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Rapid determining method of COD by photocatalytic digestion

A rapid determination and photocatalytic technology, applied in the direction of material excitation analysis, etc., can solve the problems of unsuitable rapid determination, influence on optical detection, and difficult preparation, etc., and achieve the effect of improving oxidation efficiency, easy operation of the method, and high reaction sensitivity

Inactive Publication Date: 2010-10-06
CHONGQING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The powder is to disperse the photocatalyst particles in the solution, and the thin film is to load the photocatalyst on other solid substances; the former needs to be filtered or centrifuged to separate the photocatalyst during the measurement because the powder affects the optical detection, while the latter is difficult to prepare and has low oxidation efficiency. Low, these are not suitable for rapid on-site determination

Method used

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  • Rapid determining method of COD by photocatalytic digestion
  • Rapid determining method of COD by photocatalytic digestion
  • Rapid determining method of COD by photocatalytic digestion

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] The comparison of the inventive method and the national standard dichromate method oxidation rate and the mensuration of actual water sample and simulated water sample:

[0022] In the present embodiment, the concentration of nano photocatalyst is 0.003g / L and the particle size is 5nm TiO 2 Powder, the colored oxidant is Ce(SO 4 ) 2 , the acidic medium uses H with a concentration of 1mol / L 2 SO 4 , the three form a composite system. At room temperature, use a 3W low-power ultraviolet light to illuminate the water sample for 10 minutes after oxidation and digestion for spectral detection. The scanning spectrum is shown in the attachment figure 1 , with 1-20mg / L potassium hydrogen phthalate solution as the standard solution, establish a standard curve, and measure the COD value of the sample.

[0023] The higher the oxidation rate of the oxidative digestion method, the more complete the oxidative digestion of the water sample, and the closer the measurement result is ...

Embodiment 2

[0038] This embodiment measures the actual water sample and the simulated water sample:

[0039] In the present embodiment, the concentration of nano photocatalyst is 0.030g / L and the particle size is 5nm TiO 2 Powder, colored oxidant chooses KMnO with a concentration of 0.4mmol / L 4 , the acidic medium uses H with a concentration of 1mol / L 2 SO 4 , the three form a composite system. Under room temperature, use a 3W low-power ultraviolet light to irradiate, oxidize and digest the water sample for 10 minutes, then perform spectral detection, and use 1-60mg / L potassium hydrogen phthalate solution as the standard solution to establish The standard curve was used to determine the COD value of the sample.

[0040] Chloride ion (Cl - ) has obvious interference to some COD determination methods, such as the national standard dichromate method, it is necessary to add a masking agent to eliminate Cl - interference. Using this system for Cl - Concentration of 15mg / L simulated wate...

Embodiment 3

[0054] This embodiment measures the actual water sample and the simulated water sample:

[0055] In the present embodiment, the concentration of nano photocatalyst is 0.030g / L and the particle size is 5nm TiO 2 Powder, the colored oxidizing agent chooses K with a concentration of 4.8mmol / L 2 Cr 2 o 7 , the acidic medium uses H with a concentration of 1mol / L 2 SO 4 , the three form a composite system. At room temperature, use a 3W low-power ultraviolet light to irradiate, oxidize and digest the water sample for 10 minutes, and perform spectral detection. Using 1-35 mg / L potassium hydrogen phthalate solution as the standard solution, the establishment The standard curve was used to determine the COD value of the sample.

[0056] Chloride ion (Cl - ) has obvious interference to some COD determination methods, such as the national standard dichromate method, it is necessary to add a masking agent to eliminate Cl - interference. Using this system for Cl - Concentration of ...

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Abstract

The invention provides a novel rapid determining method of COD by photocatalytic digestion, which adopts a compound system combined by colored oxidant and nano-photocatalyst in acidic medium to carrying out illuminating oxidation digestion for water samples, and realizes the determination of COD by optically detecting the consumption of the colored oxidant, wherein the colored oxidant is of an oxidation substance which has absorption and good optical stability in an ultraviolet visible range, and the nano-photocatalyst is of a nano-size semi-conductor material which can absorb light energy and generate electron-hole pairs. In the process of photocatalytic digestion, the colored oxidant not only oxidizes reducing substances in water and receives photo-induced electrons, and the consumption of the colored oxidant corresponds to the amount of COD. The colored oxidant and the nano-photocatalyst are combined to generate extremely strong oxidation efficiency, and can oxidize a plurality of reducing substances, so that the oxidation digestion is quickly and efficiently carried out at room temperature under non-concentrated acid conditions. The invention can solve the problems that the existing determining method of COD has complicated process, time and energy consumption, requirement for high temperature and concentrated acid conditions, and can not realize rapid field determination.

Description

technical field [0001] The invention relates to the technical field of environmental monitoring, in particular to a method for measuring chemical oxygen demand (COD). Background technique [0002] Chemical Oxygen Demand (Chemical Oxygen Damand, COD) refers to the amount of oxidant consumed when a certain strong oxidant is used to treat water samples under certain conditions, which is converted into the mass concentration of oxygen, reflecting that the water body is polluted by reducing substances. It is one of the important indicators to comprehensively evaluate the degree of water pollution. [0003] The determination of COD first needs to oxidize and digest the reducing substances in the sample, and most organic substances are difficult to oxidize and digest, so oxidative digestion is the focus and difficulty of COD determination. The existing COD determination method is mainly the dichromate method, which is currently the standard method adopted in my country and the wor...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/63
Inventor 莫志宏刘智温志渝向小娥魏文静
Owner CHONGQING UNIV
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