Method for measuring low-range COD in water body by dual wavelength internal standard method

An internal standard method, dual-wavelength technology, applied in testing water, measuring devices, color/spectral characteristics measurement, etc., can solve the problems of cumbersome devices, long detection time, unreliability, etc., and meet the requirements of reducing consistency and accuracy , reduce the detection cost and improve the accuracy

Pending Publication Date: 2018-12-07
东盛科兴环保科技河北有限公司
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Problems solved by technology

[0003] GB11914-89 This method is not suitable for salt water containing chloride ion concentration greater than 1000mg / L. When the chloride ion concentration is greater than 1000mg / L, the minimum allowable limit of COD is 250mg / L. The accuracy is not reliable below this value. In addition, this method of measuring COD will also increase the mercury-containing and silver-containing wastewater, causing secondary pollution.
HJ828-2017 improves the detection method of GB11914-89, reduces the amount of water samples and reagents to be tested by half, and adds mercury sulfate to the amount of chloride ions, which relatively reduces the secondary pollution caused by reagents, but it is still unavoidable Mercury and silver contamination, and the detection process is time-consuming and cumbersome
HJ / T70-2001 has long detection time, cumbersome equipment, complex detection process, large error in measurement results, not applicable for COD values ​​below 250mg / L

Method used

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  • Method for measuring low-range COD in water body by dual wavelength internal standard method
  • Method for measuring low-range COD in water body by dual wavelength internal standard method
  • Method for measuring low-range COD in water body by dual wavelength internal standard method

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Embodiment 1

[0021] Linear Analysis and Measuring Range Test

[0022] The measurement wavelength is selected as 425nm, the calibration wavelength is selected as 750nm, and the optical path is 2cm for linear analysis and measurement range test.

[0023] Test Conditions

[0024] Equipment: Visible spectrophotometer, COD digestion instrument, digestion tube with 10mL scale, 5mL quantifier, cold water tank, 5mL pipette, glass cuvette (20mm)

[0025] test reagent

[0026] Catalytic oxidant preparation: Weigh 0.5g potassium dichromate and 12g copper sulfate pentahydrate, add 50ml distilled water, add 100ml analytically pure phosphoric acid, slowly stir and slowly add 350ml analytically pure sulfuric acid until the solid reagent is completely dissolved, and put it in after cooling down to room temperature 5ml quantifier ready to use.

[0027] Preparation of COD standard stock solution: weigh potassium hydrogen phthalate (HOOCC) after drying at 105°C for 2 hours and cooling 6 h 4 COOK) 0.4251...

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Abstract

The invention discloses a method for measuring low-range COD in a water body by a dual wavelength internal standard method. The method involves the following steps: adding a mixed solution of sulfuricacid and phosphoric acid of potassium dichromate and copper ions to a water sample, digesting at temperature of (150-165) DEG C for (10-15) min, selecting a measurement wavelength at a wavelength of(335-460) nm, and selecting a calibration wavelength at (750-900) min. The method for measuring a change in wavelength absorbance after calibration and for measuring the COD in a range of (0-250) mg / Lis established. According to the method, requirements for consistency and accuracy of oxidant addition amount for measuring the low-range COD are reduced, and the accuracy of low-range COD measurement is improved, especially technical indexes such as the measurement accuracy of the low-range measurement.

Description

technical field [0001] The present invention relates to the detection method that comprises the water quality monitoring of surface water / underground water / domestic sewage / industrial waste water or the detection method that the water body is polluted in the environmental protection field such as on-line monitoring, specifically relates to the sulfuric acid and phosphoric acid mixed solution of potassium dichromate and copper ion, in Digest at (150-165)°C for (10-15) min, select the measurement wavelength at (335-460) nm, and select the calibration wavelength at (750-900) nm. To establish a method for measuring water quality COD by measuring the change of wavelength absorbance after calibration. It is used to detect undiluted or diluted COD in (0-250) mg / L surface water, groundwater, domestic sewage and industrial wastewater that is easily oxidized. technical background [0002] COD (Chemical Oxygen Demand) is the amount of oxidant consumed when a certain strong oxidant is u...

Claims

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Application Information

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IPC IPC(8): G01N21/31G01N33/18
CPCG01N21/3151G01N33/1806
Inventor 邱娟娟周晶晶宋秒任灵芝张祖栋孙浩
Owner 东盛科兴环保科技河北有限公司
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