Adenosine as corrosion inhibitor for mild steel in hydrochloric acid solution

(2 R ,3 R ,4 S ,5 R )-2-(6-amino-9 H -purin-9-yl)-5-(hydroxymethyl)oxolane-3,4-diol (adenosine) is an identified component present in agarwood leaf extract. The corrosion inhibition activity of adenosine on mild steel in 1 mol dm −3 HCl solution was tested based on the weight loss method and electrochemical methods such as electrochemical impedance spectroscopy and potentiodynamic polarization measurements. Adenosine was found to have inhibition efficiency of 78.88 % at concentration of 1 × 10 −3 mol dm −3 by the weight loss study. In the electrochemical studies, adenosine was shown to be a mixed-type inhibitor that inhibits both the anodic and cathodic reaction. The corrosion inhibition effect was observed to be weakened in hydrodynamic condition. Adenosine was shown to adsorb by mixed-type adsorption (via a physisorption and chemisorption process) based on the calculated Gibbs free energy. The surface morphology of mild steel in 1 mol dm −3 HCl with adenosine showed improvement compared with mild steel in 1 mol dm −3 HCl without adenosine.