MD and DFT computational simulations of Caffeoylquinic derivatives as a bio-corrosion inhibitor from quince extract with experimental investigation of corrosion protection on mild steel in 1M H2SO4

Abstract

The inhibition performance of Quince Extract (Q.E.) at concentrations of 0–1200 ppm on the low carbon steel corrosion in the corrosive media of sulfuric acid (H2SO4) was evaluated by using conventional electrochemical methods (potentiodynamic polarization and impedance spectroscopy). Based on the results, Q.E. displays a mixed-type behavior as an inhibitor. The inhibition efficiency of Q.E. increased with its concentration in the acid solution .The highest performance was observed at the maximum tested concentration (1200 ppm). Using polarization and EIS results, the highest inhibition efficiency of Q.E. was estimated to be 94.5% and 90.7%, respectively. Structural units and functional groups of Q.E. were detected by Fourier transform infrared spectroscopy. This spectroscopy confirmed that the extract contains nitrogen atoms, oxygen atoms, and aromatic rings that are known to have corrosion inhibition effects. The morphology of the specimen's surface after exposure to H2SO4 with and without Q.E. was examined by SEM and AFM techniques. This examination showed substantially lower surface degradation in the low-carbon steel specimens exposed to the acid in the presence of Q.E. The Langmuir isotherm approach was utilized to explain the adsorption of Q.E. onto the low-carbon steel surface. The Gibbs free energy calculated based on this approach (-21.05 kJ-mol−1) confirmed that the Q.E. adsorption onto the steel surface is supposed to involve more physisorption. In addition to the results of molecular simulation and computational chemistry, such as molecular dynamics simulation (MD), density functional theory (DFT), and Monte Carlo for all Caffeoylquinic acid derivatives confirmed that amino acid of quince extracts in an acidic medium (1 M sulfuric acid) adsorbed on compact and energetic iron surfaces mainly surfaces with miller index (110), which are inclined to corrosion and electrochemical reactions, takes place spontaneously.