Temperature Effect, Activation Energies and Thermodynamic Adsorption Studies of L-Cysteine Methyl Ester Hydrochloride As Copper Corrosion Inhibitor In Nitric Acid 2M

Abstract

The inhibition of L-Cysteine Methyl Ester Hydrochloride (L-CMEH) on the corrosion of copper in 2M HNO3, was studied by gravimetric method, in the range of temperatures from 303 to 343 K. Results obtained show that L-CMEH acts as inhibitor for copper in HNO3 solution. The inhibition efficiency was found to increase with increase in L-CMEH concentration but decreased with temperature. The inhibition was assumed to occur via adsorption of the L-Cysteine Methyl Ester Hydrochloride on the metal surface. The adsorption of L-CMEH onto the copper surface was found to follow the Langmuir adsorption isotherm. Both kinetic parameters (activation energy, pre-exponential factor, enthalpy of activation and entropy of activation) and thermodynamics of adsorption (enthalpy of adsorption, entropy of adsorption and Gibbs free energy) were calculated and discussed.