Vandana Srivastava

N-Methyl-N,N,N-trioctylammonium chloride as a novel and green corrosion inhibitor for mild steel in an acid chloride medium: electrochemical, DFT and MD studies

In the present work, N-methyl-N,N,N-trioctylammonium chloride (Aliquat 336) has been evaluated as a green and novel corrosion inhibitor for mild steel in a 1 M HCl solution using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP) and chemical, spectroscopic (FTIR and UV-visible) methods. The results show that Aliquat 336 is an effective corrosion inhibitor and showed the maximum inhibition efficiency of 94.6% at a very low concentration of 4.95 μM. The results of the EIS study showed that Aliquat 336 inhibits corrosion by an adsorption mechanism. The PDP results revealed that Aliquat 336 is a mixed type inhibitor, which predominantly acts as a cathodic inhibitor. The formation of an inhibitor film on the metal surface was corroborated by atomic force microscopy (AFM). The adsorption of Aliquat 336 on a mild steel surface obeys the Langmuir adsorption isotherm. Quantum chemical calculations (DFT based) and molecular dynamics (MD) simulation studies further corroborated the adsorption and inhibition action of Aliquat 336 on the steel surface.

Chitosan: A macromolecule as green corrosion inhibitor for mild steel in sulfamic acid useful for sugar industry

The present investigation aims at investigation of low cost nontoxic carbohydrate biopolymer chitosan as corrosion inhibitor alone and in combination with KI for mild steel in 1M sulfamic acid medium using gravimetric, electrochemical and surface analysis techniques. It is found that chitosan alone exhibits inhibition efficiency of 73.8% at 200ppm concentration. However, in combination with KI (5ppm), it gave more than 90% inhibition efficiency. The significant increase in the inhibition performance of chitosan has been explained by the synergistic mechanism. The results of Potentiodynamic polarization study shows that chitosan and its blend with KI decreases both anodic and cathodic reactions occurring at mild steel surface in 1M sulfamic acid medium by blocking active sites of the metal and acts as mixed type inhibitor. EIS study reveals that the polarization resistance increases with increase in the concentration of inhibitors which increases charge transfer resistance across the metal/solution interface. The adsorption of chitosan followed the Langmuir adsorption isotherm. The formation of inhibitor film on metal surface was supported by scanning electron microscopy (SEM) and atomic force microscopy (AFM) surface studies.

Microwave-Induced Synthesis of Chitosan Schiff Bases and Their Application as Novel and Green Corrosion Inhibitors: Experimental and Theoretical Approach

Environmentally friendly three chitosan Schiff bases (CSBs) were first time synthesized under microwave irradiation by the reaction of chitosan and aldehydes [benzaldehyde (CSB-1), 4-(dimethylamino)benzaldehyde (CSB-2), and 4-hydroxy-3-methoxybenzaldehyde (CSB-3)] and characterized by IR and NMR spectroscopy. The corrosion inhibition performance of the synthesized inhibitors was studied by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP). The results show that all the Schiff bases (CSBs) act as effective corrosion inhibitors for mild steel in 1 M HCl solution. Among the synthesized Schiff bases, CSB-3 exhibited the maximum inhibition efficiency of 90.65% at a very low concentration of 50 ppm. The EIS results showed that the CSBs inhibit corrosion by the adsorption mechanism. The PDP results show that all the three Schiff bases are mixed-type inhibitors. The formation of inhibitor films on the mild steel surface was supported by scanning electron microscopy/energy dispersive X-ray analysis and Fourier-transform infrared spectroscopy methods. The adsorption of CSBs on the mild steel surface obeys the Langmuir adsorption isotherm. The theoretical studies via density functional theory and molecular dynamics simulation corroborated the experimental results.