Organic Corrosion Inhibitors

Abstract

Organic corrosion inhibitors are preferred due to its environmental friendly and effectiveness at a wide range of temperatures. The efficiency of an organic inhibitor depends on the size of the organic molecule, aromaticity, type, and number of bonding atoms or groups in the molecule (either π or σ), nature and surface charge, the distribution of charge in the molecule, and type of aggressive media. The presence of polar functional groups with S, O, or N atoms in the molecule, heterocyclic compounds and pi electrons present in the molecule also increases the efficiency of these organic corrosion inhibitors. The use of computational chemistry such as density functional theory (DFT), molecular dynamic simulation (MD), Monte Carlo (MC) simulations, and quantitative structure-activity relationship (QSAR) modeling has been applied for study of corrosion inhibition properties of organic compounds. This chapter will explain about theoretical and computational study of organic compounds as corrosion inhibitors.

Assessment of the Inhibitory Efficacy of a Thiazole Derivative as an Efficient Corrosion Inhibitor for Augmenting the Resistance of MS in Acidic Environments

“…Thus, in the presence of HMDBT, the following mechanism operates F e + n H 2 normalO ↔ F e false( H 2 normalO false) n a d s F e false( H 2 normalO false) n a d s + 2 normalC l − ↔ F e false[ false( H 2 normalO false) n false( normalC normall false) 2 − false] normala normald normals F e false[ false( H 2 normalO false) n false( normalC normall false) 2 − false] normala normald normals + H M D B T H + ↔ F e false[ false( H 2 normalO false) n …”

“…Thus, in the presence of HMDBT, the following mechanism operates. 66 + n Fe H O Fe(H O) The HMDBTH + species may affect the cathodic reaction. In acid solution, the cathodic hydrogen evolution reaction may be given as follows…”

Current Overview of Corrosion Inhibition of API Steel in Different Environments

“…Their mechanism is based, generally, on competition against water molecules and aggressive ions for available sites on the steel surface. This phenomenon takes place through adsorption mechanisms by electrostatic interactions (physisorption) or by sharing electrons and forming chemical bonds between the CI molecules and the metal (chemisorption) through heteroatoms such as O, N, P, or S. 18 During the last years, environmental and health risks associated with the use of synthetic inorganic and organic inhibitors have prompted the growing necessity of developing "green" CIs (e.g., based on plant extracts, biopolymers, or carbohydrates) capable of offering maximal metal protection with minimal impact on human beings and nature. The requisites for a chemical product to be approved as green CI have been established by legislative bodies like the Paris Commission (PARCOM) and the Registration, Evaluation, Authorization, and Restriction of Chemicals (REACH), which have established that green CIs must be nonbioaccumulative, biodegradable, and with zero or very low marine toxicity level.…”

“…Their mechanism is based, generally, on competition against water molecules and aggressive ions for available sites on the steel surface. This phenomenon takes place through adsorption mechanisms by electrostatic interactions (physisorption) or by sharing electrons and forming chemical bonds between the CI molecules and the metal (chemisorption) through heteroatoms such as O, N, P, or S. 18 …”