall ' s abrasion situation to the impact of measurement result, reduce testing cost and ensure that result has higher accuracy rate.The method is accurate, convenient, safety and environmental protection.
Embodiment
Be clearly and completely described the technical scheme in the embodiment of the present invention below, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, other embodiments all that those of ordinary skill in the art obtain under the prerequisite not making creative work, all belong to the scope of protection of the invention.
The embodiment of the present invention provides a kind of accurately energy-saving and cost-reducing method measuring COD (chemical oxygen demand (COD)), comprises the following steps:
Step one: compound concentration is the potassium dichromate standard solution of 0.25mo1/L, the process for preparation of described potassium dichromate standard solution is: take and be dissolved in deionized water at 120 DEG C of oven dry benchmark of 2 hours or high-quality pure potassium dichromate 12.258g in advance, move into 1000mL volumetric flask, be diluted to graticule, then shake up.
Step 2: preparation ferroin indicator solution, by phenanthroline (C
12h
8n
2h
2and ferrous sulphate (FeSO O)
47H
2o) be dissolved in deionized water, and dilute.The concrete process for preparation of described ferroin indicator solution is: take 1.485g phenanthroline and 0.695g ferrous sulphate is dissolved in deionized water, is diluted to 100mL.Wherein, because ferroin is shown in that light easily decomposes, described ferroin indicator solution should be stored in brown bottle.
Step 3: preparation l ferrous ammonium sulfate solution, the process for preparation of described l ferrous ammonium sulfate solution is: take 39.5g iron ammonium sulfate and be dissolved in deionized water, slowly add the 20mL concentrated sulphuric acid while stirring, moves in 1000mL volumetric flask after cooling, add and be diluted to graticule, and shake up.Before use, demarcate with potassium dichromate standard solution.
Step 4: the sulfuric acid-silver sulfate solution of preparation 1%, adds 5g silver sulfate in the 500mL concentrated sulphuric acid, places l ~ 2d, and shake frequently makes it dissolve.
Step 5: the l ferrous ammonium sulfate solution in step 3 is demarcated, accurate absorption 1mL potassium dichromate standard solution is in 50mL conical flask, be diluted with water to 20mL, slowly add the 3mL concentrated sulphuric acid, shake up, after cooling, add 1 ferroin indicator, l ferrous ammonium sulfate solution is placed in A seating microburette and carries out titration, record titration volumes is V
0, the concentration of l ferrous ammonium sulfate solution is C=0.25 × 1/V
0.Wherein, the precision of described A seating microburette is 0.01mL.
Step 6: carry out clearing up experiment, gets the transparent threaded line pipe of HACH, and the model of the transparent threaded line pipe of described HACH is 16mm × 100mm, is accurately weighed into 0.04g mercuric sulfate, adds 2mL water sample, record V
water sample, add the potassium dichromate standard solution of 1mL step one preparation and the sulfuric acid-silver sulfate solution of 3mL step 4 preparation simultaneously, tighten the pipe lid of the transparent threaded line pipe of HACH, more transparent for HACH threaded line pipe is put into HACH counteract appearance, at 150 DEG C, clear up 2 hours.
Step 7: clear up after experiment terminates, carry out titration experiments, solution in transparent for HACH threaded line pipe is cooled to room temperature, adopt deionized water 3-4 time to be transferred to by solution in 50mL conical flask and adopt deionized water to be diluted to 20mL, then the ferroin indicator solution of 1 step 2 preparation is added, utilize the A seating microburette that l ferrous ammonium sulfate solution is housed to carry out titration, respectively V is designated as to actual measurement sample and blank titration volume
1and V
blank, finally according to formula COD=(V
blank-V
1) × C × 8 × 1000/V
water sample, the concrete numerical value of COD can be calculated.
Wherein, the described accurately energy-saving and cost-reducing method measuring COD is carrying out clearing up in the process of experiment, select to add the potassium dichromate standard solution of 1mL step one preparation and the sulfuric acid-silver sulfate solution of 3mL step 4 preparation, why there is such selection, be because the mensuration of amount of substance on COD of potassium dichromate standard solution and sulfuric acid-silver sulfate solution has larger impact, therefore need the numerical value that selection one is comparatively suitable.
As shown in the table, under the condition of different potassium dichromate addition, the contrast of COD measured value and standard value:
As can be seen from the above table, when COD concentration to be measured is between 50-500mg/L, when potassium dichromate addition is 1mL, the relative error of COD measured value and standard value is all within ± 7%, when addition is below or above 1.0mL, relative error is higher, especially to the mensuration of low strength COD.Therefore, when the concentration of potassium dichromate standard solution is 0.25mo1/L, select its volume to be that 1mL is to carry out the mensuration of COD.
