An experimental and dual computational study using DFT and MD simulations to better understand the adsorption and corrosion-inhibiting properties of N-(3-(4-Methoxyphenyl) isoxazol-5-yl) methyl saccharin for C38 Steel in acidic medium

This study evaluates the anti-corrosion efficacy of a novel synthetic organic non-toxic inhibitor were characterized using Fourier-transform infrared spectroscopy (FTIR), known as a saccharin derivative linked to isoxazole with the name N-(3-(4-Methoxyphenyl) isoxazol-5-yl) methyl saccharin (MIMS), against C38 steel corrosion in 1 M hydrochloric acid (HCl) milieu using both computational and experimental analyses. MIMS 's toxicity and solubility were properly examined. The kinetic corrosion characteristics were measured using gravimetric weight loss (WL) and electrochemical testing (electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP). WL investigations were conducted at various concentrations, and at 1 mM, the inhibitory efficiency (IEWL) was 94.54 %. According to PDP and EIS data, MIMS had a considerable inhibitory efficiency (eta PDP/eta EIS) with an ideal corrosion current density (icorr) of 21.7 mu A/cm2, creating a eta PDP of 94.29 %. The charge transfer resistance (Rtc) was measured as 518.7 Omega cm2, with a eta EIS of 92.35 % at 1 mM. PDP analysis showed that MIMS acting as a mixed-type inhibitor. The effects of temperature on the behavior of corrosion with the addition of BTMS were investigated between 293 K and 328 K. According to the Langmuir isotherm model's Gibbs free energy, MIMS molecule primarily prevent acid assault by physisorption and chemisorption. Micrographs of Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX), and Atomic Force Microscopy (AFM) demonstrated that the MIMS developed a protective adsorption layer on the C38 steel surface. DFT investigations show that both the neutral and protonated forms of MIMS interact significantly with metallic surfaces through lone pair electrons on heteroatoms (S, N, and O) and it-electrons inside conjugated structures. Furthermore, molecular dynamics (MD) simulations were employed to examine the interaction behavior of neutral and protonated MIMS with Fe (110) and Fe2O3 (110) surfaces in an aqueous solution. The results demonstrate the strong adhesion of MIMS to both Fe (110) and Fe2O3 (110) surfaces in the corrosive medium. The findings from MD/DFT calculations align well with the experimental results.