Corrosion inhibition of steel in sulphuric acid by aqueous extracts of Rose and Rose water

Abstract

The corrosion inhibition of steel in 2 molar sulphuric acid solution by Rose extract and/or Rose water has been studied at 30°C using chemical (weight loss and hydrogen evolution) and electrochemical (impedance and polarization) measurements. It is found that all methods give consistent results, the inhibition efficiency increases with increasing concentration of the extract, and it shows that rose extract is a better corrosion inhibitor for steel than rose water. The polarization curves indicate that rose extract and rose water act as mixed-type inhibitors. The adsorption of inhibitor on the steel surface is found to obey the Langmuir adsorption isotherm model for rose extract and Freundlich adsorption isotherm for both rose extract and rose water. Thermodynamic data for the adsorption process (K_ads and G°_ads) were calculated and discussed.