Optimization for Corrosion Inhibition of Steel in Hydrochloric Acid by DHOT as a Novel Corrosion Inhibitor

The effectiveness of 3-((dicyclohexyl amino)methyl)-5-(4((2-hydroxy benzylidene)amino phenyl)-1,3,4-oxadiazole-2(3H)-thione (DHOT)) as a corrosion inhibitor for mild steel in 1 M HCl was examined using the weight loss method at various temperatures and DHOT concentrations, both in the presence and absence of the inhibitor. For experimental design, a Doehlert experimental design (DED) was employed. A polynomial equation, which is second-order with primary, quadratic, and interaction effects, was suggested and optimized. The Levenberg‒Marquardt approach was used for forecasting multiple coefficients using statistical non-linear regression analysis. The concentration of the inhibitor showed a significantly positive effect as it reduced the corrosion rate, while temperature showed a negative effect. The optimal corrosion rate conditions in the presence of DHOT were 6.6802 gmd at 47.6°C acidic solution temperature and 112.06 ppm DHOT concentration. With these optimal conditions, an inhibition efficiency of 98.9% was obtained.