Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents

Mariana Royer (1) , Didier Stien (1) , Jacques Beauchêne (1) , Gaëtan Herbette (2) , John Paul Mc Lean (3) , Anne Thibaut (1) , Bernard Thibaut (1)

1 ECOFOG - Ecologie des forêts de Guyane
2 AMU SPEC - Spectropôle - Aix Marseille Université
3 MAB - Mécanique de l'Arbre et du Bois

A comparative study of 9H-pyrido[3,4-b]indole (norharmane) and 1-methyl-9H-pyrido[3,4-b]indole (harmane) as inhibitors for C38 steel corrosion in 1 M HCl solution at 25 °C was carried out. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques were applied to study the metal corrosion behavior in the absence and presence of different concentrations of these inhibitors. The OCP as a function of time were also established. Cathodic and anodic polarization curves show that norharmane and harmane are a mixed-type inhibitors. Adsorption of indole derivatives on the C38 steel surface, in 1 M HCl solution, follows the Langmuir adsorption isotherm model. The ΔGads values were calculated and discussed. The potential of zero charge (PZC) of the C38 steel in inhibited solution was studied by the EIS method, and a mechanism for the adsorption process was proposed. Raman spectroscopy confirmed that indole molecules strongly adsorbed onto the steel surface. The electronic properties of indole derivates, obtained using the AM1 semi-empirical quantum chemical approach, were correlated with their experimental efficiencies using the linear resistance model (LR).

Keywords: Indole derivatives; Corrosion; Corrosion inhibitor; Raman spectrometry; Impedance; Hydrochloric acid; Corrosion protection; dimensional stability; Eperua falcata; extrac-tives; HPLC; NMR; tropical wood

Domains: Life Sciences [q-bio]

Mariana Royer, Didier Stien, Jacques Beauchêne, Gaëtan Herbette, John Paul Mc Lean, et al.. Extractives of the tropical wood wallaba (Eperua falcata Aubl.) as natural anti-swelling agents. Holzforschung, 2010, 64 (2), pp.211-215. ⟨10.1515/HF.2010.034⟩. ⟨hal-01093227⟩