Method of express-identification of cobalt (ii) and copper (ii) in water-salt solutions for environmental objects analysis

FIELD: chemistry.

SUBSTANCE: invention can be used for semi-quantitative determination of cobalt (II) and copper (II) concentration is natural, sewage waters and various liquids under field conditions. Method includes filling glass tube with internal diameter 0.5 cm with Na-form of cation exchanger KB-2E-10 with weight 0.2 g, with further filling with analysed solution, which contains added to it sodium nitrate with concentration 1 mole/l and calcium nitrate to create medium, and estimation of cobalt and copper concentration by length of coloured zone of cation exchanger with the following content of components after tube filling, wt %: cation exchanger KB-2E-10 - 0.8; sodium nitrate - 8.5; calcium nitrate - 0.25; water - the remaining part.

EFFECT: increase of accuracy and reliability and simplification of analysis.

1 ex, 2 dwg

 

The invention relates to the field of analytical chemistry, namely the development of rapid tests, and can be used for semiquantitative determination of the concentration of cobalt(II) and copper(II) in natural, waste water and various liquids in the field.

Method rapid determination of cobalt(II) and copper(II) in the presence in the aqueous solution includes a test indicator tube based on carboxylic cation exchanger KB-2E-10 to the sodium form, and as substances to create environment - nitrates of sodium and calcium.

Known (Patent RF 2223488, G01N 31/22, G01N 21/78, 10.02.2004) an indicator composition for the determination of copper(II) in aqueous solutions containing sorbent, the reagent substance to create an environment and water, characterized in that it comprises as a sorbent - anion exchange resin an-31 in the sulfate form, as an analytical reagent 4-(2-pyridylazo)-resorcinol (PAR), and as substances to create environment - sulfuric acid. The disadvantages of this indicator composition is the use of expensive reagent VAPOR, which leads to additional costs, and the lack of determination of copper and cobalt from a mixture.

Known (Patent RF 2002129681, G01N 31/22, 10.05.2004) an indicator composition for the determination of cobalt(II) in aqueous solutions containing sorbent, nitroso-R-salt, a substance to create an environment and water, otlichalis�, what contains as the sorbent cation exchanger KB-2-3T, and as substances to create environment - sodium acetate. Determination of cobalt by this method interferes with copper. Method for determination of copper and cobalt in the presence of the proposed method is unknown.

The authors Petrova V. V., Bobkova, L. A. [Test-flat tube-based macrosector carboxylic cation exchanger KB-2E for determination of impurities Co2+and Cu2+in water-salt solutions // proceedings of XIII all-Russian scientific-practical conference named after Professor L. P. Kulev of students and young scientists "Chemistry and chemical engineering in XXI century", may 14-17. 2012. S. 269-271] the described method of determination of impurities of Cu2+and Co2+at their joint presence in water-salt solutions using a test indicator tube based macrosector carboxylic cation exchanger KB-2E-10, selected as a prototype.

The disadvantages of this method are:

1. Adding a large number of background electrolyte of sodium nitrate to create an environment and, as a result, complication of the analysis.

2. The deletion of a large sample volume (100 ml), which increases the time of analysis.

3. The use of tubes with a diameter of 0.7 cm, which gives less contrast chromatographic separation zones ions of cobalt(II) and copper(II).

4. Show single� the result of the segregation of ions with the concentration of cobalt(II) and copper(II) ~30 mg/L. The ability to determine low concentrations of impurities not specified.

The object of the present invention is a method of rapid determination of cobalt(II) and copper(II) in water-salt solutions for the analysis of environmental objects to reduce the detection limit, reduce sample volume and time analysis. The technical result of the invention allows to determine the cobalt and copper at the same time without adding additional reagents. This can simplify the chemical analysis and reduce the time of the meeting.

Method rapid determination of cobalt and copper in water-salt solutions comprising a glass tube filled with Na-form cation exchanger KB-2E-10, sodium nitrate and calcium(II) for the creation of the environment, water, characterized in that is used a glass tube with an inner diameter of 0.5 cm, with a mass of cation exchange resin KB-2E-10 - 0.2 g, and the concentration of sodium nitrate is 1 mol/L. the Reagents used in the following ratio of components, wt.%:

The cation exchanger KB-2E-10 - 0,8

Sodium nitrate - 8,5

Calcium nitrate - 0,25

Water - the rest.

