New online UV spectrum water analyzer principle

In view of the increasing demand for environmental protection and the increasing pollution of water quality, the state has set standards for the content of multiple water pollutants. There are two main types of water quality parameters that are widely used: One is the direct reflection of specific components in water, such as the concentration of metal ions; the other is called replacement parameters, such as COD, BOD, TOC, and so on. The replacement parameters can easily and quickly reflect the physical, chemical and microbiological characteristics of water.

Many research institutions and professional manufacturers at home and abroad are studying how to determine these water quality parameters online. At present, the main technical principles of the online automatic analyzer include chemical titration, electrochemical measurement, visible and ultraviolet spectrophotometry [7]. The principle of the first method is to determine the content of water quality parameters by chemical titration. Its disadvantages are long measuring time, complicated operation and maintenance, high running costs, and secondary pollution at the same time. The principle of the second method is to use the organic substance in water to be oxidized on the surface of the working electrode. At the same time, the working electrode will have a current change. When the potential balance of the working electrode, the current change has a linear relationship with the water quality parameter. Water quality parameters can be measured by calculating current changes. Its main features are fast measurement, simple instrument structure and no secondary pollution. The disadvantage is that there is a linear relationship between the change of the electrode current generated by different electrochemical methods and one of the replacement parameters, and there is a nonlinear relationship with other water quality parameters. Therefore, an on-line analyzer based on electrochemical method can only measure one kind of water quality parameter [2]. The third method is a method based on the absorption law to quantitatively analyze the degree of absorption of the characteristic electromagnetic radiation by molecules or ions of the measured substance. Experiments have confirmed that UV absorbance can reflect the degree of organic pollution in water, especially for a large class of aromatic organic compounds and double bond organics in water. Many data also show that the UV absorbance has some correlation with some major water quality replacement parameters [4]. Therefore, it is of great theoretical and practical significance to obtain water quality parameters by analyzing UV absorbance. The article introduces a new type of online UV spectrometer water quality analyzer. Using ultraviolet spectrophotometry as the principle, it collects the full waveband spectrum of the water sample in the ultraviolet region. By analyzing the correlation of the spectral data, the characteristic spectrum in the full spectrum is obtained. Then, the algorithm of intelligent software was used to analyze the relationship between the spectrum and various water quality parameters, and a related guessing model was established. The experimental results show that the water quality analyzer has the characteristics of fast measurement speed, high precision, good tracking performance and easy operation, and it has a great advantage compared with similar products.

System Measurement Principle This instrument is a water quality analyzer based on ultraviolet spectrophotometry. The difference between the analyzer and the foreign principle is that the light source used by the foreign instrument only produces a single wavelength spectrum, which is due to UV UV254 and COD approximately linear relationship, while the relationship between other wavelengths and water quality parameters is more complex. In order not to lose useful information on water quality parameters provided by other wavelengths, the light source used in this instrument produces a spectrum of 250-470 nm. The influence of different wavelengths on the change of water quality parameters is analyzed by intelligent software to establish a relationship model between the two. And many foreign instruments use more or less chemical reagents. For example, several DKK-TOA water quality analyzers belong to this type. The instrument designed by the author does not need any chemical reagents in use, so it can obtain various water quality parameters more quickly and directly. Compared with the previous water quality analyzers, this system has the advantages of fast measurement speed, good reproducibility, low cost, and no secondary pollution.