The effects of structural variation in some isoxazolidines on the corrosion inhibition of carbon steel in 0.5 M sulfuric acid

Abstract

PurposeThe aim is to demonstrate corrosion inhibition capabilities of several isoxazolidines, containing hydrophobic substituents and having varying degree of steric congestion around nitrogen.Design/methodology/approachA number of isoxazolidines were prepared. Corrosion inhibition efficiencies of these organic compounds were determined by gravimetric and electrochemical methods, using carbon steel as the substrate metal and 0.5 M H2SO4 at 40‐70°C as the corrosive environment. Concentration of inhibitor was varied between 5 and 400 ppm.FindingsIncrease in steric congestion around the nitrogen centre and hydrophobic chain lengths as well as increase in temperature (in the presence of the inhibitor in the higher concentration range 100‐400 ppm) were found to increase the corrosion inhibition efficiency of the isoxazolidines. Electrochemical measurements corroborated these results. Thermodynamic parameters (ΔGads0,ΔHads0,ΔSads0) for the adsorption process and kinetic parameters for the metal dissolution (or hydrogen evolution) reaction were determined.Originality/valueThis is the first time the corrosion inhibition characteristics of isoxazolidines, an important class of readily accessible compounds, have been evaluated in H2SO4 medium.