Synthesis and evaluation of some new hydrazones as corrosion inhibitors for mild steel in acidic media

Mild steel corrosion in HCl solution is an example of corrosion in acidic mediums. The ongoing research efforts to develop novel environmentally friendly corrosion inhibitors raise questions regarding their ability to effectively protect steel from corrosion. Herein, a series of experimental studies were conducted to explain the scientific mechanism of adsorption of four hydrazone derivatives (HDZs) namely, 2-((2,3-dimethylphenyl)amino)-N′-((1E,2E)-3-phenylallylidene)benzohydrazide (HDZ1) (E)-2-((2,3-dimethylphenyl)amino)-N′-(4-hydroxybenzylidene)benzohydrazide (HDZ2) (E)-2-((2,3-dimethylphenyl)amino)-N′-(1-phenylethylidene)benzohydrazide (HDZ3) and N′-cyclohexylidene-2-((2,3-dimethylphenyl)amino)benzohydrazide (HDZ4) on mild steel (MS) in 1.0 M HCl using chemical, electrochemical and surface characterization techniques. All results show that the inhibitor molecules form a stable layer on steel surface through chemical and physical interactions. HDZs adsorption onto the steel surface was found to follow Langmuir model. Furthermore, electrochemical results demonstrated that our developed inhibitors act as mixed-type inhibitors, with HDZ1 showing the highest polarization resistance and lowest corrosion current density. X-ray diffraction and scanning electron microscope were used to study corrosion products phases and surface morphology of MS samples. Our findings provide deeper insights into understanding the interaction mechanisms of HDZs with a steel surface and can be helpful to explore novel approaches to mitigate the steel dissolution.