Corrosion inhibition of AA 5052 aluminium alloy in 0.5 M NaCl solution by different types of honey

The inhibitive action of five different types of honey (oak honey (H1), coniferous honeydew honey (H2), winter savory honey (H3), alder buckthorn honey (H4) and carob tree honey (H5)) were tested as potential corrosion inhibitor of AA 5052 aluminium alloy in 0.5 M NaCl solution. Investigation was performed by electrochemical methods such as linear and potentiodynamic polarization and impedance spectroscopy measurements. The inhibition efficiency was found to increase with increase in honey concentration and inhibition efficiency changes in the following sequence: H3  H5  H4  H2  H1. Results of polarization behaviour have shown that all tested honeys act as mixed type inhibitors with a higher influence on anodic reaction, as expressed in particular for H1 and H2. The adsorption behaviour of investigated inhibitors can be described by the Langmuir adsorption isotherm and the values determined for standard free adsorption energies indicate physical adsorption of organic compounds from honey on the surface of AA 5052 aluminium alloy in NaCl solution.