Assessing the efficiency of danacid as corrosion inhibitor for aluminium in HCl medium: Experimental, theoretical and optimization studies

The present study examined the corrosion protection of aluminium in 1M HCl by deploying expired danacid, with techniques such as gravimetric, electrochemical, and density functional theory (DFT). Inhibitor characterization was executed with Fourier transform infrared (FTIR) spectroscopy and gas chromatography mass spectrometry (GC-MS), which was supplemented by optimization of parameters with response surface methodology. The results of gravimetric study indicates that the inhibition efficiency (IE) rose with rise in danacid concentration and reduced with rise in temperature. FTIR results shows the presence of heteroatoms in the inhibitor while further analysis by GC-MS showed the presence of heteroatom-carrying compounds such as menthyl acetate, eicosyl vinyl ester, carbonic acid, dotriacontane, n-hexadecanoic acid, among others. The activation energy value obtained from this work suggest that the inhibitor molecule's adsorption on the surface of aluminium follows physical adsorption mechanism. Potentiodynamic polarization (PDP) results portrays the inhibitor as a mixed-type while the results of electrochemical impedance spectroscopy (EIS) tests gave an inhibition efficiency of 95.05 %. RSM results show optimum inhibition efficiency of 93.57 % while artificial neural network (ANN) gave improved predicted values. The DFT results further show that the danacid molecules could effectively inhibit alumina corrosion in aggressive media. Hence, danacid proved to be a viable inhibitor for aluminium corrosion.