As shown in the table, under the condition of different sulfuric acid-silver sulfate addition, the contrast of COD measured value and standard value:
As can be seen from the above table, when COD concentration to be measured is between 50-600mg/L, when sulfuric acid-silver sulfate addition is 3mL, the relative error of COD measured value and standard value is all within ± 8%, and when addition is below or above 3.0mL, relative error is more than 10%.Therefore, when this sulfuric acid-silver sulfate concentration certain (also having 5g silver sulfate in the 500mL concentrated sulphuric acid), its volume is selected to be that 3mL is to carry out the mensuration of COD.
By the described accurately energy-saving and cost-reducing mensuration measuring the complete paired samples COD of method of COD, specific embodiment is as follows:
With glucose as a standard organic solute, configuration COD concentration is the 1L strong solution of 700mg/L, then carries out diluting the COD standard solution for 40mg/L, 50mg/L, 70mg/L, 100mg/L, 200mg/L, 250mg/L, 300mg/L, 400mg/L, 500mg/L, 600mg/L and 700mg/L.Test result that COD is obtained is completed as following table (test result and relative error) according to the described accurately energy-saving and cost-reducing method measuring COD:
COD standard value (mg/L) | COD measured value (mg/L) | Test relative error (%) |
40 | 38.09 | -4.78 |
50 | 46.51 | -6.98 |
70 | 65.32 | -6.69 |
100 | 100.70 | 0.70 |
200 | 199.23 | -0.39 |
250 | 246.75 | -1.30 |
300 | 292.35 | -2.55 |
400 | 397.18 | -0.71 |
500 | 488.11 | -2.38 |
600 | 600.19 | 0.03 |
700 | 747.53 | 6.79 |
Carry out mark-on test according to the described accurately energy-saving and cost-reducing method measuring COD to test sample, and calculate recovery of standard addition, specific experiment numerical value is as shown in the table:
From above two forms, utilize the accurately energy-saving and cost-reducing COD of method to sample measuring COD provided by the invention to measure, its test relative standard deviation is below 7%, and the sample recovery of standard addition of this method is between 90% ~ 98% simultaneously.
Utilize the method can measure 40-700mg/L COD, because sampling amount is less during test, working sample is needed fully to mix, and do 3 Duplicate Samples, every 20min, transparent for HACH threaded line pipe taking-up is slightly mixed in digestion process simultaneously, HACH transparent threaded line pipe should be rinsed when being shifted in 50mL conical flask by digestion solution and guarantee that whole digestion solution enters in conical flask for more than 3 times.
The method of accurately energy-saving and cost-reducing mensuration COD provided by the invention is compared with traditional COD method of testing, and sampling amount and digestion solution equivalent reduce 90%, and waste liquid amount decreases 90%, electricity charge reduction 70%; Compared with HACH COD method, the transparent threaded line pipe of HACH can be repeatedly used, exempt transducer wall ' s abrasion situation to the impact of measurement result, reduce testing cost and ensure that result has higher accuracy rate; The method is accurate, convenient, safety and environmental protection.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.
Claims (7)
1. accurately save energy and reduce the cost and measure a method of COD, it is characterized in that, comprise the following steps:
Step one: compound concentration is the potassium dichromate standard solution of 0.25mo1/L;
Step 2: preparation ferroin indicator solution, is dissolved in phenanthroline and ferrous sulphate in deionized water, and dilutes;
Step 3: preparation l ferrous ammonium sulfate solution;
Step 4: the sulfuric acid-silver sulfate solution of preparation 1%, adds 5g silver sulfate in the 500mL concentrated sulphuric acid;
Step 5: the l ferrous ammonium sulfate solution in step 3 is demarcated, accurate absorption 1mL potassium dichromate standard solution is in 50mL conical flask, be diluted with water to 20mL, slowly add the 3mL concentrated sulphuric acid, shake up, after cooling, add 1 ferroin indicator, l ferrous ammonium sulfate solution is placed in A seating microburette and carries out titration, record titration volumes is V
0, the concentration of l ferrous ammonium sulfate solution is C=0.25 × 1/V
0;
Step 6: carry out clearing up experiment, gets the transparent threaded line pipe of HACH, is weighed into 0.04g mercuric sulfate, add 2mL water sample, record V
water sample, add the potassium dichromate standard solution of 1mL step one preparation and the sulfuric acid-silver sulfate solution of 3mL step 4 preparation simultaneously, more transparent for HACH threaded line pipe put into HACH counteract appearance, at 150 DEG C, clear up 2 hours;
Step 7: clear up after experiment terminates, carry out titration experiments, solution in transparent for HACH threaded line pipe is cooled to room temperature, deionized water is adopted to be transferred to by solution in 50mL conical flask and to be diluted to 20mL, then the ferroin indicator solution of 1 step 2 preparation is added, utilize the A seating microburette that l ferrous ammonium sulfate solution is housed to carry out titration, respectively V is designated as to actual measurement sample and blank titration volume
1and V
blank, finally according to formula COD=(V
blank-V
1) × C × 8 × 1000/V
water sample, the concrete numerical value of COD can be calculated.
