A kind of determination method of arsenic valence state

Abstract

The invention discloses a determination method of arsenic valence. The method comprises the steps of: (1) adding an extracting solution which is a mixed solution of H3PO4 and ascorbic acid into a sample to be measured, which is coal or household garbage incineration ash, soil or sludge, completely releasing the produced gas, digesting by microwave, filtering a digestion liquid, washing the residue by an extracting solution, collecting the washing liquid, mixing the extracting solution with the filtrate, and making up to volume; (2) separating trivalent and pentavalent arsenic; (3) reducing the separated trivalent and pentavalent arsenic to obtain arsenic hydride gas; and (4) determining the arsenic hydride gas obtained by reduction of arsenic in different valence, so as to obtain the content of trivalent and pentavalent arsenic in the sample to be measured. The method can achieve nondestructive extraction and fast and effective separation of trivalent and pentavalent arsenic, has the advantages of high accuracy of the determination results, simple operation, low cost on determination and equipment maintenance, and is applicable to analysis and determination of arsenic form in solid wastes such as fuel burning ash, soil and sludge.

Description

technical field [0001] The invention belongs to the technical field of arsenic form analysis in fuel combustion products, and more specifically relates to a method for determining the valence state of arsenic. Background technique [0002] The combustion of fuels such as coal, biomass and municipal solid waste is accompanied by the generation of a large amount of incineration ash. The toxic trace element arsenic present in the fuel often transforms into gaseous trivalent arsenic As under high temperature combustion 2 o 3 released into the flue gas in the form of As 2 o 3 Oxidation will generate less volatile pentavalent arsenate, which will be solidified into fly ash or bottom ash to reduce emissions to the atmosphere; at the same time, some As 2 o 3 At low temperatures, it can be captured by fly ash through physical adsorption. Therefore, arsenic mainly exists in the form of trivalent and pentavalent inorganic arsenic in fuel incineration ash. During the treatment an...

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Problems solved by technology

[0004] However, compared with water and organic samples, the arsenic in fuel incineration ash mainly exists as inorganic trivalent arsenic and pentavalent arsenic. Due to the complex physical and chemical reactions at high temperatures, the arsenic occurrence forms are very complicated and difficult to carry out Non-destructive extraction, specifically as follows: (1) The binding form of arsenic in fuel incineration ash is more stable than that in organic samples, so it is difficult to achieve efficient extraction of arsenic in ash with water, methanol or bionic solvents; (2) ) Some high-valent oxides will be generated during fuel combustion, and trivalent arsenic will be easily oxidized to pentavalent arsenic in the process of arsenic extraction, which will lead to distortion of measurement results; Substances that will affect the separation effect of arsenic in different valence states

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