Adsorption and characterization of anisaldehyde as corrosion inhibitor for aluminium corrosion in hydrochloric acidic environment

Abstract

The inhibitive, thermodynamic and adsorptive properties of anisaldehyde for the aluminium corrosion in 1.4 M HCl solution has been investigated using weight loss method and characterized by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) analysis. The aldehyde was found to be good inhibitor for aluminium corrosion in HCl. As the temperature increases, the inhibition efficiency of the inhibitor decreases, but increases with increasing inhibitor concentration. The activation energy was 25.28 kJ mol-1 for the empty acid solution, which increased to 35.34 kJ mol-1 in addition to the 0.1 M inhibitor. The evaluated enthalpy of adsorption (ΔHads ) gave positive values which indicating that the heat of adsorption process on the surface of the aluminum is endothermic. Negative values of the entropy adsorption (ΔSads) indicate that the complex implemented in the rate-determining step is an association, not a dissociation. Evaluated values of free energy of adsorption (ΔGads) were all negative, implying spontaneity of the process and were around and less than -20 kJ/mol, indicative of physisorption of the adsorption process. The adsorption was found to obey Langmuir, Temkin, Frumkin, Freundlich and El-Awady isotherms.