Green approach to corrosion inhibition of mild steel in 1 M HCl solutions by Monosaccharides derivatives

Effect of new synthesized monosaccharide derivatives, namely: D-mannose (M1), D-gluconic acid-γ-lactone (M2), D-galactono-γ-lactone (M3), monoacetoneglucose (M4), diacetoneglucose (M5), on mild steel corrosion inhibition in an aerated acidic solution of 1 M HCl was investigated using weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy measurements. The results indicate that the type of inhibition depends on the type of compounds. Impedance measurements showed that the charge transfer resistance increased and double layer capacitance values decreased with inhibitor’s concentration. It is seen that the M2 performed excellently as a corrosion inhibitor which its efficiency reaches 91 % at 10-3 M. Adsorption of M2 molecules on mild steel surface was also studied to examine basic information on the interaction between the inhibitors and the metal surface. It is found that the inhibitor adsorb on the metal surface following the Langmuir isotherm model. The temperature effect on the performance of mild steel in 1 M HCl in the absence and presence of the best compound was studied in the temperature range from 293 to 323 K. Also, some thermodynamic data for the adsorption and dissolution processes are calculated and discussed

Eco-Friendly Tri-Sodium Citrate as Corrosion Inhibitor for Mild Steel in Synthetic Cooling Water System

The influence of an ecofriendly tri-sodium citrate (TSC) on the inhibition of mild steel corrosion in synthetic cooling water was studied by using potentiodynamic polarization (PP), and electrochemical impedance spectroscopy (EIS) measurements. The state of mild steel surface was characterized by scanning microscopy electron (SEM) analysis. It is found that TSC acts as an anodic type inhibitor where its inhibition increases with concentration to reach a maximum of 89 % at 10-3 M. Indeed, the EIS plots revealed that TSC increases the polarization resistance of mild steel confirming the current-potential measurement and indicated that the inhibition efficiency of TSC increase with immersion time until 24 h of immersion. SEM investigation demonstrated that the inhibition of mild steel in corrosive/TSC solution was realized by the TSC molecules adsorption onto mild steel to prevent the dissolution process by blocking the active sites on its surface. Thus, it is shown that the TSC obey to the Langmuir isotherm and it is adsorbed via both physical and chemical adsorption which can explain by potential of zero charge (PZC) technique