Elucidating the inhibition behavior of Pterocarpus santalinoides leaves extract on mild steel corrosion in H2SO4 solution-GC-MS, FTIR, SEM, Experimental and computational approach

The drift towards the application of green inhibitors to mitigate acid corrosion of steel continues to encourage research into developing highly effective inhibitors derived from crude extracts of plant parts. The study investigates the inhibition behaviour of ethanol extract of Pterocarpus santalinoides (PS) against the corrosion of mild steel in 0.25 M H2SO4. Weight loss measurements showed that 1000 mg/l PS protected the steel with 88 % efficiency after 24 h immersion, which decreased to 47 % after 120 h immersion. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements confirmed that PS extract is a mixed-type inhibitor and its adsorption lowers the double layer capacitance and rate of charge transfer at the steel-solution interface. The phenomenon blocks the steel surface damage based on SEM characterization. GC-MS and FTIR characterizations confirm that PS extract contain four major abundant phytoconstituents namely; benzeneacetaldehyde (BA), 2(5H)-furanone (FUR), ethyl 9,12,15-octadecatrienoate (EOD) and linoleic acid ethyl ester (LAEE). Molecular dynamic simulation (MDS) technique confirmed that individual molecules that formed the major parts of the extract contributed effectively in corrosion inhibition process in the order of EOD > LEAA > BA > FUR