HIBISCUS ROSA-SINENSIS (JASUD) LEAVES EXTRACTS USED AS CORROSION INHIBITORS FOR MILD STEEL IN HYDROCHLORIC ACID

P. S. Desai*

ABSTRACT

To investigate the efficiency of Jasud extract as a corrosion inhibitor for mild steel in Hydrochloric acid (HCl) and to assess the effect of temperature and the inhibition efficiency. The corrosion rates were determined using the gravimetric (weight loss) and Electrochemical techniques. The results obtained in the absence and presence of Jasud extracts were used to calculate the inhibition efficiency (%I), degree of surface coverage and to propose the mechanism of inhibition and type of adsorption. Results obtained showed that inhibition efficiency (%I) increased with the increase in concentration of Jasud extracts and with the increase in temperature. Phenomenon of chemical adsorption was proposed and inhibitor found to obey Langmuir, Flory-Huggins and Freundlich adsorption isotherms. The values of Ea, ΔH°, ΔS° and ΔG° obtained revealed that the adsorption process was spontaneous. Polarization study reveals that the inhibitors functions as a mixed inhibitor. This paper provides new information on the inhibiting characteristics of Jasud leaves extract under the specified conditions. This environmentally friendly inhibitor could find possible applications in metal surface anodising and surface coatings.

Keywords: Corrosion; Mild Steel; Hydrochloric Acid; Jasud leaves extracts, adsorption.