Miniaturized optical device for detecting ammonia nitrogen in water and detecting method

Abstract

The invention discloses a miniaturized optical device for detecting ammonia nitrogen in water and a detecting method, and relates to water quality detection technology. A gas-liquid separation unit comprises a bowl-shaped water tank, a tank cover, a peristaltic pump, a four-way valve and connecting pipes, wherein one end of the peristaltic pump is connected with the water tank through a first connecting pipe, the other end of the peristaltic pump is connected with one end of the four-way valve through a second connecting pipe. An optical detection unit comprises an air chamber, at least one light source, at least one photo-detector, and at least one ammonia gas sensing element, wherein the light source is located at one inner side wall of the air chamber, the photo-detector is located the other inner side wall of the air chamber and is opposite the light source, the ammonia gas sensing element is located between the light source and the photo-detector, and an upper end of the ammonia gas sensing element is fixedly connected with a top wall of the air chamber. The light from the light source vertically passes through the ammonia gas sensing element on an optical path of the light source and then is received by the photo-detector. An output end of a signal processing chip is electrically connected with subsequent devices. The device is simple in structure, small in size and wide in detection range, and the ammonia gas sensing element can be repeatedly used, and thus the device is suitable for on-site quick detection.

Description

technical field [0001] The invention relates to the technical field of water quality detection, and is a miniaturized optical water quality ammonia nitrogen detection device, which can quickly and accurately measure the ammonia nitrogen content in a water sample to be tested on site. Background technique [0002] Ammonia nitrogen in water mainly exists in the form of free ammonia and ammonium salt, and its main sources are the decomposition products of nitrogen-containing organic matter in domestic sewage under the action of microorganisms, certain industrial wastewater, such as tannery wastewater, coking wastewater, and wastewater from synthetic ammonia fertilizer plants, Farmland drainage, excess feed in aquaculture water, accumulation of large amounts of excrement from fish and shrimp, and excessive fertilization, etc. In addition, in an oxygen-free environment, nitrite present in water can also be reduced to ammonia by microorganisms. [0003] Ammonia nitrogen in water ...

AI Technical Summary

Problems solved by technology

For example, Nessler's reagent colorimetry, salicylic acid-hypochlorite colorimetry, and neutralization titration use more reagents, cumbersome operations, water samples need to be pretreated, and the test time is long, which is not suitable for on-site rapid detection. In addition, the first two colorimetric methods need to use a large spectrophotometer; although the ammonia-sensitive electrode method does not require water sample pretreatment, the electrode structure is complex, the stability is poor, it is easily disturbed, and frequent calibration is required; the gas-phase molecular absorption spectrometry Expensive spectrometers are required, and a long optical path is required to ensure high sensitivity, so it is not easy to miniaturize and portable the detection instrument, making this method unsuitable for on-site detection; the ammonia gas recovery assay uses pure water absorption Ammonia gas released by alkalization of water samples, and then adding an acid-base indicator to measure the absorbance of pure water after absorbing ammonia gas, this method also has disadvantages such as cumbersome operation and complicated equipment

In addition to the above-mentioned conventional detection methods, reagent strips and kits for the detection of ammonia nitrogen in water quality have also appeared in recent years. Although these simple methods are fast in detection speed, they have poor accuracy and are not suitable for quantitative determination.

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