2. a kind of accurately energy-saving and cost-reducing method measuring COD as claimed in claim 1, it is characterized in that: the process for preparation of described potassium dichromate standard solution is: take and be dissolved in deionized water at 120 DEG C of oven dry benchmark of 2 hours or high-quality pure potassium dichromate 12.258g in advance, move into 1000mL volumetric flask, be diluted to graticule, then shake up.
3. a kind of accurately energy-saving and cost-reducing method measuring COD as claimed in claim 1, is characterized in that: the process for preparation of described ferroin indicator solution is: take 1.485g phenanthroline and 0.695g ferrous sulphate is dissolved in deionized water, is diluted to 100mL.
4. a kind of accurately energy-saving and cost-reducing method measuring COD as described in claim 1 or 3, is characterized in that: described ferroin indicator solution is stored in brown bottle.
5. a kind of accurately energy-saving and cost-reducing method measuring COD as claimed in claim 1, it is characterized in that: the process for preparation of described l ferrous ammonium sulfate solution is: take 39.5g iron ammonium sulfate and be dissolved in deionized water, slowly add the 20mL concentrated sulphuric acid while stirring, move into after cooling in 1000mL volumetric flask, add and be diluted to graticule, and shake up.
6. a kind of accurately energy-saving and cost-reducing method measuring COD as claimed in claim 1, is characterized in that: the precision of described A seating microburette is 0.01mL.
7. a kind of accurately energy-saving and cost-reducing method measuring COD as claimed in claim 1, is characterized in that: the model of the transparent threaded line pipe of described HACH is 16mm × 100mm.
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Cited By (7)
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CN105548160A (en) * | 2015-12-10 | 2016-05-04 | 苏州国环环境检测有限公司 | Method for testing chemical oxygen demand of water sample through bichromate method |
CN108287213A (en) * | 2018-01-31 | 2018-07-17 | 天津亿利科能源科技发展股份有限公司 | The Portable bottle agent quickly detected suitable for the high chlorine root sanitary sewage COD of production platform |
CN110554031A (en) * | 2018-06-04 | 2019-12-10 | 财团法人交大思源基金会 | Colorimetric card, test set and method for judging chemical oxygen demand in water and wastewater |
CN112147272A (en) * | 2020-11-02 | 2020-12-29 | 北京市理化分析测试中心 | Method for detecting activated sludge COD (chemical oxygen demand) by using high-precision photothermal potential analyzer |
CN112881591A (en) * | 2021-01-15 | 2021-06-01 | 南京杰思尔环保智能科技有限公司 | Water sample COD concentration nonlinear decoupling control method based on differential geometric feedback control |
CN115266699A (en) * | 2022-07-30 | 2022-11-01 | 河海大学 | Method for measuring content of organic pollutants in industrial sewage |
CN115684461A (en) * | 2021-07-21 | 2023-02-03 | 中蓝长化工程科技有限公司 | Method for determining COD (chemical oxygen demand) in water by rapid digestion-volumetric method |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
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CN105548160A (en) * | 2015-12-10 | 2016-05-04 | 苏州国环环境检测有限公司 | Method for testing chemical oxygen demand of water sample through bichromate method |
CN108287213A (en) * | 2018-01-31 | 2018-07-17 | 天津亿利科能源科技发展股份有限公司 | The Portable bottle agent quickly detected suitable for the high chlorine root sanitary sewage COD of production platform |
CN110554031A (en) * | 2018-06-04 | 2019-12-10 | 财团法人交大思源基金会 | Colorimetric card, test set and method for judging chemical oxygen demand in water and wastewater |
US11474091B2 (en) | 2018-06-04 | 2022-10-18 | National Yang Ming Chiao Tung University | Color chart, test kit, and method of estimating chemical oxygen demand of water |
US11808749B2 (en) | 2018-06-04 | 2023-11-07 | National Yang Ming Chiao Tung University | Method of estimating chemical oxygen demand of water |
CN112147272A (en) * | 2020-11-02 | 2020-12-29 | 北京市理化分析测试中心 | Method for detecting activated sludge COD (chemical oxygen demand) by using high-precision photothermal potential analyzer |
CN112147272B (en) * | 2020-11-02 | 2022-06-07 | 北京市理化分析测试中心 | Method for detecting COD (chemical oxygen demand) of activated sludge by using high-precision photo-thermal potential analyzer |
CN112881591A (en) * | 2021-01-15 | 2021-06-01 | 南京杰思尔环保智能科技有限公司 | Water sample COD concentration nonlinear decoupling control method based on differential geometric feedback control |
CN115684461A (en) * | 2021-07-21 | 2023-02-03 | 中蓝长化工程科技有限公司 | Method for determining COD (chemical oxygen demand) in water by rapid digestion-volumetric method |
CN115266699A (en) * | 2022-07-30 | 2022-11-01 | 河海大学 | Method for measuring content of organic pollutants in industrial sewage |
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