Understanding the Adsorption of Quinoxaline Derivatives as Corrosion Inhibitors for Mild Steel in Acidic Medium: Experimental, Theoretical and Molecular Dynamic Simulation Studies

Abstract

The anti-corrosive properties of (E)-3-styrylquinoxalin-2(1H)-one (STQ), (E)-1-benzyl-3-(4-methoxystyryl) quinoxalin-2(1H)-one (BMQ) and (E)-3-(2-(furan-2-yl) vinyl) quinoxalin-2(1H)-one (FVQ) were analyzed by different techniques such as: potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), weight loss (WL) and molecular modeling by DFT method and Monte Carlo simulation studies. All quinoxaline derivatives showed appreciable inhibition efficiency. Among the quinoxaline derivatives studied, BMQ exhibited the best inhibition efficiency. The results from the experimental and theoretical investigations show that the order of inhibition efficiency by the quinoxaline derivatives follow the order BMQ > FVQ> STQ. The experimental results suggest that the three tested inhibitors function as mixed-type compounds and the inhibition efficiency increases with the increase in inhibitor concentration and decreased with temperature. Adsorption of the three compounds on mild steel (MS) surface obeys Langmuir's isotherm model. The theoretical study by DFT method, Monte Carlo simulation and radial distribution function (RDF) provided strong evidence that the inhibition efficiency of quinoxaline derivatives is due to their ability to adsorb strongly at the MS surfaces, which is supportive of the obtained experimental results.

Pyrazine Derivatives as Green Corrosion Inhibitors

“…Similarly, SEM microphotographs images shown in Fig. 4 reveals that in the pure acidic solution metal surface corroded badly while applying inhibitor less pitch and damage seen onto metal surface [47]. I.B.…”

“…Three Pyrado [2,3-b] pyrazine derivative (P1) proved as efficiency corrosion inhibitor showing 93% IE at 10 -3 concentration as per EIS analysis [46]. Three Quinoxaline derivative namely STQ, BMQ and FVQ studied by various techniques like EIS, DFT, PDP as corrosion inhibitor for the mild steel / 1M HCl system in which their inhibition efficiency follow the order of BMQ (95.07 %) > FQV (93.74%) > STP (90.92%) [47]. Two Pyrazine derivative namely GP2 and GP3 applied for corrosion inhibitor for C38 steel (1HCl), in which GP3 shows 91.83 % inhibition efficiency and GP2 shows 83.90% inhibition efficiency according to gravimetric analysis at their optimum concentration of 1X10-3 M concentration [48].…”

Comparative Computational Study of L-Amino Acids as Green Corrosion Inhibitors for Mild Steel

“…A typical profile of searching for energetically favorable states by the simulating annealing method for the total energy, average total energy, van der Waals energy, electrostatic energy, and intramolecular energy for Thr/Fe (100) surface was obtained by optimizing the entire system (Figure 3). The behavior of the energy characteristics in Figure 3 is typical for the process of optimizing the energy of an organic molecule on a metal surface in the gas phase [59,62]. The transition of the system to an equilibrium state is observed after a series of first cycles of the simulating annealing algorithm to search for the global minimum of the system.…”

“…It is widely used to research the adsorption behavior of organic molecules on the surface of metals [45][46][47], including amino acids [27,48,57,58]. It has been displayed in a number of works that the estimation of the affinity of organic molecules with metal surfaces, carried out using the COMPASS force field, is consistent with the experimental data [47,59,60]. The optimization of the structure of L-amino acids on the Fe (100) surface was determined in accordance with the following criteria: energy (2 × 10 −5 kcal/mol); force (10 −3 kcal/mol•Å); displacement (10 −5 Å).…”