H. Lgaz

Thiosemicarbazide and thiocarbohydrazide functionalized chitosan as ecofriendly corrosion inhibitors for carbon steel in hydrochloric acid solution

Organically functionalized chitosan macromolecules namely Chitosan-Thiosemicarbazide (CS-TS) and Chitosan-Thiocarbohydrazide (CS-TCH) were synthesized and evaluated as new corrosion inhibitors for mild steel corrosion in 1M HCl. The FTIR and 1H NMR studies confirmed the formation of the derivatives. The corrosion tests were performed using weight loss method, electrochemical measurements, surface morphology (AFM), quantum chemical investigation and molecular dynamics simulation methods. The maximum efficiency of 92% was obtained at a concentration as low as 200mgL-1. The inhibitors were found to obey Langmuir adsorption isotherm and exhibited both physical and chemical adsorption. Electrochemical impedance spectroscopy (EIS) results showed an increase in polarization resistance which supported the adsorption of inhibitors on the mild steel surface. Tafel data showed a mixed type behavior with cathodic predominance. The data of quantum chemical calculations and molecular dynamics simulation supported the experimental findings.

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.

Sugar based N,N ′-didodecyl- N,N ′digluconamideethylenediamine gemini surfactant as corrosion inhibitor for mild steel in 3.5% NaCl solution-effect of synergistic KI additive

The inhibitory behaviour of non-ionic sugar based N,N′-didodecyl-N,N′-digluconamideethylenediamine gemini surfactant, designated as Glu(12)-2-Glu(12) on mild steel (MS) corrosion in 3.5% NaCl at 30–60 °C was explored using weight loss, PDP, EIS and SEM/EDAX/AFM techniques. The compound inhibited the corrosion of mild steel in 3.5% NaCl and the extent of inhibition was dependent on concentration and temperature. The inhibiting action of Glu(12)-2-Glu(12) is synergistically enhanced on addition of potassium iodide (KI) at all concentrations and temperatures. The inhibiting formulation comprising of 2.5 × 10−3 mM of Glu(12)-2-Glu(12) and 10 mM of KI exhibits an inhibition efficiency of 96.9% at 60 °C. Quantum chemical calculations and MD simulation were applied to analyze the experimental data and elucidate the adsorption behaviour and inhibition mechanism of inhibitors. MD simulation showed a nearly parallel or flat disposition for Glu(12)-2-Glu(12) molecules on the MS surface providing larger blocking area to prevent the metal surface from corrosion.

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.

Pyrazoline derivatives as possible corrosion inhibitors for mild steel in acidic media: A combined experimental and theoretical approach

Abstract Various experimental and theoretical methods have been employed to study the effectiveness of two pyrazoline derivatives namely, 2-(4-(5-(p-tolyl)-4,5-dihydro-1H-pyrazol-3-yl)phenoxy)acetic acid (P1) and 2-(4-(5-(4-nitrophenyl)-4,5-dihydro-1H-pyrazol-3-yl)phenoxy)acetic acid (P2) as corrosion inhibitors for mild steel in 1.0 M HCl at 303 K. The inhibitors show high inhibition efficiency and their adsorption on mild steel surface was found to obey Langmuir adsorption isotherm. Potentiodynamic polarization results revealed that both compounds behaved as mixed-type inhibitors. The results from electrochemical impedance spectroscopy studies reveal an increase in polarization resistance. Density Functional Theory calculations and molecular dynamic simulations were used to give basic insights into the action mode of inhibitors as well as to substantiate the experimental results. The surface morphology of the mild steel surface was examined using Scanning Electron Microscopy and Atomic Force Microscopy.