Sodium molybdate as a corrosion inhibitor for aluminium in H3PO4 solution

The inhibition effect of sodium molybdate (Na2MoO4) on the corrosion of aluminium in 1.0 M H3PO4 solution was studied by weight loss, potentiodynamic polarisation curves and electrochemical impedance spectroscopy (EIS) methods. The results show that Na2MoO4 is a good inhibitor, and the inhibition efficiency obtained by three methods is higher than 84% at 20 mM. The adsorption of Na2MoO4 obeys Freundlich isotherm at lower concentrations (1-7 mM), while Langmuir isotherm at higher concentrations (7-20 mM). Polarisation curves indicate that Na2MoO4 acts as an anodic inhibitor. EIS spectra exhibit three loops (two capacitive loops and one inductive loop). (C) 2011 Elsevier Ltd. All rights reserved.