Corrosive Inhibitive Study of Stainless Steel in Hydrochloric Acid Using Eco-Friendly Sesmum Indicum Oil

Abstract

The inhibitive and adsorptive properties of Sesmum indicum eco-friendly oil for stainless steel corrosion in hydrochloric acid was investigated using weight loss technique as well as electrochemical technique. The result has proved that the oil is excellent inhibitor for stainless steel in hydrochloric acid. The inhibition efficiency of oil for stainless steel increased with increase the amount of oil. The mechanism of the oil on the surface of stainless steel was found to be spontaneous, exothermic and physical adsorption. The experimental data fitted well to Langmuir adsorption isotherms. Obtained results were justified from the galvanostatic polarization method.

4-Ethylcyclohexanonethiosemicarbazone as Corrosion Inhibitor for Iron Metal in 0.5N Hydrochloric Acid Solutions

“…The values of rate constant are obtained using kinetics first order rate law 23 : log(Wi -ΔW t ) = -( k /2.303) t + logWi (4) In above formula Wi is the starting weight of metal coupon and ΔW t is the weight loss during immersion time t. The value of half life was obtained by the following formula: As far as the inhibition process is concerned it is generally assumed that the adsorption of the inhibitor at the metal surface is the first step of the procedure of inhibition in the presence of the corrosive acid media.Experimental values evaluated for surface coverage (θ) were applied for many isotherm equations related to adsorption like Langmuir, El-Awady, Frumkin, Freundlich and Florry-Huggins.However, the best correlation was obtained using the Langmuir adsorption isotherm model. According to this isotherm, θ is related to the C and equilibrium constant of adsorption K ads , using following equation:…”