Adsorption and corrosion inhibition behavior of vitamin B1 and ascorbic acid on iron B500 in hydrochloric acid

Abstract

In our study, vitamin B1 and ascorbic acid were used as inhibitors for B500 steel in a 1 M HCl acidic medium. The weight loss method was employed to determine the corrosion rate, inhibition efficiency, and surface coverage. Based on the obtained data for both inhibitors, the Langmuir adsorption isotherm was constructed, and the adsorption constant (K_ads) and Gibbs free energy of adsorption (ΔG_ads) were calculated. An increase in the concentration of ascorbic acid reduced the corrosion rate from 0.00608 mm/year in the acidic medium without inhibitor to 0.00184 mm/year in the presence of 1 g/L ascorbic acid. However, it was observed that the values became stable when the concentration reached 0.5 g/L. Increasing the concentration of vitamin B1 gradually reduced the corrosion rate from 0.00608 mm/year to 0.00133 mm/year in the presence of 1 g/L inhibitor. Furthermore, increasing the inhibitor concentration to 1 g/L enhanced the inhibition efficiency to 78.09% for vitamin B1 and 69.79% for ascorbic acid, while the surface coverage reached 0.781 for vitamin B1 and 0.698 for ascorbic acid.