Copper(II) and cobalt(II) are the normalized components of natural waters. The maximum allowable concentration of Co2+in natural waters is 0.1 mg/l, a Cu2+1 mg/l. studies have shown that microsaccades carboxyl cationite KB-2E-10, synthesis�Rowan Kemerovo LLC "Tokem" on the basis of polymetacrylate and devicelog ether of diethylene glycol (DADAG) has a high affinity to ions of Co 2+and Cu2+. This allows the use of the sorbent as the active filler test indicator tubes for the determination of these ions in water-salt solutions.

For the determination of cobalt(II) and copper(II) sample analyte solution volume of 25 ml at pH ~4.5 and containing 2,125 g NaNO3and 0,059 g Ca(NO3)2passed at a rate of 1 ml/min through a glass tube with an internal diameter of 0.5 cm, filled with Na-form cation exchanger KB-2E-10 to a height of 4 cm (m=0.2 g). When passing the solution through a layer of bright grains of the resin occurs, the coloring layer of a sorbent characteristic for each ion color. The length of the colored zone depends on the concentration of the analyte. The content of ions of cobalt(II) and copper(II) in the sample solution is calculated according to the calibration graph (Fig.1), for construction of which we take aliquots of a standard solution of cobalt(II) and copper(II), is passed through the sorbent and measure the length of the painted area.

The dependence of the analytical signal (the length of the colored zone) linear in the concentration range for copper(II) - (0,95-9,53) mg/l, and cobalt(II) - (0,88-8,85) mg/l (Fig.1). Linearity is confirmed by the correlation coefficients close to unity.

The limit of detection of copper ions(II) amounts to 5.19 mg/l, and cobalt(II) - 3,15 mg/l. However, the qualitative determination of these ions is possible at the level of the MPC.

Example determine�t of copper(II) and cobalt(II) in aqueous salt solutions. In the sample analyzed solution volume of 25 ml, containing a mixture of ions of cobalt(II) and copper(II), add 2,125 g NaNO3and 0,059 g Ca(NO3)2. Adjusted the pH of the test solution to 4.5 by the addition of nitric acid or sodium hydroxide. The resulting solution is passed at a rate of 1 ml/min through a glass tube with an internal diameter of 0.5 cm, filled with Na-form cation exchanger KB-2E-10 to a height of 4 cm (m=0.2 g). When passing the solution through a layer of bright grains of the resin occurs, the coloring layer of a sorbent characteristic for each ion color. Measure the length of the colored zone of the cation exchange resin for each ion separately. The length of the colored zone depends on the concentration of the analyte. The content of ions of cobalt(II) and copper(II) in the sample solution is calculated according to the calibration equations:

- for Cu2+y=x 0,34+1,78(R2=0,99)

for Co2+: y=0.25 x+0,77(R2D =0.99),

where x is the concentration of metal ion in solution, R is the correlation coefficient.

Advantages of the invention consist in the possibility of determination of cobalt(II) and copper(II) at their joint presence in solution (Fig.2 - formation of the colored zones of ions of cobalt(II) and copper(II) to test the indicator tube-based cation exchanger KB-2E-10 with separate (a, b) and co-presence (b) in water-salt solutions) without adding additional reagents. This allows accelerated�tit chemical analysis and reduce the time of the meeting.

(Fig.2: and. the upper part of the blue color; b. top - pink V. top - blue, bottom - pink color).

Method rapid determination of cobalt and copper in water-salt solutions comprising filling a glass tube with an inner diameter of 0.5 cm Na-form cation exchanger KB-2E-10 weight - 0.2 g, with subsequent filling of the analyzed solution containing added sodium nitrate concentration of 1 mol/l and calcium nitrate to create an environment, and an estimate of the concentration of cobalt and copper along the length of the colored zone of the cation exchange resin with the following contents after filling the tubes, wt.%:
The cation exchanger KB-2E-10 - 0,8
Sodium nitrate - 8,5
Calcium nitrate - 0,25
Water - the rest.



 

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