Elucidating the inhibition behaviour of Pterocarpussantalinoides leaves extract on mild steel corrosion in H2SO4 solution–GC-MS, FTIR, SEM, Experimental and computational approach

The drift towards the application of green inhibitors to mitigate acid corrosion of steel continues to encourage research into developing highly effective inhibitors derived from crude extracts of plant parts. The study investigates the inhibition behaviour of ethanol extract of Pterocarpussantalinoides (PS) against the corrosion of mild steel in 0.25 M H2SO4. Weight loss measurements showed that 1000 mg/l PS protected the steel with 88 % efficiency after 24 h immersion, which decreased to 47 % after 120 h immersion. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements confirmed that PS extract is a mixed-type inhibitor and its adsorption lowers the double layer capacitance and rate of charge transfer at the steel-solution interface. The phenomenon blocks the steel surface damage based on SEM characterization. GC-MS and FTIR characterizations confirm that PS extract contain four major abundant phytoconstituents namely; benzeneacetaldehyde (BA), 2(5H)-furanone (FUR), ethyl 9,12,15-octadecatrienoate (EOD) and linoleic acid ethyl ester (LAEE). Molecular dynamic simulation (MDS) technique confirmed that individual molecules that formed the major parts of the extract contributed effectively in corrosion inhibition process in the order of EOD > LEAA > BA > FUR 

Corrosion inhibition effect of a benzimidazole derivative on heat exchanger tubing materials during acid cleaning of multistage flash desalination plants

A benzimidazole derivative, 2-(2-bromophenyl)-1-methyl-1Hbenzimidazole (2BPB) has been studied as a corrosion inhibitor for Cu-Ni 70/30 and 90/10 alloys in 1 mol/dm3 HCl solution at low and high temperatures using the weight loss, electrochemical (potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), & cyclic voltammetry (CV)), and surface characterization (scanning electron microscopy (SEM) & Fouriertransform infrared spectroscopy (FTIR)) techniques. The effect of immersion time (up to 72 h) and addition of iodide ions on the inhibition efficiency of 2BPB have also been investigated. At low temperature, 1.0 g/L 2BPB inhibits Cu-Ni 70/30 and 90/10 alloys by 88.9 ± 4.8% and 57.5 ± 1.3%, respectively. The performance of 2BPB improves with increase in immersion time and addition of iodide ions but slightly depreciates with rise in temperature. 2BPB acts as a mixed type corrosion inhibitor and adsorbs on the alloys surfaces through physical adsorption mechanism. SEM and FTIR results confirm the adsorption of 2BPB on the alloys surfaces. 2BPB is a potential low toxic candidate for the formulation of acid corrosion inhibitor for Cu-Ni alloys

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

Adsorption and corrosion inhibition characteristics of 2–(chloromethyl) benzimidazole for C1018 carbon steel in a typical sweet corrosion environment: Effect of chloride ion concentration and temperature

Benzimidazole derivatives are emerging as promising corrosion inhibitors for oil and gas application because they exhibit high efficiency and very good environmental profile. Although long alkyl and phenyl chains enhance their efficiency, they also increase their toxicity. Finding benzimidazole derivatives devoid of long hydrocarbon chains and with lower toxicity has become a priority. 2–(chloromethyl)benzimidazole (CMB), with log Po/w = 2.2, has been investigated as a promising low-toxic sweet corrosion inhibitor for C1018 carbon steel in CO2–saturated NaCl solution under static condition using experimental and theoretical approaches. At 25 ◦C, Open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques confirm that CMB is an anodic-type sweet corrosion inhibitor which is able to form a protective layer on the steel surface and provide inhibition efficiency of 97.54% at 10 ppm. The efficiency increased to 98.40% and 98.58% upon increasing the temperature to 40 ◦C and 60 ◦C, respectively but decreased to 96.32% and 94.76% as the salt concentration was raised to 5.0% and 7.0% NaCl, respectively. The latter was attributed to the antagonistic competition between Cl– ions and CMB for anodic adsorption. The CMB–steel interaction is facilitated by the free electrons around N heteroatoms and C = C bonds, based on FTIR analysis and computational calculations. This eventually ameliorates the surface degradation of the steel during the sweet corrosion at 25 and 60 ◦C. CMB performance is highly comparable with reported sweet corrosion inhibitors with higher toxicity values

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