Total Organic Carbon (TOC) portable TOC analyzer. TOC analyzer is the total organic carbon analyzer. A comprehensive indicator of the total amount of organic matter in a water body in terms of carbon content. E H TOC can be used very directly to express the total amount of organic matter. Therefore, it is used as an important reference index to evaluate the degree of organic pollution in water.
TOC analyzer is:
first oxidizes the carbon of organic matter in the water into carbon dioxide, eliminates the interference factors, and then measures it by the carbon dioxide detector, and then converts the carbon dioxide gas content into the concentration of organic matter in the water by data processing. After continuous research and experiment, the TOC detection method has gradually become convenient and accurate from the traditional complex technology.
TOC analyzer are as follows:
1. wet oxidation (persulfate)-Nondispersive Infrared Detection (NDIR) Laboratory Type TOC and Autosampler
this method, the sample to be tested is treated with phosphoric acid to remove inorganic carbon before oxidation, and then the concentration of TOC is measured. Most of the modern TOC continuous analyzers are wet oxidation. Wet oxidation is not sufficient for complex water bodies (such as humic acid, high molecular weight compounds, etc.), so it is not suitable for water bodies with high TOC content, but it is possible for regular water bodies such as surface water.
2. high temperature catalytic combustion oxidation-Non-Dispersive Infrared Detection (NDIR)
the application time of high temperature catalytic combustion oxidation is much later than that of wet oxidation, because the high temperature combustion is relatively complete, it can be applied to rivers, sea water and industrial wastewater with heavy pollution.
3. UV oxidation-Non-Dispersive Infrared Detection (NDIR)
the same way as wet oxidation, but using the principle of ultraviolet light (185nm) irradiation, inorganic carbon is removed before the sample enters the ultraviolet reactor to obtain more accurate results. Ultraviolet oxidation method, for granular organic matter, drugs, protein and other high content of TOC is not applicable, but can be used for raw water, industrial water and other water bodies.
4. Ultraviolet (UV)-wet (persulfate) oxidation-non-dispersive infrared detection (NDIR)
this way is the synergistic effect of UV oxidation and wet oxidation, complement each other and promote each other, and the effect of oxidation degradation is better than any of them. For UV oxidation can not be used in high content TOC water, the synergy between the two can measure the heavy pollution of water. Because of its strong applicability and wide range of measurable characteristics, it has high popularity and mature technology.
5. resistance method
This method is a technology that has been applied in recent years. Its principle is to measure the difference of resistivity of the sample before and after ultraviolet oxidation under the premise of temperature compensation. However, this method has strict requirements on the source of the measured water body, and can only use relatively clean industrial water and pure water, with a single application direction.
6. ultraviolet method
ultraviolet absorption spectrum can be traced back to 1972. Dobbs et al. studied the linear relationship between ultraviolet absorbance value (A) at 254nm and TOC of secondary effluent and river water from urban sewage treatment. After decades of development, due to the advantages of fast, non-contact measurement, good repeatability and low maintenance, the application of this method has developed rapidly.
7. conductance method
The main device involved in this method is a conductivity cell, which consists of a reference electrode, a measuring electrode, a gas-liquid separator, an ion exchange resin, a reaction coil, and a NaOH conductivity liquid. The advantages of conductivity cells are low price, easy to popularize, but poor stability.
8. Ozone Oxidation
Taking advantage of the strong oxidation of ozone, ozone oxidation is used as the detection technology of TOC, which has fast reaction speed, no secondary pollution and high application value. Therefore, the application prospect of this method is very considerable.
9. ultrasonic cavitation sonoluminescence
sonoluminescence has become a booming research field, and the study of sonoluminescence has been involved in the field of environmental protection, and relevant scholars in China have done a lot of work in basic research and applied research. In recent years, this unique method has been recognized by experts. It has the advantages of no secondary pollution, no need to add reagents, simple equipment, etc.
10. supercritical water oxidation
suitable for applications with high salt content, ultra-zero water oxidation (Supercritical Water Oxidation-SCWO) technology was originally used to treat large volumes of wastewater, sludge and contaminated soil. It is now used in commercial laboratory TOC analyzers. When the temperature and pressure of the injection water are raised above the critical point of water (375°C and 3,200psi), the organic waste is quickly and completely oxidized by the oxidant in the water. The characteristics of supercritical water can make organic carbon extremely efficient and rapid oxidation to carbon dioxide, even if there are chlorides and other inorganic substances that will cause negative interference when using non-supercritical oxidation methods.