On the influence of hydrocarbons solvents on the inhibition efficiency of some organic corrosion inhibitors: Theoretical and validation studies

Injecting inhibitors into industrial equipment and piping systems is an effective way to control corrosion. Before application of corrosion inhibitors on an industrial scale, small scale laboratory testing is necessary to define the performance of inhibitors in specific corrosive media. To achieve low inhibitor concentrations for the laboratory, the inhibitor often needs to be pre-diluted before addition to the corrosive media by solvents. However, corrosion inhibitors may be affected by the solvents used. In this study, some cases that make the researchers get fake results in inhibitor science have been discussed by investigating ten organic compounds in different states (vacuum and solvents). Three hydrocarbon solvents, acetone, benzene, and diethyl ether, were selected. Inhibition performance can be improved by pre-design and theoretical simulations. The Density Functional Theory (DFT) was used in this study. Some physical values were used to find a link between the calculated quantum chemical parameters and the effectiveness of inhibition. The theoretical outcomes were confirmed via experimental tests. The corrosion of aluminum in 1 M HCl in the absence and presence of three hydrocarbon solvents was evaluated. Electrochemical measurements were used to estimate the corrosion parameters. It was found that each solvent affected the corrosion rates. Inhibition efficiencies ranged from 31.43 to 81.42 %. The maximum effect was related to acetone. Furthermore, SEM and AFM techniques were used to determine the effects of solvents. Theoretical and experimental results proved that the solvents used with inhibitors produced fake values of inhibitor efficiency.