Electrochemical, thermodynamic, surface and theoretical investigation of 2-aminobenzene-1,3-dicarbonitriles as green corrosion inhibitor for aluminum in 0.5 M NaOH

The influence of 2-aminobenzene-1,3-dicarbonitriles derivatives (ABDNs) namely 5'-amino-2,4-dihydroxy-4 ''-methyl-1,1':3',1 ''-terphenyl-4',6'-dicarbonitrile (ABDN-1), 5'-amino-2,2 '',4-trihydroxy-1,1':3',1 ''-terphenyl-4',6'-dicarbonitrile (ABDN-2) and 5'-amino-2,3 '',4-trihydroxy-1,3-methoxy, 1':3',1 ''-terphenyl-4',6'-dicarbonitrile (ABDN-3) on aluminum corrosion in 0.5 M NaOH was investigated using chemical and electrochemical methods. Potentiodynamic polarization study reveals that 2-aminobenzene-1,3-dicarbonitriles were mixed type inhibitors. Adsorption of 2-aminobenzene-1,3-dicarbonitriles on aluminum surface in 0.5 M NaOH follows the Langmuir adsorption isotherm. Adsorption of inhibitors on aluminum surface was studied using SEM and EDX spectroscopy examinations. Quantum chemical calculations support the weight loss and electrochemical observations. (C) 2015 Elsevier B.V. All rights reserved.