Determination method for trace thallium in high-salt waste water

Abstract

The invention specifically relates to a determination method for trace thallium in high-salt waste water, which belongs to the technical field of heavy metal detection. The determination method for trace thallium in high-salt waste water comprises the following steps: (1) pretreating a waste water sample by using a continuous impurity removal and enrichment method consisting of procedures of extraction, washing, reverse extraction, pH value adjustment of an extraction solution, extraction, washing and reverse extraction; (2) drafting a standard work curve of thallium; (3) detecting the absorbance of the pretreated to-be-detected waste water sample through graphite furnace atomic absorption; and (4) calculating the concentration of the sample according to standard absorbance-concentration relation. According to the invention, extractant used in the method is regenerable and reusable; an added-standard recovery rate reaches 98 to 102%, and a detection limit value is up to 0.1 [mu]g / L, so emission standard detection requirements on thallium in industrial waste water are met; and a blank in determination methods for trace thallium in high-salt waste water is filled in.

Description

technical field [0001] The invention belongs to the technical field of heavy metal detection, and in particular relates to a method for determining trace thallium in high-salt wastewater. Background technique [0002] Thallium (Tl) is a typical, highly dispersed rare heavy metal element that is both lithophilic and sulfophilic in geochemistry and crystallography. According to reports, the annual production and use of thallium in the world is less than 15 tons, and the annual production of thallium by industry is about 2000-5000 tons, which is far greater than the demand, so there is no market condition for making products. At present, 56 kinds of thallium minerals have been reported in the world, and these minerals are mainly associated with other mines, especially sulfide ores. Besides iron oxide ore, the iron that we demand the most is pyrite; while non-ferrous metals such as copper, lead, zinc, antimony, nickel (associated in copper) and other non-ferrous metals that are...

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Problems solved by technology

Most of the spectrophotometric methods are determined by the means of separation and enrichment of organic solvents, which are mainly suitable for the analysis of constant and semi-trace thallium in water, but their sensitivity is low; electrochemical methods have many interference factors, poor stability and reproducibility; electrothermal atomic absorption Spectrometry (ETAAS) has high sensitivity, less sampling, and is easy to operate, but it is seriously interfered by the matrix; mass spectrometry ICP-MS is a plasma mass spectrometry test technology developed in the 1980s, which provides extremely low detection limited, extremely wide dynamic range, simple spectral lines, less interference, high analysis precision, fast analysis speed, strong anti-interference ability, and high sensitivity, it is widely used in the detection of thallium in geology and the environment, but when it is used When detecting thallium in high-salt wastewater: there is noise and background drift increases, the matrix effect produced by coexisting salts will reduce the sensitivity of the element to be measured, and the ionization of high-salt wastewater in the high-temperature ion torch seriously erodes the torch tube, making it recombined in In the wall of the torch tube, white non-transparent substances are formed, which makes the quartz torch tube brittle and easy to break, reducing the service life of the torch tube. The spray rate is gradually reduced, or even blocked. At the same time, expensive equipment investment and operating costs make it difficult to popularize; while the measurement method (graphite furnace atomic absorption spectrophotometry) recommended in the national standard (GB / T5750.6-2006) adopts direct However, for the determination of trace thallium in high-salt wastewater, there are some defects such as poor sample stability and repeatability, low recovery rate of standard addition, cumbersome pretreatment process, and many types of chemicals used.

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