Agarose as an Efficient Inhibitor for Aluminium Corrosion in Acidic Medium: An Experimental and Theoretical Study

Abstract

The inhibition efficiency and mechanism of agarose on aluminium corrosion in 1 M HCl, 0.5 M H2SO4 and 0.5 M H3PO4 solutions were studied by means of conventional weight loss method, Tafel polarisation electrochemical impedance spectroscopy and scanning electron microscope. The inhibition efficiency (%IE) was observed to increase with addition of agarose concentration, and it adversely decreases with increasing temperature. Moreover, the maximum inhibition efficiency of ~81% is achieved for agarose concentration of 700 ppm in 1 M HCl. Potentiodynamic polarisation curves showed that agarose acts as a mixed-type inhibitor. The absorption isotherm calculations revealed that interactions of agarose on aluminium surface are physisorption and typically obey the Temkin adsorption isotherm. The quantum chemical calculations reveal that active sites promote the agarose to anchor on aluminium surface due to mostly presence of hydroxyl group.