Corrosion inhibition of X80 steel in simulated acid wash solution using glutathione and its blends: Experimental and theoretical studies

摘要

In the search for eco-friendly, inexpensive and efficient corrosion inhibitors, glutathione (GLT) and of its formulations with some intensifier compounds were investigated as anticorrosion additives in simulated oilfield scale wash solution. Electrochemical and weight loss techniques were used to monitor corrosion process in-situ, while spectroscopic and microscopic methods were used to characterize corrosion products and surfaces. GLT formed physically adsorbed thin protective film on X80 steel surface and affords efficient corrosion protection, especially as its concentration increased. When added to the aggressive acid wash liquor, corrosion rate, corrosion current and double layer capacitance decreased whereas charge transfer resistance increased due to GLT adsorption on steel surface. GLT worked like a mixed type inhibitor greater inhibitive influence on anodic half reaction. Activation energy, enthalpy, entropy and free energy changes of activation were determined using kinetic and thermodynamic models. With the use of quantum chemical (LUMO-HOMO) calculations, FTIR, SEM/EDS and molecular dynamics simulations, O, N and S sites in GLT molecular structure were confirmed as adsorption sites which facilitate formation of visible protective GLT film on the surface. At temperature as high as 363 K, formulation containing 0.01M GLT was 89.2% efficient which competed reasonably with a commercial inhibitor.