Corrosion protection of mild steel by a new binary inhibitor system in hydrochloric acid solution

In the present study, synergistic effect between polysaccharide (Azadirachta indica gum) and four variously substituted piperidin-4-one derivatives on the corrosion inhibition of mild steel in 1 mol L−1 HCl has been analyzed using weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy. Results of the weight loss measurements clearly reveal that depending on the conformations of the piperidin-4-one derivatives, the concentration of A. indica gum varies to achieve its maximum protection level. Detailed FTIR studies of the surface adsorbed layers of inhibitors have been done to elucidate the origin of the synergistic effect on the co-adsorption and subsequent corrosion inhibition of the mild steel.