Automatic online monitoring method and device for VOCs (volatile organic chemicals) in water

Abstract

The invention discloses an automatic online monitoring method and device for VOCs (volatile organic chemicals) in water, which can be used for automatically and quickly monitoring the contents and concentration of VOCs in water, and transmitting the real-time data to a remote center platform and realizing remote reverse control. The device comprises an automatic water taking device, an automatic sampling device, a purging and gathering concentrator, a gas chromatograph, a tandem type detector, an industrial controller and a data transmission module. The method and the device disclosed by the invention are fit for automatically on-line monitoring 60 volatile organic chemicals published by the method 502.2 of US EPA (Environmental Protection Agency), particularly for 29 volatile organic chemicals stipulated in Sanitary Standard for Drinking water. The method and the device have the advantages of quick speed, high monitoring sensitivity, stable and reliable performance, full-automatic monitoring and data transmission and on the like, can be applied for automatic monitoring stations, mobile emergency monitoring stations and labs.

Description

technical field [0001] The invention relates to the technical field of water quality monitoring, in particular to an automatic on-line monitoring method and device for VOCs in water. Background technique [0002] At present, the composition and concentration of VOCs (volatile organic compounds) in water are mainly detected by chromatographic technology. Due to its limited sensitivity, it is necessary to concentrate and separate the water sample to be tested before analysis and detection. Now the main concentration and separation technologies are: liquid direct Injection separation, liquid-liquid extraction, solid phase extraction, semi-permeable membrane extraction technology and headspace sampling technology, etc. [0003] The above-mentioned concentration and separation techniques have the following disadvantages: 1) The concentration and extraction process will lead to the loss of volatile organic compounds, resulting in small measurement results; 2) The concentration pro...

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Problems solved by technology

[0003] The above-mentioned concentration and separation techniques have the following disadvantages: 1) The concentration and extraction process will lead to the loss of volatile organic compounds, resulting in small measurement results; 2) The concentration process (such as liquid-liquid extraction) will introduce toxic organic solvents , causing secondary pollution; 3) At present, the concentration of volatile organic compounds in drinking water and environmental water samples is at the ng / L-μg / L level, and the volume injected into the capillary column in the chromatography is on the order of microliters, resulting in direct analysis The detection sensitivity cannot meet the requirements, and usually requires the concentration of a large volume of test samples to ensure the detection sensitivity; 4) The chromatographic analysis instruments have high requirements for installation and use conditions, and are characterized by long time consumption and strong specificity, and are difficult to achieve automation. It is difficult to meet the emergency monitoring requirements of sudden water pollution incidents, and the rapid monitoring methods for sudden water pollution are still immature

[0005] However, in the existing detection methods, the degree of automation is low, and all operations are mainly manual, including manual sampling in the early stage, instrument control in the middle processing process, and data analysis in the later stage. The whole process takes a long time , and requires professional chromatographic analysts to operate, which will inevitably lead to manual errors; at the same time, the pre-processing methods are not uniform, the equipment is complicated, and the equipment maintenance is very difficult; on the other hand, it is mainly based on single-machine detection, without Realize network interoperability and real-time data transmission

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