Trazodone as an efficient corrosion inhibitor for carbon steel in acidic and neutral chloride-containing media: Facile synthesis, experimental and theoretical evaluations

Abstract Trazodone (TDO, 2-(3-(4-(3-chlorophenyl)piperazin-1-yl)propyl)-[1,2,4]triazolo-[4,3-a]pyridin-3(2H)-one) was synthesized via a facile strategy without using acid-removing agent of strong activity, and its structure was confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopy. The efficient corrosion inhibition of protonated and neutral TDO for 20# carbon steel (C-steel) in the respective acidic and neutral chloride-containing solutions was verified by gravimetric, electrochemical measurements and surface analyses. The inhibition efficiency of TDO for C-steel in 3.5% NaCl solution was moderately higher than that in 0.5 M HCl medium, reaching 93.1% at 298 K with 8 mM concentration. TDO simultaneously inhibited anodic and cathodic reactions with dominantly anodic effect, and prominently elevated interfacial polarization resistance for C-steel in both media. Morphology observations indicated that the appearance of C-steel was improved with reduced surface roughness due to TDO adsorption. The existence of cationic TDO caused by protonation was confirmed in the adsorption layer after immersion in acidic solution by X-ray photoelectron spectroscopy. Adsorption of TDO on C-steel surface in both solutions conformed to Langmuir isotherm. Quantum chemical calculations under dominant solvent model and molecular dynamics simulations were also performed, the outcomes of which were in good correlation with experimental results.