RU2471764C1 - Method of concentrating pyrogallol from aqueous solutions - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a method of concentrating pyrogallol from aqueous solutions, which can be recommended for analytical inspection of sewage coming in for biological treatment. The dislcosed method involves concentration of pyrogallol from aqueous solutions acidified to pH=1-5 at temperature of 20±2°C using an organic solvent of tributyl phosphate, said tributyl phosphate modifying crushed rigid polyurethane foam in weight ratio of polyurethane foam to tributyl phosphate equal to 1:(2.0-2.6).

EFFECT: method increases the concentration factor of pyrogallol and reduces consumption of organic solvent.

2 ex, 1 tbl

Description

The invention relates to the analytical chemistry of organic compounds and can be recommended for the concentration of pyrogallol in the analytical control of wastewater entering biological treatment.

The closest in technical essence and the achieved effect is the method of extraction concentration of pyrogallol from acidified aqueous solutions (pH = 1-5) at a temperature of 20 ± 2 ° C with tributyl phosphate at a ratio of aqueous and organic phases of 10: 1 [Korenman Y.I. The distribution coefficients of organic compounds. Directory. Voronezh: Voronezh state. un-t 1992. - 336 p.].

The disadvantages of the method: low concentration coefficient (K = 10), high consumption of scarce tributyl phosphate reagent (TBP).

An object of the invention is to increase the concentration coefficient, reduce the cost of analysis by reducing the consumption of an organic solvent of tributyl phosphate.

The technical task of the invention is achieved by the fact that in the method of concentrating pyrogallol from aqueous solutions, including concentrating pyrogallol from acidified to pH = 1-5 aqueous solutions at a temperature of 20 ± 2 ° C with an organic solvent tributyl phosphate, it is new that tributyl phosphate modify the crushed rigid polyurethane foam into the mass ratio of polyurethane foam: tributyl phosphate equal to 1: (2.0-2.6).

The technical result of the invention is to increase the concentration coefficient, reducing the consumption of an organic solvent of tributyl phosphate.

The method of concentrating pyrogallol from aqueous solutions is as follows.

Polyurethane foam (PUF), which is a waste from the production of building materials, is crushed, sieved through a sieve with a mesh size of ≤2-4 mm. TBP is applied to the surface of the obtained fraction, the mass fraction of which with respect to the mass (g) of polyurethane foam varies in the ratio (2.0-2.6): 1. So, if the polymer mass is 0.10 ± 0.01, then the mass of applied TBP will vary from 0.20 ± 0.01 to 0.26 ± 0.01. In 20 cm ^{3 of an} aqueous solution of pyrogallol, acidified to pH 1-5, a modified PUF is introduced, extracted with a vibrating mixer for 15 minutes. After phase separation, an equilibrium aqueous solution is selected, the content of pyrogallol in which is determined photometrically by reaction with diazotized sulfanilic acid. The optical density is measured on a KFK-2 brand photoelectrocolorimeter at a wavelength of λ = 400 nm.

The degree of extraction of pyrogallol is calculated by the formula

R = (C _ref- C _equal ) · 100 / C _ref ,%,

where C _ref and C _equal - the concentration of pyrogallol in the initial and equilibrium solution, respectively.

The coefficient of extraction-sorption concentration of pyrogallol is calculated by the formula

m = m _water / m _org

where m _water and m _org are the masses of the aqueous and organic phases, respectively.

The coefficient of extraction concentration of pyrogallol is calculated by the formula

m = m _water / m _TBP ,

where m _water and m _TBP are the mass of the aqueous phase and the mass of tributyl phosphate, respectively.

96-97% of pyrogallol passes into the organic phase compared to the initial content in the analyzed water sample, the coefficient of extraction-sorption concentration is 40.

The method of concentrating pyrogallol from aqueous solutions is illustrated by the following examples.

Example 1

Polyurethane foam is crushed, sieved through a sieve with a mesh size of ≤2-4 mm. To 20.0 cm ^{3 of the} analyzed water sample, acidified to pH 2-3, containing pyrogallol, add 0.5 g of PUF coated with TBP in a ratio of 1: 2.0 to the mass of polyurethane foam, extracted with a vibrating mixer for 15 minutes until interfacial equilibrium is established.

The degree of extraction of pyrogallol is calculated by the formula

R = (C _ref- C _equal ) · 100 / C _ref ,%,

where C _ref and C _equal - the concentration of pyrogallol in the initial and equilibrium solution, respectively.

The coefficient of extraction-sorption concentration of pyrogallol is calculated by the formula

m = m _water / m _org

where m _water and m _org are the masses of the aqueous and organic phases (TBP and PUF), respectively.

The coefficient of extraction concentration of pyrogallol is calculated by the formula

m = m _water / m _TBP ,

where m _water and m _TBP are the mass of the aqueous phase and the mass of tributyl phosphate, respectively. The analysis data are presented in the table.

Example 2

Polyurethane foam is crushed, sieved through a sieve with a mesh size of 5≤2-4 mm. To 20.0 cm ^{3 of the} analyzed water sample, acidified to pH 2-3, containing pyrogallol, add 0.5 g of PUF coated with TBP in a ratio of 1: 2.6 to the mass of polyurethane foam, extracted with a vibrating mixer for 15 minutes. Next, analyze according to example 1. The degree of extraction and the concentration coefficient is calculated analogously to example 1. The analysis data are presented in the table.

Comparative characteristics of the proposed method and prototype are given in the table.

Table Indicators Known method The proposed method by examples one 2 The coefficient of extraction-sorption concentration - 40 40 The coefficient of extraction concentration 10 60.6 55,4 The degree of extraction,% 82 96 97 The consumption of organic solvent per 1 cm ³ water samples, cm ³ 0.10 0.016 0.018

As can be seen from the table, the proposed method of concentrating pyrogallol from aqueous solutions when using polyurethane foam with TBP deposited on its surface, the mass fraction of which with respect to the mass (g) of polyurethane foam varies in the ratio (2.0-2.6): 1 makes it possible to extract pyrogallol up to 96-97%.

It is economically unprofitable to increase the mass of TBP by more than 2.6 parts to 1 part of polyurethane foam, which leads to its partial washing out from the surface of polyurethane foam. The decrease in the mass of TBP less than 2.0 parts to 1 part of PUF leads to a significant reduction in the degree of extraction.

The method of concentrating pyrogallol from aqueous solutions allows you to:

- increase by 4 times the coefficient of extraction and sorption concentration and 6 times the coefficient of extraction concentration;

- reduce the consumption of tributyl phosphate and the cost of analysis.

Claims (1)

A method of concentrating pyrogallol from aqueous solutions, including concentrating pyrogallol from acidified to pH 1-5 aqueous solutions at a temperature of 20 ± 2 ° C with an organic solvent tributyl phosphate, characterized in that tributyl phosphate modify the crushed rigid polyurethane foam in a mass ratio of polyurethane: tributyl phosphate, equal to 1: 2.0-2.6).