Comparative Investigations of the Corrosion Inhibition Efficiency of a 1-phenyl-2-(1-phenylethylidene)hydrazine and its Analog Against Mild Steel Corrosion in Hydrochloric Acid Solution

he corrosion inhibition performance of 1-phenyl-2-(1-phenylethylidene) hydrazine (PPEH) and 1-(1-(4-methoxyphenyl)ethylidene)-2-phenylhydrazine (MPEH) for mild steel (MS) in (1.0 M) hydrochloric acid was investigated based on weight loss measurements. Conditions that affect the corrosion inhibition efficiency, such as concentration, immersion time, the chemical structure of Schiff bases, and solution temperature, were possessed in the current study. The experimental findings demonstrated that PPEH is less than MPEH. In addition, (0.005 M) PPEH protected the tested surface by (83.8%) at (30 °C), while (0.004 M) MPEH afforded (87.2%) protection. The inhibition efficiencies of PPEH and MPEH are (83.8%) and (95.1%), respectively, at a concentration of (0.005 M) at (5 h), exposure time. The efficiency of corrosion inhibition of MPEH is greater than PPEH in the hydrochloric acid environment due to the electron-donating group (methoxy group) substituted to the paraposition of the phenyl ring of MPEH. The desorption process of both studied inhibitors upon the (MS) surface follows the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) photographs proved the protective layer s formation upon the (MS) surface. Prog. Color Colorants Coat. 15 (2022), 53-63© Institute for Color Science and Technology.