Synthesis, characterisation and corrosion inhibition screening on 2-chloroacetophenone 4-ethyl-3-thiosemicarbazone: morphology, weight loss and DFT studies

Mild steel is often used as a construction material in the industry because of its relatively low price. However, due to its low corrosion resistance, some form of a protective film should be applied to prevent it from rusting in the corrosive environment. Thiosemicarbazone is one of the Schiff base ligands that can inhibit corrosion due to the presence of electronegative atoms such as N, S, and pi electrons that can cause an efficient adsorption on the mild steel surface. This research aims to synthesise of 2-chloroacetophenone 4-ethyl-3-thiosemicarbazone (2ClAcTSC) and the structure was confirmed using an elemental analyser, UV-Vis, NMR and ATR-FTIR. The inhibitive effects of 2ClAcTSC were studied on mild steel in 1 M HCl and H2SO4 by using the weight loss method and Scanning Electron Microscopy (SEM). It was found that the 2ClAcTSC has better effectiveness in HCl rather than H2SO4 solution. Moreover, the inhibition efficiency increases as the inhibitor concentration increases. The SEM results verified that the inhibitor had been adsorbed on the mild steel surface to form a protective layer. Density Functional Theory (DFT) computations are performed to correlate inhibitor efficiency with intrinsic molecular parameters. The study revealed that the results obtained are consistent with the experimental data reported.

Automated summary

This study synthesized a new thiosemicarbazone compound, 2-chloroacetophenone 4-ethyl-3-thiosemicarbazone (2ClAcTSC), and found that it exhibited better inhibition effects on mild steel in hydrochloric acid solution. The inhibitive efficiency increased with higher inhibitor concentrations. Scanning Electron Microscopy results confirmed the adsorption of the inhibitor on the mild steel surface forming a protective layer.