2,3-Quinoxalinedione as a novel corrosion inhibitor for mild steel in 1 M HCl

2,3-Quinoxalinedione (QD) was tested as corrosion inhibitor for mild steel in 1 M HCl solution using electrochemical (potentiodynamic polarisation) and non-electrochemical technique (weight loss and UV–vis spectrophotometric measurement). Results of weight loss and Tafel polarisation measurements showed that this compound has fairly good inhibiting properties for steel corrosion in acidic bath, with efficiencies of around 88% at a concentration of 10−3 M. The inhibition is of a mixed anodic–cathodic nature. Langmuir isotherm is found to provide an accurate description of the adsorption behaviour of the investigated compound. Negative value was calculated for the energy of adsorption indicating the spontaneity of the adsorption process. The formation of complex between metal cations and 2,3-quinoxalinedione is also proposed as additional inhibition mechanism of mild steel corrosion.