Numerical analysis of the inhibition effect of Commiphora myrrha and Cymbopogon nardus plant extracts on low carbon steel corrosion in simulated industrial environment

Abstract

The corrosion inhibition properties of specific concentrations of Commiphora myrrha (CM), Cymbopogon nardus (CN) green chemical compounds and their combined admixture (CMCN) on low carbon steel in dilute H2SO4 and HCl solution was studied by weight loss analysis. Results show CM performed poorly at low concentrations (0.5% − 1.25% CM) with optimal inhibition value of 51.41% compared to CN which performed effectively at all concentrations with inhibition value generally above 85%. Performance of CM and CN compound in HCl solution were generally similar. Both compounds exhibited poor inhibition efficiency below 60% at low concentrations (0.5% − 0.75% concentration). At higher concentrations, their inhibition efficiencies were generally above 70%, with optimal values of 83.05% and 96.07% at 1.5% CM and 1.75% CN concentrations. Admixture of CM and CN inhibitor (CMCN) performed poorly in H2SO4 solution with inhibition value below 60% at all concentrations. This contrast the observation in HCl were it performed effectively at all concentrations with inhibition efficiency generally above 80%. Statistical analysis through ANOVA shows inhibitor concentration is the only statistically relevant variable influencing the performance outputs of the inhibitors with values of 92.29% and 88.48% for CM and CN in H2SO4, and 41.40% and 95.25% in HCl. Values for CMCN are 69.57% and 4.69% in H2SO4 and HCl solution. Standard deviation calculations show 33% and 98% at + 11.93% and + 3.24%% margins of error in H2SO4, and 25%and 53% at + 10.96% and ± 12.62% margins of error in HCl of CM and CN inhibition efficiency are above the 80% effective inhibition threshold value. Values for CMCN are 0% in H2SO4 and 100% in HCl which are above the 80% threshold.