Synthesis of high-effective steel corrosion inhibitors in water-oil mixtures

Nikolai Gomelya,Inna Trus,Oleksandr Kyryliuk,Olena Stepova,Olena Hlushko

doi:10.15587/1729-4061.2020.194315

Abstract

It is a relevant and practically important task for environmental protection to devise effective means to protect metals against corrosion in aggressive media containing water, petroleum products, carbolic acids, and mineral salts. To stop corrosion, corrosion inhibitors are used that must be constantly improved and whose composition must be properly adjusted. The main drawback of the highly effective inhibitors based on alkyl imidazolines, a mixture of alkyl imidazolines with alkyl pyridinium and/or quaternary ammonium compounds soluble in a methanol medium, is their high prices at relatively significant consumption in the corrosive environment. This paper reports the synthesis of steel corrosion inhibitors in oil-containing aqueous environments that meet the stricter ecological and economic requirements. It has been shown that increasing the level of water mineralization improves the corrosive activity of aqueous environments relative to unalloyed steels. The presence of carbon dioxide, hydrogen sulfide, or carboxylic acids leads to the oxidation of water-oil mixtures resulting in the increased rate of steel corrosion. We have studied the effectiveness of the synthesized inhibitors based on oil and polyethylene polyamines containing imidazolines. At a temperature of 80 °C, the mixture that contained 200 cm3of a 3 % sodium chloride solution, 800 cm3of oil, and at the concentration of acetic acid of 0.5 and 3.0 g/dm3 at the inhibitor dose of 50 mg/dm3, has reached the degree of protection of steel against corrosion at the level of 90–92 %. Based on a full factorial experiment, the regression equation has been derived that makes it possible to easily enough calculate an optimal dose of the steel corrosion inhibitor in water-oil mixtures. It has been shown that the synthesized inhibitor shows prospects for protecting metals against corrosion both in the mineralized waters containing oil and in the presence of petroleum products containing water

Highlights

The issue related to the chemical resistance of materials and the protection of metals has remained relevant given the permanent corrosion losses by Ukraine’s metal fund, which causes significant material losses in various sectors of industry
The aim of this study is to develop new steel corrosion inhibitors in water-oil mixtures, to assess their effectiveness depending on the composition of an aqueous environment and temperature
We have devised a new method to synthesize alkyl imidazolines based on sunflower oil and polyethylene polyamines in the Octanol solution, which makes it possible to obtain relatively inexpensive highly effective steel corrosion inhibitors in water-oil mixtures

Summary

Introduction

The issue related to the chemical resistance of materials and the protection of metals has remained relevant given the permanent corrosion losses by Ukraine’s metal fund, which causes significant material losses in various sectors of industry. Corrosion accounts for 40‒70 % in the premature destruction of steel structures, which leads to anthropogenic accidents and catastrophes, as well as to the loss of billions of tons of articles. The corrosion-related issues are acute in the chemical, petrochemical, and oil-producing industries [1]. The corrosion rate is much higher at the elevated concentration of carbon dioxide and hydrogen sulfide. Together with the corrosion-active gases dissolved in it, brings the intensive local corrosion damage to steels 20 and St37-2, which are the most common structural materials in the petrochemical and oil and gas extracting industries [2]

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Results

Conclusion