Corrosion Inhibition of Mild Steel in Different Acid Medium by Using Various Acidic Groups of Organic Compounds

Abstract

Abstract: Benzoic acid, salicylic acid, Anthranilic acid, 2- Nitro benzoic acid, 2- Chlorobenzoic acid compounds containing acidic group as a corrosion inhibitor for carbon steel was investigated. The study revealed that the various group such as (- COOH, OH, Cl and –NO2) containing in organic compounds has an inhibitory action on the corrosion of carbon steel in the investigated medium. Corrosion rate of mild steel was studied using chemical weight loss method at room temperature. This research paper presents use of carboxylic group organic compounds as corrosion inhibitors for metals in 0.1N, 0.01N and 0.001N (HCl, HNO3 and H2SO4) acidic medium. A common mechanism for inhibiting corrosion involves formation of a coating, often a passivation layer, which prevents access of the corrosive substance to the metal. Organic corrosion inhibitors adsorb on the surface to form protective film, which displace water and protect it against deteriorating. Effective organic corrosion inhibitors contain nitrogen, oxygen, sulphur and phosphorus with lone electron pairs as well can contain structural moieties with π-electrons that interact with metal favouring the adsorption process. This review presents mechanisms and monitoring of corrosion, laboratory methods for corrosion study, relationship between structure and efficacy of corrosion inhibitions, theoretical approach to design new inhibitors and some aspects of corrosion. Keywords: Corrosion, Inhibition, carbon steel, Weight loss and acidic group (-COOH, OH, -Cl and –NO2) group containing organic compounds.