Shen ChangHong Cod analyzer is a kind of chemical oxygen demand analyzer. The measuring principle is rapid catalytic method (chromium method). With the application of cold light source display technology, the service life of the light source lamp is up to 100000 hours, and the switching of the measuring parameter light path becomes automatic from manual, eliminating the error factor of human rotation. In the laboratory and field, the COD of sewage can be measured quickly and accurately. It is the necessary experimental equipment for environmental monitoring station, environmental engineering technicians and enterprise laboratory. So, what are the using methods of COD Analyzer?
Using method of COD analyzer
1、 Closed digestion colorimetry method (tube test)
The method can be used to measure the chemical oxygen demand of surface water, domestic sewage and industrial waste water, and different concentrations of oxidants can be selected according to the concentration of chemical oxygen demand.
Measuring range
Basic range: 5.0-200mg/l (CODcr_ L), 200-1000mg / L (CODcr_ M), 1000-2000mg / L (CODcr_ H);
Extension range: 1000-5000mg / L, 2000mg / L - 10000mg / L, 10000-20000mg / L
Measuring principle
Add a certain amount of potassium dichromate into strong acid solution as oxidant. Under the action of special composite catalyst, potassium dichromate was heated at 165 ℃ for 15 minutes, then it was reduced to trivalent chromium by organic matter in water. The content of hexavalent chromium / trivalent chromium ion was measured at wavelength 420nm (low range) or 610nm (medium / high range), and then the mass concentration of oxygen consumption was converted according to the content of hexavalent chromium / trivalent chromium ion.
2、 Closed digestion Colorimetry (dish test)
This method can determine the chemical oxygen demand in surface water, domestic sewage and industrial wastewater, and select different concentrations of oxidants according to the concentration of chemical oxygen demand.
measuring range
Basic measurement range: 5.0-100mg/l, 100-1000mg / L, 1000-2000mg / L;
Extended measurement range: 1000-10000mg/L, 10000-20000mg/L
measuring principle
Add a certain amount of potassium dichromate into strong acid solution as oxidant. Under the action of special composite catalyst, potassium dichromate was heated at 165 ℃ for 10 minutes, then it was reduced to trivalent chromium by organic matter in water. The content of hexavalent chromium / trivalent chromium ion was measured at wavelength 420nm (low range) or 610nm (medium / high range), and then the mass concentration of oxygen consumption was converted according to the content of hexavalent chromium / trivalent chromium ion.
3、 Closed digestion Colorimetry method(preformed tube)
The method can be used to measure the chemical oxygen demand of surface water, domestic sewage and industrial waste water, and different concentrations of oxidants can be selected according to the concentration of chemical oxygen demand.
measuring range
Basic measurement range: 5.0-200mg/l, 200-1000mg / L, 1000-2000mg / L;
Extended measurement range: 1000-5000mg / L, 2000mg / l-10000mg / L, 10000-20000mg / L
measuring principle
Add a certain amount of potassium dichromate into strong acid solution as oxidant. Under the action of special composite catalyst, potassium dichromate was heated at 165 ℃ for 15 minutes, then it was reduced to trivalent chromium by organic matter in water. The content of hexavalent chromium / trivalent chromium ion was measured at wavelength 420nm (low range) or 610nm (medium / high range), and then the mass concentration of oxygen consumption was converted according to the content of hexavalent chromium / trivalent chromium ion.
Analysis steps of COD (chemical oxygen demand) micro reflux method of Shenchang Honghong:
(1) Preparation of COD reagent and water sample
Put the reagents needed for COD analysis into each cod tube, add a proper amount of water sample according to the instructions, and then tighten the cap.
(2) Water sample digestion
Put the digestion colorimetric tube with added water sample and reagent into ds-16b / 20B / 25B / 36B cod digester, select the appropriate digestion temperature and digestion time according to the requirements of reagent for thermal reflux. After the digestion process, take out the COD test tube from ds-16b / 20B / 25B / 36B digester and cool it to room temperature.
(3) COD (chemical oxygen demand) colorimetric determination
Shenchanghong's COD analyzer (qcod-3m / cn-201a / cnp-301 / cnpn-401 / mulp-8c / pmulp-8, etc.), in the main menu, select the corresponding COD (chemical oxygen demand) test program, do not need to re-establish the standard curve, just put the digested COD reagent test tube into the instrument to read the COD value expressed in concentration units, and save the record results.
Brief introduction of COD micro reflux analysis system of shenchanghong
The micro reflux analysis system of COD (chemical oxygen demand) provided by shenchanghong includes the main body of COD analyzer, digester and matched cod reagent.
(1) Instrument host: according to the needs of different customers, shenchanghong company can provide a variety of models of COD analyzer to measure COD (chemical oxygen demand).
(2) Ds-16b / 20B / 25B / 36B digester is a digestion device developed by shenchanghong. It can be used for the digestion of COD (chemical oxygen demand), total chromium, total nitrogen, total phosphorus and other water samples. The digestion time and temperature can be selected in the range of normal temperature - 200 ℃ and 1 - 9999 minutes respectively.
