Azoisonicotinohydrazide derivative as carbon steel corrosion inhibitor in 1 M H2SO4: potentiostatic, adsorption isotherm and surface studies

The inhibition of carbon steel corrosion in acidic media (1 M, H2SO4) by the new hydrazone derivative, namely N'-((E)-2-hydroxy-5-((E)-phenyldiazenyl)benzylidene)isonicotinohydrazide (AS), in combination with nonionic surfactant (Tween 80) have been investigated by electrochemical method (potentiostatic polarization) and surface analyses (scanning electron microscopy). The obtained results confirmed that the new compound (AS) acts as good carbon steel corrosion inhibitor in 1 M H2SO4. The effect of both concentration of AS and temperature have been studied. The highest recorded inhibition efficiency was 91.02% in the presence of 0.08 mM of AS at 323 K. The studied compound AS was effectively adsorbed on the carbon steel surface and the adsorption process obeys the Langmuir isotherms model with correlation coefficient around 0.92. The adsorption studies proved that the adsorption process is mixed type adsorption, spontaneous and exothermic process. The potentiostatic results indicated that the new corrosion inhibitor (AS) is a mixed type inhibitor with predominant anodic effect. The scanning electron microscope analyses confirmed the good performance of the used corrosion inhibitor (AS), the severe damage of the carbon steel specimen surface caused by the aggressive attack of the acid solution was found to be significantly reduced when treated with the acidic solution in the presence of AS.