Adsorption behavior of pH-dependent phytic acid micelles at the copper surface observed by Raman and electrochemistry

As heated at 90 degrees C, phytic acid (PA) molecules in the solution self-organized to form the PA micelles. The size of PA micelles could be tuned by varying pH of the solutions. The adsorption behavior of the different micelles at the copper surface and their corrosion inhibition mechanisms in 0.5 M H-2 SO4 solution were studied by using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and surface-enhanced Raman scattering (SERS) spectroscopy. Raman studies showed that the bigger micelles anchoring on the copper surface via P-27-O-28, P-43-O-42 and P-35-O-36 groups, while the smaller PA micelles formed at pH 9 adsorbed at the surface through P-35-O-36 group. The electrochemical measurements demonstrated that the copper modified with the smaller micelles presented the best inhibition efficiency in 0.5 M H-2 SO4 solution. (C) 2014 Elsevier B.V. All rights reserved.