Gravimetric and electrochemical studies of the control of aluminum deterioration in HCl using Ukpo clay - polyaniline as inhibitor

This study presents the use of Ukpo clay- polyaniline as inhibitor to control deterioration of aluminium in HCl. The substance (inhibitor) was characterized using gas chromatography-mass spectrophotometer. Gravimetric (weight loss) and electrochemical (potentiodynamic polarization and electrochemical impedance spectroscopy) techniques were employed in the corrosion control procedure. Analyses of the experimental results showed that Ukpo clay/polyaniline composite contains chemical constituents (2-cyclopropyl-2-methyl-n-(1-cyclopropylethyl), 2-bromo-4-fluorophenyl ester, bis(2-ethylhexyl) phthalate, piperidine-4-carbonitrile) suited for the deterioration control of Al in HCl. For the gravimetric analysis, the corrosion inhibition process was found to be spontaneous, exothermic, and in agreement with physical adsorption mechanism. The activation energy of inhibition was less than the critical values of 80kJ/mol, and Langmuir adsorption isotherm best described the inhibition procedure. The relationship between inhibition efficiency of Ukpo clay - polyaniline composite and factors of inhibitor concentration, temperature and time is a quadratic model. Electrochemical analysis of the study revealed that Ukpo clay/polyaniline composite acted as mixed-type inhibitor. It inhibited both cathodic and anodic reactions. Adding the inhibitor to the HCl medium enhanced the magnitude of the impedance spectrum, which indicates high inhibiting strength of the inhibitor’s constituents in impeding the invasion of the electrochemical reaction. Thus, Ukpo clay - polyaniline composite should be applied as a viable corrosion inhibitor of aluminium in hydrochloric acid environment.