Inhibition of mild steel corrosion using Magnolia kobus extract in sulphuric acid medium

Magnolia kobus DC. (M. kobus), a prominent Southeast Asian flowering plant species, was investigated for its inhibition efficiency against mild steel corrosion in 1 M H2SO4. The extract (M. kobus) was identified to have 145.80 mu g/g of myricetin and 102.32 mu g/g syringic acid as prominent components, with a total phenolic content (TPC) of 95.26 mg/g and a total flavonoid content (TFC) of 25.38 mg/g. The mass-loss measurements showed that 500 ppm of M. kobus extract was able to inhibit corrosion, with an efficiency of 95.01% at 303 +/- 1 K. Reduction of dissolved iron content in the inhibited solution than in the inhibitor free solution observed in Atomic Adsorption Spectroscopy (AAS) revealed the corrosion mitigating effect of inhibitor on mild steel. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM) analysis of the protected and unprotected mild steel samples indicate adsorption of M. Kobus on the electrode surface. UV-vis and FT-IR studies complement the above results. The electrochemical studies indicated that M. kobus functioned as a mixed-type indicator and myricetin along with other plant components present in the plant extract contributed to the inhibition process.