SU1059510A1 - Mercury extraction photometric determination method - Google Patents

Description

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The invention relates to analytical chemistry, in particular, the method for determining mercury, and can be used to quantify trace amounts — and in solutions, wastewater, biological objects, and others. Photometric analysis methods are known for determining small mercury contents in various products. As a rule, the methods used are related to extraction-photo metric. Definylcarbazone, copper diethyl dithiocarbaminate, basic dyes and a number of other organic substances l are used as reagents. A disadvantage of such methods is their low selectivity. The closest to the proposed technical essence and the achieved result is the extractive-photometric method for the determination of mercury using diti zone 2J. The disadvantages of this method are low selectivity, as well as the fact that platinum, gold, palladium, silver, copper, cadmium interfere with the determination of mercury, which leads to additional difficulties which imply the need to mask a large number of ions or to pre-release mercury. Extraction is a repetition several times, which leads to an increase in analysis time. Solutions of mercury dithizonate in chloroform and carbon tetrachloride are sensitive to the action of light, the reagent itself is unstable and easily oxidized. In addition, the dithizin method requires a long and complex purification of dithizone. The purpose of the invention is to increase the selectivity of the analysis. This goal is achieved by the method of extradiode photometric determination of mercury, including the extraction of a complex compound of mercury with an organic extra agent — a solution of a high molecular weight amine — and an additional extraction of a high molecular weight quaternary ammonium base with picorate. In addition, the high molecular weight amine contains 20 to 50 carbon atoms and the pic-quaternary base contains 20-60 carbon atoms. The essence of the invention is to obtain a bromide complex of mercury in a sulfuric acid medium of 10.-10 mol / l in the presence of bromide ions. The optimum concentration of bromide ions is in the range of 3-10 2 -7-10 mol / L. Lower or higher concentrations of eromide ions lead to underestimated results, due to incomplete extraction of mercury into the organic phase and can be explained by incomplete conversion of mercury to the bromide complex., At the concentration of bromide ions; 3-10 in an aqueous solution, cationic mercury complexes and a neutral complex, at concentrations of 7-1 (G mole / l, non-extractable anionic mercury complexes of higher charge are formed. When extracting a mercury bromide complex, you use an organic extractant co-molecular amines (number of carbon atoms 20-50). When the number of carbon atoms is less than 20, incomplete extraction of the bromide complex of mercury with a toluene solution of the amine occurs. Synthesis and purification of amines with the number of carbon atoms more than 50 is difficult. concentration The washing of the organic phase is carried out with an aqueous solution containing bromide ions and a buffer solution (pH 6.86), a standard buffer solution for pH-metering. The ratio of the buffer in relation to the washing solution of 1:10. At this stage, mercury is separated from bismuth, antimony, and a number of other elements that hydrolyze at a given pH. After washing, the organic phase is developed, a toluene solution of higher quaternary ammonium base in the form of picrate ion (CHAOP) is added with a number of carbon atoms in PAO 20-60, an aqueous phase containing iodide ions and alkali to create a pH of the solution. The range of carbon atoms used in the PABCO is 20-60. Less than 20 carbon atoms in the CHAOP radical leads to incomplete extraction of mercury with the CHAOPK toluene solution. Synthesis and purification of PJSC with a carbon number of more than 60 is difficult. The optimal concentration of CHAOPK 3-Yu is -310 mol / l. The use of the concentration of CHAOPK less than 10.10 narrows the concentration range for the determination of mercury, and more than 3-1СГ mol / l is not necessary. The optimum concentration of iodide is, ions 1-10 -1.3-10 mol / l. At a concentration of α-iodide ions -tlO mol / l, cationic mercury complexes and a neutral complex predominate in an aqueous solution, while at concentrations, mol / l, non-extractable anionic complexes of higher mercury are formed. The optimal alkali concentration varies within-U mol / L.

At an alkali concentration of 102 mol / l, the accompanying elements will interfere with the determination of mercury; at higher alkali concentrations of 10 mol / l, the destruction of the mercury iodide complex begins.

Under these conditions, multiple excesses of bismuth, antimony, tin, zinc, copper, lead, iron, manganese, cobalt, thallium, and gold do not interfere with the determination of mercury.

Under optimal conditions, a single extraction takes place with the quantitative extraction of mercury. The distribution coefficient does not depend on the ratio of the phases in the range from 1: 1 to 1: 100. This allows simultaneous concentration and determination of mercury from dilute solutions.

Example. 1 ml of 5-10-mol / l NaBr, 1.0 mp 0.1 mol / l H2S04f 7 ml of water and 10 ml are added to the MP of the mercury solution being analyzed.

210 toluene solution triok tilamin. Intensively line the funnel for 1 min. After separation and settling of the phases, the organic phase is taken and 1 Mp of 5–10 mol / L NaBr is added to it, 1 ml of standard buffer solution for pH-metry (pH 6.86).

The aqueous phase is then again removed, and 1 ml is added to the organic.

0.1 mol / l Nal, 1 ml 0.1 mol / l

NaOH, 8 ml of H50 and 0.1 ml of 410 mol / l of trinonyl octadecylammonium in the form of picrate ion. The funnel is shaken vigorously for 1-2 minutes. Photometry

picric acid in the aqueous phase relative to the reference solution (water) at 71 410. The amount of mercury is found on a safety schedule.

The invention makes it possible to determine mercury with high sensitivity in the presence of Sb, B-i, Fe, Co, Sn, Pb, Mg.

Claims (3)

1. METHOD FOR EXTRACTION-PHOTOMETRIC DETERMINATION OF MERCURY, including the extraction of a complex compound of mercury with an organic extractant, characterized in that, in order to increase the selectivity of the analysis, a high molecular weight amine solution is used as an extractant and extraction is carried out with picrate of high molecular weight quaternary ammonium base. 2. The method of pop. 1, characterized in that the high molecular weight amine contains 20-50 carbon atoms. 3. The method according to claim 1, with the fact that the picrate of the Quaternary ammonium base contains 20-60 carbon atoms. >