Chemical Oxygen Demand (COD) refers to the amount of oxidant consumed when treating water samples with potassium dichromate as an oxidant under strong acid conditions, expressed in mg/L of oxygen. Chemical oxygen demand reflects the degree of pollution caused by reducing substances in water, including organic matter, nitrite, ferrous salts, sulfides, etc.
The microwave sealed digestion COD rapid analyzer is a device used to monitor the chemical oxygen demand of various wastewater, domestic sewage, and surface water.
Compared with the COD standard reflux method, the microwave sealed digestion COD method requires significantly fewer reagents, has strong resistance to chloride ion interference, and only takes 10 minutes for digestion, achieving the goals of saving time, energy, and water. It can be used as an equivalent method.
The instrument adopts testing methods that are basically the same as the national standard (GB11889-11915-89) for water quality vocabulary (Part 3-7) and analytical methods, as well as the CODcr potassium dichromate method and the potassium persulfate digestion spectrophotometric method for total phosphorus and total nitrogen in the "Monitoring and Analysis Methods for Water and Wastewater" (Third Edition).
The instrument adopts a microwave energy heating method with a frequency of 2450MHz. Under its action, dipole molecules in the reactants in the digestion system will rotate at high speed, forming intense friction and collision, causing the temperature of the reactants to rapidly rise, achieving the ideal effect of fast and low consumption.
The instrument also uses a closed (sealed) state for digestion. One of its advantages is that it can create a certain pressure inside the tank to quickly increase the temperature of the reaction system and shorten the digestion time; Secondly, in CODcr analysis, the effective inhibition of the oxidation of chloride ions to chlorine gas by potassium dichromate can be combined with the addition of an appropriate amount of mercury sulfate as a masking agent to determine the chemical oxygen demand of high chlorine wastewater.
2、 Technical features:
The microwave sealed digestion COD determination device uses electromagnetic waves (referred to as microwaves) with a frequency of 2450MH Z to heat the reaction solution. Under the action of high-frequency microwave energy, the molecules of the reaction solution undergo high-speed frictional motion, causing their temperature to rapidly increase. In addition, the sealed digestion method is used to rapidly increase the internal pressure of the digestion tank to about 203kPa. Therefore, not only does it shorten the digestion time, but it can also inhibit the oxidation of chloride ions to chlorine gas by potassium dichromate. If an appropriate amount of mercury sulfate is added as a masking agent, COD determination of high chlorine water can be achieved. The entire digestion process does not require cooling water, reducing the hassle of installing cold water pipes and stopping water supply.
Under the control of a microcomputer, a certain amount of potassium dichromate is used to oxidize the reducing substances in the water sample in a strong acidic solution. Excess potassium dichromate is titrated with ferrous ammonium sulfate using ferrous sulfate as an indicator to calculate the COD Cr value. The colorimetric method can also be used to directly measure the concentration of trivalent chromium in the reaction solution at a wavelength of 600nm, and obtain the COD Cr value of the water sample.
Sealed digestion, overpressure protection, safe and reliable, with a buzzer indicating completion of digestion.
1. Scope of application and main purposes
Widely applicable to environmental protection departments, water resources management departments, and public health departments at all levels for monitoring and managing water quality. It can measure the COD, total phosphorus, and total nitrogen values of various surface water, domestic sewage, and industrial wastewater.
2. Product Features
Time saving, cost saving, and reducing secondary pollution.
Ø LED displays temperature, time, and is accurate and intuitive, with a buzzer indicating completion of digestion.
Ø Adopting sealed digestion, it has the ability to resist chloride ion interference, and can measure COD values greater than 50mg/l and chloride ion contents up to 1000mg/l.
Ø Can measure low COD values below 10mg/l.
The accuracy is the same as the reflux method.
Ø Fault self diagnosis: Display fault conditions with codes, facilitating users' self diagnosis and maintenance.
Ø High temperature compensation function: It can compensate for the difference in digestion temperature caused by winter, summer environment, etc., and COD measurement is more accurate!
Ø Safety protection cover.
Other optional configurations:
3. Main technical parameters

contact information:
Company Name: Taizhou Kexin Instrument Co., Ltd
Company Address: No. 666 Huaihai West Road, Jiangyan District, Taizhou City, Jiangsu Province
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Company email: jsjykxyq@126.com