Determination of the efficiency of oxygen removal from water from the ratio of the concentrations of sodium sulfite and the iron catalyst

Abstract

The main issue of corrosion activity is the removal of oxygen from water. Under certain conditions, inhibitors-passivators are effective. Other methods based on thermal and vacuum deaeration of water. These methods are energy-consuming and do not provide the necessary quality of water, so chemical reagents are used for deep deoxidation of water regardless of secondary pollution.
 In this work, distilled water with a certain concentration of oxygen was placed in a hermetic container. The calculated amount of sodium sulfite solution (sodium metabisulfite) was added to the water and after certain intervals the oxygen concentration in the water was recorded using an oxygen meter, the sensor of which was placed in the container before. In another series of experiments, calculated amounts of sodium sulfite and iron sulfate solutions were added to the water, the container was quickly closed and the oxygen concentration in the water was recorded at certain intervals.
 It has been shown that in distilled water at room temperature, sodium sulfite interacts very slowly with oxygen. In 1 hour, the rate of oxygen recovery increases from 27.7 % to 56.9 % when the sulfite concentration increases from 50 to 300 mg/dm3. It was established that iron (II) ions significantly accelerate the rate of oxygen reduction by sulfite already at an iron concentration of 0.1 mg/dm3 at a sulfite concentration of 50-300 mg/dm3. According to the integral kinetic curves of the 0th, 1st, 2nd, and 3rd orders, kinetic models of sulfite oxidation in distilled water with oxygen in the presence of iron ions were determined.
 It is shown that when the concentration of sulfite increases to 200, 300 mg/dm3, with an iron concentration of 0.5‑1.0 mg/dm3, the oxidation processes follow first-order reactions and their speed is determined by the oxygen concentration. When the concentration of iron and sulfite is reduced, the realization of oxidation processes according to the reactions of the 2nd and 3rd orders was noted, when the speed of the process depends not only on the concentration of oxygen, but also on the concentration of sulfite (2nd order) and iron ions (3rd order) .
 This work is aimed at solving the relevance of the problem of water deoxidation for water preparation in cooling systems. The direction of the research is very promising considering the satisfactory and effective results obtained and the inexpensive chemical reagents used. Further research will be aimed at finding ideal conditions for the reaction and finding optimal concentrations of reagents while ensuring maximum efficiency of the process, which in turn will bring mankind a solution to the problem of spending large amounts of money, chemical reagents and environmental pollution.