Evaluation of corrosion inhibitors in acid medium

Abstract

Purpose – The purpose of this paper is to evaluate the corrosion inhibitor performance in acid medium through the determination of Fe2+ ions present based on reaction kinetics of steel with the acid. The use of corrosion inhibitors has been an excellent technique for protecting carbon steel pipes acidizing operations in oil wells. The inhibitor forms a chemical barrier on the metal surface that prevents or reduces attack by the acidic media. Design/methodology/approach – The experimental study provides a methodology to evaluate the performance of corrosion inhibitors in an acid medium, preferentially of concentrated hydrochloric acid. The process consists essentially of total immersion coupons of carbon steel, with continuous stirring, controlled temperature and quantitative determinations of iron ions from the dissolution of steel. The additions of commercial corrosion inhibitor base of ethoxylated amines of high molecular weight in an acid medium showed excellent performance at a temperature ranging from 25 to 45°C. Findings – This paper presents the mechanisms of protection, performance graphs and calculations of the activation energies of the addition of corrosion inhibitors in an acidic medium. Originality/value – The originality of this essay is to evaluate and correlate the performance of corrosion inhibitors with the activation energy in experimental conditions.