Investigation of Vitamin B12 as a corrosion inhibitor for mild steel in HCl solution through gravimetric and electrochemical studies

Abstract

Now a days green corrosion inhibitors are highly in demand to mitigate corrosion of metal and alloys due to their non-toxicity as well as the absence of heavy metal and toxic compounds in comparison to the organic corrosion inhibitors. Since in the past research conducted on vitamin B12 as a corrosion inhibitor, the study of thermodynamic and kinetic parameters was lacking, the present work is focussed on the temperature dependence of corrosion on Vit B12(Vitamin B12) for the mild steel surface which is an influencing parameter in the present day to day industrial problems. There is a desirable need for efficient inhibitors which work well in high temperatures too. So the present study consciously restricts itself to Vit B12, a naturally occurring corrosion inhibitor. VitB12 is a water-soluble vitamin and also called cobalamin. It is an ecofriendly organometallic compound, has many adsorption sites, and is thus a promising candidate for corrosion retardation. The Potentio-dynamic Polarisation and Electrochemical Impedance Spectroscopy (EIS) are the two techniques that have been used in the analysis of the corrosion inhibition efficiency of Vit B12. It has been observed that the addition of inhibitor Vit B12, shows an enhancement in the Rct (charge transfer resistance) and a decrease in the capacitance layer Cdl value, which indicates the formation of a protective layer over the mild steel surface. The study of thermodynamic and kinetic parameters of the inhibitor adsorption over the mild steel was performed through temperature study. The surface morphology in the absence and presence of Vit B12 on the mild steel was analyzed by FE-SEM where the smooth surface is visible in the presence of inhibitor which shows the protective behavior of Vit B12.