Characterization of eco-friendly inhibitor by AAS, FT-IR and GC-MS for protection of AISI 304 in acidic environment

Acacia senegalensis (AS) stems as green corrosion inhibitor for AISI 304 in 1 M hydrochloric (HCl) acid using both gravimetric and potentiodynamic polarization techniques was investigated. The stems were characterized by quantitative and qualitative analyses, Atomic absorption Spectroscopy (AAS), Fourier Transform Infrared Spectroscopy (FT-IR) and Gas Chromatography-Mass Spectrometry (GC-MS). Substrates before and after corrosion were characterized by scanning electron microscopy (SEM). The inhibitor concentration, time and temperature were varied accordingly. Corrosion rate increased with increase in temperature and decreased with increases in both inhibitor concentrations and time. Inhibition efficiency of 98.30% occurred at the value of 8% v/v and phytochemical results revealed tannins, alkaloids, saponins, flavonoids with their contents, AAS revealed 75% calcium, 16% magnesium, 3.35% manganese, FT-IR and GC–MS revealed some elements (N=C=S, C=N), chemical bonds/functional groups (NH2) etc which were responsible for the protection of AISI 304. Inhibition efficiency obtained suggested the effectiveness of the inhibitor. The green inhibitor acted as mixed-type. The coupons without green inhibitor were rough with severe pits, while surface with green inhibitor was protected. The weight loss, polarization and the characterization were in good agreement with each other.