Evaluation of corrosion inhibition effect of glycerol stearate on aluminium metal by electrochemical techniques
Thabo Pesha, Vusimuzi L. Mulaudzi, Mduduzi L. Cele, Mmaphefo P. Mothapo, Fulufhelo Ratshisindi
Abstract
The inhibitory effect of glycerol stearate (GS) on aluminium (Al) metal was examined utilizing weight loss, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) in hydrochloric acid (HCl) solution. Gravimetric analysis, PDP, and impedance spectroscopy were used to calculate the rate of corrosion (EIS). Gravimetric measurement and electrochemical methods both demonstrated that when the inhibitor concentration increased, the corrosion rate decreased. PDP and EIS inhibition effectiveness was best at 50 × 10-5 mol. L-1 glycerol stearate concentration,with 81.1% and 86.1%, respectively. The differences in corrosion potential (Ecorr) values between the blank and inhibitor (GS) concentrations revealed that glycerol stearate acted as a mixed type of corrosion inhibitor. The inhibitors' adsorption on the aluminium surface followed the Langmuir isotherm model. Fourier transform infrared spectroscopy (FTIR) indicated the existence of an adsorption coating on the surface of the aluminium metal. SEM pictures of aluminium demonstrated decreased inhomogeneities in the presence of glycerol stearate.