Effects of turbulent flow on the corrosion inhibition properties of 2‐mercaptobenzimidazole

Abstract

The electrochemical techniques, that is, polarization resistance (Rp) and potentiodynamic polarization curves, were used in order to determine the effect of turbulent flow on the corrosion inhibiting effect of 2‐mercaptobenzimidazole (2‐MBI) on API 5L X52 grade steel samples immersed in a 3% NaCl aqueous solution saturated with CO2 at 60 °C. Turbulent flow conditions were controlled using a rotating cylinder electrode (RCE). An inhibition efficiency of 98% was measured at a concentration of 10 ppm of 2‐MBI at a rotation rate of 5000 rpm. This efficiency value is similar to those efficiency values measured at 25 and 40 ppm 2‐MBI and at the same rotation rate. These observations suggest that as the turbulent flow conditions increase the corrosion inhibiting effect of 2‐MBI is enhanced. 2‐MBI follows a Langmuir adsorption isotherm. The calculated values of adsorption equilibrium constant (Kads) and adsorption free energy ($\Delta G_{{\rm ads}}^{{\rm o}} $) suggest that the adsorption process taking place is chemical. The polarization curves indicate that the 2‐MBI does not modify the electrochemical mechanism of the anodic (Fe dissolution) and cathodic (hydrogen evolution) reactions. It is suggested that 2‐MBI decreases the rate at which these reactions occur, blocking the active sites on the steel surface.

Nitrogen‐based corrosion inhibitor film study using weight loss and electrochemical methods in static and turbulent conditions

“…From Table , it is possible to notice some discrepancies in the results between each method for this condition. However, as was mentioned previously, these differences are described in the literature and are based on the principles of each method, since in the LPR method, the calculated efficiency values shown are representative of only the moment when they were calculated and may not necessarily be correlated with long‐term efficiency values for weight loss …”

“…It was possible to notice that the efficiency values were higher than those obtained at the same temperature in bubble test experiments. According to Olvera‐Martinez et al, this observation is associated with the fact that turbulent flow may promote the diffusion of inhibitor molecules from the bulk solution toward the metal surface, and therefore, depending on the condition, the inhibition effect is enhanced. Figures and show the electrochemical results from RCE in the sweet environment at 40°C and at 70°C, respectively, while Figures and present the results from RCE in the sour environment also at 40°C and at 70°C, respectively.…”

Electrochemical evaluation of cephalothin as corrosion inhibitor for API 5L X52 steel immersed in an acid medium

“…It is therefore mandatory to protect all components built from the corrosive environment. There are various methods for corrosion abatement concerned with diminishing the rate of attack; hence, this work addresses the corrosion inhibitors (Olvera-Martinez et al, 2013). Recent literature leads to establishing that the most effective and efficient inhibitors are the organic compounds comprising p bonds, P, S, N, and O heteroatoms, and inorganic compounds, such as chromate, dichromate and nitrite (S ßahin et al, 2008;Samiento-Bustos et al, 2008).…”

Use of an imidazol synthetized from palm oil as a corrosion inhibitor for a supermartensitic stainless steel in H2S

“…One of the most commonly used practices to fight corrosion is the use of organic inhibitors because they can effectively retard the corrosion of steel through forming a compact barrier film between steel surface and corrosive medium (9)(10)(11)(12). Most organic corrosion inhibitors contain heteroatoms, such as nitrogen, oxygen, phosphorus and sulphur as well as triple bond or aromatic ring, considered as the reaction center for the adsorption process (13)(14)(15) because the heteroatoms can donate their lone electron pairs to the empty d-orbitals of Fe atoms to form the coordinate covalent bonds (16,17). Some of the most frequently used organic inhibitors include amines (10,11), amides (15), imidazole and imidazolines (16,17).…”