SU1585323A1 - Method of determining solubility of oxygen in aqueous solutions - Google Patents

Abstract

The invention relates to methods for analyzing complex media and can be used in biochemical studies, in the microbiological, medical and food industries, in wastewater treatment. The purpose of the invention is to improve the accuracy of determining the solubility of oxygen in aqueous solutions, including fermentation media. To do this, the test solution is purged with an oxygen-containing gas mixture until it is saturated with oxygen. Then, the aqueous solution is diluted with distilled water that does not contain oxygen, and again purged with the same gas mixture until saturation. In this case, the partial pressure of the dissolved oxygen is measured, and the solubility of oxygen is determined by the difference in the measured partial pressures in a dilute aqueous solution before and after purging the gas mixture. 1 il.

Description

The invention relates to methods for analyzing complex media and can be used in biochemical research, in the microbiological, medical and food industries, in wastewater treatment.

The purpose of the invention is to improve the accuracy of determining the solubility of oxygen in aqueous solutions, including complex solutions of medium concentrations of sucrose and glucose (10-25%).

This goal is achieved by

The HTO aqueous solution is purged with a gas mixture containing oxygen until it is saturated with oxygen, then the aqueous plant iBop is diluted with distilled water not containing oxygen, and the diluted aqueous solution is again blown

the same gas mixture. At the same time, the partial pressure of dissolved oxygen in a dilute aqueous solution is measured before and after purging with a gas mixture, and the determination is dissolved ;;. Bridges of oxygen are carried out according to the difference between the measured partial pressures of oxygen.

In the implementation of the proposed method, a gas mixture containing cyblon is purged through an aqueous solution. At the same time, a constant pressure is maintained in the vessel containing the test solution. According to Henry's law, the solubility of a gas is determined by the formula

 n;

(one)

where C is the concentration of gas in the liquid

with saturation; g p - partial pressure of gas in

liquids at saturation; H is the Henry constant, eavis shee on temperature, composition and concentration of substances dissolved in a liquid.

The dependence of C on the concentration of solutes in water is close to linear (Fig. 1) and can be described with small errors by a linear equation of the type

 -,

(2) 2

where C, Cg is the gas concentration at

saturation in a liquid at a concentration of dissolved substances, respectively, S and Sg;

Si- n С „a. With t

Cqn is the concentration of gas when distilled water is consumed. If the solution is diluted with a clean plant without dissolved gas and without access of free gas, then the balance of the gas in the solution is

  H, p ,, (3)

where P ,, is the partial pressure of the dissolved gas in the solution after dilution with water to a concentration of the dissolved substances S ,.

By converting these three equations,

(four)

where C. is the solubility of gas in an undiluted solution at an appropriate temperature and pressure.

Example. Determining the solubility of the Q in oxygen in the fermentation medium.

The molasses fermentation medium was studied during the cultivation of baker's yeast. The medium filtered from the yeast, at a concentration of 8.3% lo sugar, was placed in a temperature-controlled closed vessel in which the pressure was maintained at 1.05 at. The oxygen partial pressure was measured using a low-liable galvanic sensor. The fluid was purged with air until the partial pressure of oxygen in the fluid stabilized. After that, without air access, the same amount of distilled water without dissolved oxygen was added to the liquid, the partial pressure of dissolved oxygen was recorded, and the liquid was again flushed with air to saturate the medium with oxygen. At this time, to remove oxygen from distilled water, it was boiled, placed in a column through which inert gas was blown. The thermostated vessel and the column were combined and the vessel was filled with distilled water to the top.

The partial pressure in the diluted liquid before the second air blowing was 0.455 from that measured after air blowing. The solubility of oxygen at 30 C and the tabular value of Sol 2,456 xyu mol / l was equal to

with

J j aq /

 2.456-1

one

0.455

- one

(P1) 1 Pr

 2.05-, 10 mol / l

Claims (1)

The proposed method provides an increase in accuracy by an average of 11.7%. In addition, the implementation of the method does not require sophisticated equipment, therefore it is cheaper and more reliable than the PROTOTYPE. Invention Formula A method for determining the solubility of oxygen in aqueous solutions, including blowing them with an oxygen-containing gas mixture to oxygenation, characterized in that, in order to increase accuracy, the oxygenated aqueous solution is diluted with distilled water not containing dissolved oxygen, the partial pressure of the dissolved oxygen is measured. oxygen, the diluted aqueous solution is again purged with the same gas mixture and the partial pressure of the dissolved oxygen is measured, the difference between the partial The pressure in a dilute aqueous solution before and after purging the gas mixture, and determining the solubility of oxygen was performed by the difference value set. / " f.