Interactions at the mild steel acid solution interface in the presence of O-fumaryl-chitosan: Electrochemical and surface studies

•O-fumaryl-chitosan performed as an efficient inhibitor for mild steel in hydrochloric acid.•Electrochemical studies confirmed the inhibitive action of O-fumaryl-chitosan via adsorption.•Formation of adsorbed film is supported by the AFM analysis. The performance of synthesised O-fumaryl-chitosan (OFC) as corrosion inhibitor for mild steel in 1M HCl has been evaluated through various studies. The initial screening by weight loss method revealed the good inhibition efficiency by the inhibitor. Thermodynamic and kinetic parameters have been calculated and discussed. The mode of adsorption is physical in nature and it follows Langmuir adsorption isotherm. Electrochemical measurements supported the inhibition of mild steel by the fumaryl derivative of chitosan. Polarisation studies provided the information that the inhibition is of mixed type. The formation of inhibitor film is assured by surface morphological studies with Scanning electron microscopy (SEM) and Atomic force microscopy (AFM). The mechanism of inhibition is derived from the Fourier-transform infrared (FTIR) spectroscopy and zero charge potential measurement. The adsorbed film is characterised using FTIR and X-ray diffraction studies (XRD).