Computational modelling and correlation of physical parameters of 1-heptatriacotanol, phytol and 3, 7, 11, 15-tetra methyl-2-hexadecen-1-ol with the corrosion inhibition efficiency of CIW for mild steel in HCl

Abstract

ABSTRACT Aqueous leaves extract of Clerodendrum infortunatum (CIW) was used as inhibitor for mild steel corrosion in 0.5 N HCl. Inhibition efficiency decreases with temperature. The presence of 1-heptatriacotanol, the diterpene alcohols like phytol and 3, 7, 11, 15 tetramethyl-2-hexadecen-1-ol are identified as major constituents through GC-MS analysis of CIW. The electronic properties and inhibition efficiency of these compounds were evaluated using DFT and material studio software. The donor–acceptor type interactions resulting from the migration of lone pair of electrons of the ‘O’ atom of these molecules to the vacant ‘d’ orbital of the metal is evident from these calculations. The reduction in the double-layer capacitance with the incremental addition of CIW is noticed. CIW offers mixed inhibition with anodic predominance. CIW forms a multimolecular layer on the metal surface obeying the Temkin isotherm model. Surface perturbations were followed qualitatively by SEM, stereomicroscope and XPS.