Pterocarpus santalinoides leaves extract as a sustainable and potent inhibitor for low carbon steel in a simulated pickling medium

The crude extract of Pterocarpus santalinoides leaves (PSLE) extracted using water, ethanol, and methanol as the extraction solvent has been studied as inhibitor for low carbon steel in 1 moL/dm3 HCl solution using electrochemical approaches at 25 �C and 60 �C. The results obtained reveal that, PSLE extract has the capacity to effectively suppress the dissolution of the studied substrate. The inhibition performance of PSLE is a function of concentration, temperature, and extraction solvent. Corrosion inhibition is in the order: ethanolic extract > methanolic extract > aqueous extract. With 0.7 g/L PSLE, inhibition efficiency of >90% has been obtained at 60 �C. Based on calculated values of adsorption parameters and UV–vis results, it is proposed that PSLE molecules chemically interacted with the substrate surface. PSLE extract suppressed both the rate of cathodic and anodic reactions according to the PDP results. However, aqueous PSLE extract inhibited anodic corrosion reactions predominantly while ethanolic and methanolic extracts mainly inhibited the cathodic corrosion reactions. Surface characterization studies via SEM, EDAX, and AFM provide experimental evidence to the claim of interaction and presence of PSLE molecules on the studied substrate surface

Investigation into the adsorption and inhibition properties of sodium octanoate against CO2 corrosion of C1018 carbon steel under static and hydrodynamic conditions

Sodium octanoate (Na-oct), a simple, naturally-abundant, cheap and low-toxic organic molecule has been investigated for its adsorption and inhibition properties against the CO2 corrosion of C1018 carbon steel in 3.5 % NaCl under static (0 rpm) and hydrodynamic conditions (1000 rpm). At open circuit potential (OCP) under static condition, a Langmuir-type adsorption of Na-oct modified the dielectric property of the steel-solution interface by lowering double layer capacitance and increasing resistance to charge transfer, based on electrochemical impedance spectroscopy (EIS) analysis. Under this condition, potentiodynamic polarization (PDP) analysis showed that Na-oct adsorbed more preferentially on anodic sites of steel surface and impacted ∼96 % inhibition efficiency. Hydrodynamic condition at 1000 rpm caused a Langmuir and Temkin adsorption mechanism and diminished the Na-oct efficiency to ∼86 %. FTIR characterization revealed that the inhibitor adsorption was enabled by its COO– functional group. Computational modeling, using DFT and MDS, confirmed the experimental findings