SU1732223A1 - Method of concentrating metals from solution - Google Patents

Abstract

The invention relates to methods for concentrating metals from a solution primarily for subsequent quantitative determination and reduces the detection limit and simplifies the process of sample preparation. The method consists in introducing a mixture of low-melting organic substances with di-2-ethylhexyl phosphoric acid into the analyzed solution and passing hydrogen sulfide until the solution is completely discolored. The precipitation proceeds in the melt of organic matter-: after cooling, the concentrate is separated in the form of a frozen tablet, which is then subjected to a quantitative analysis by the X-ray fluorescence method for lead, bismuth, nickel. Paraffin or higher carboxylic acids of the Ct-r-C fraction are used as low-melting organic substances. The limit of detection lowers 4 to q 17 s to 10%. Simplification of the sample preparation process is carried out by simultaneous concentration and sample formation. 1 hp f-ly, 1 tab. § v,

Description

The invention relates to methods for the determination of elements by the methods of physicochemical analysis, in particular, an analysis that allows to obtain an analytical signal from solid samples, X-ray fluorescence (XRF), and can be used to concentrate and determine trace elements in wastewater and industrial waters.

The known method of determining metals in the form of sulfides by the method of X-ray fluorescence analysis. Metal sulfides are obtained by precipitation with hydrogen sulfide from solutions of mineral acids, filtered using a water-jet pump through a filter paper, put on a special disc, dried, pressed and analyzed. Јlj.

The disadvantage of this method is the duration of the process associated with filtering and pressing.

The closest to the present invention is an X-ray spectral method for the determination of metal sulfides by an exchange reaction, which includes the preparation 1

3

49

Ј &

the treatment of freshly precipitated zinc sulfide as a fine powder on a collector (cellulose nitrate), obtaining the analyzed metal sulfide by an exchange reaction Not on, washing the resulting sulfide

a mixture of ethyl alcohol and water, filtering using a water-jet pump, drying the samples in a warm air flow, and then

definition

The disadvantages of the method are the duration of the sample preparation process associated with the preparation of freshly precipitated Znz, washing, filtering, drying the sample and a slight detection limit, and the accuracy of the determination is not high enough due to the fact that Zn2fHe

replaced by oversized results

part of ion ions analysis

The aim of the invention is to reduce the detection limits and simplify the process.

The proposed method for the quantitative determination of metal sulfides by the X-ray fluorescence method, which includes the preparation of metal sulfide on the reservoir, differs from the known fact that metal sulfides are obtained by precipitating them with hydrogen sulfide in solutions of mineral acids in the presence of a melt mixture of low-melting organic substances (BWL) with di-2-ethylhexyl phosphoric acid () “Paraffin or higher carboxylic acids of C, 7-СGO (IGC) fractions are used as BOW.

The use of BVO as a carrier of metal sulphides is primarily due to the fact that the substances used are good extracting agents - complexing agents for the metals being analyzed. By varying the pH of the solution, a quantitative transition of the analyzed element into the organic phase can be achieved. As the aqueous phase is saturated with hydrogen sulfide the organic anion is exchanged in the MenRn compound for the sulfide ion S2 with the formation of the corresponding metal sulfides MeS In addition9 metal cations remaining and not bound nye in organic complex form in the aqueous phase with sulfide ions corresponding metal sulphides, which as a result "

is 80 ° C),

five

0

sorption is drawn into the organic phase

The method provides a double concentration of elements from the aqueous phase, including a combination of extraction and sulfide precipitation. The detection limit of elements decreases from to CG in comparison with the known P method.

- Since the BWO have a melting point of 6 ° C, the method is carried out at an elevated temperature (60 which increases the rate of the reactions and reduces the time required to establish equilibrium in the system. When a current of hydrogen sulfide is passed, an active sparging of the gas through the aqueous solution takes place, eliminating additional mixing of the aqueous and organic phases The solidified, solid organic phase is easily separated from the aqueous solution and, after remelting, in special forms (d

5 0 mm) is a finished emitter sample for X-ray fluorescence analysis.

Example 1. In a thermostatically controlled cylindrical vessel pour

A test solution containing 1 µg / ml bismuth hydrochloride, having a pH value of 0.8-L, 9, weighed a mixture of IHC and D2ESHZH (10-20%). After the mixture has been melted (1 min), the extraction vessel is closed with a lid with a nozzle into which two tubes are inserted (one for introducing gas, the other for withdrawal). Hydrogen sulfide is passed until the solution is completely discolored (8-P min). The mixture is then poured from the vessel into a beaker, cooled, the organic phase is separated from the water as a frozen tablet, which after melting in a special form (d P mm) is a ready emitter for RF analysis. Bismuth and other metals are analyzed on a CPM-20 instrument at a voltage of 40 kV, a current of 0 mA, an exposure time of 0 s. Crystal analyzer LiF. The calibration curve is based on standard metal solutions (99.999%) in the coordinates: X-ray intensity — amount of metal in the sample, µg / ml or%. Found 9.8 µg / ml hs5

0

five

five

muta „

ii

EXAMPLE 2 The conditions are the same as in example 1 with the difference that instead of bismuth they take a solution containing 10 µg / ml of lead nitrate, the pH is set to 1, 0, and the mixture of paraffin with di-2-ethylhexyl phosphoric acid (10% .P.). Found 9.6 μg / ml lead o

EXAMPLE 3 Experimental conditions are similar to example 1 with the difference that an analyte solution containing 10 µg / ml of nickel sulphate is taken as the object of study, the pH is set to 8, and the BWO mixture is used as BOV, Found 10.1 µg / ml nickel,

PRI meer k. The conditions are the same as in Example 1 with the difference that they take 10 µg / ml of bismuth and nickel as the object of study, the pH is adjusted to 0.8-0.9, and the mixture of BCC and D2EHPA is used as BWH. 9.9 µg / ml bismuth nickel not found

Example 5 Conditions similar to Example 1, with the difference that 10 µg / ml of a hydrochloric acid solution of copper are taken as objects of research, it is established that a mixture of BCC and D2EHPA is used as BWH. Found 9.8 µg / ml copper ,,

ten

The table gives a comparative analysis of the extraction-X-ray fluorescent and sulfide-extraction-X-ray fluorescence methods for the determination of metals;

Thus, the proposed method shortens the sample preparation time, simplifies the process and reduces the metal detection limit by an order of magnitude.

Claims (1)

Invention Formula 1 ,, A method for concentrating metals from a solution, including their precipitation with hydrogen sulfide, mainly for the subsequent quantitative determination of these metals, in order to reduce the detection limits and simplify the process, the precipitation is carried out in the presence of melt a mixture of low-melting organic substances with di2-ethylhexylphosphoric acid. 2 "The method according to p. 1, differ- . y and with the fact that paraffin or higher carbolic acids of C 20 fraction are used as low-melting organic substances.