Synthesis, characterization and evaluation of a novel thiazolidinone derivative as a corrosion inhibitor for C38 steel in 1 M HCl medium: experimental and DFT analysis

Abstract

To explore the corrosion behavior of carbon steel (C38) in acidic environments, both experimental and computational methods were employed to evaluate the newly synthesized thiazolidinone product, 2-((3,5,5-trimethylcyclohex-2-en-1-ylidene)hydrazono)thiazolidinone (Isophoron-Thiazolidinone IT), as a corrosion inhibitor for C38 steel in 1 M HCl solution. Characterization techniques, including IR, NMR, spectroscopy, and MS, confirmed the successful synthesis of IT with a yield of 81 %. Experimental tests, including weight loss measurements (WL), EIS, and PDP, demonstrated that IT acts as a mixed-type inhibitor, achieving a peak inhibition efficiency of 96.56 % under optimal conditions (5 × 10⁻³ mol L⁻¹ at 298 K). These results were confirmed through surface analysis using Scanning Electron Microscopy (SEM), which showed that IT molecule adsorb onto the C38 surface, creating a protective layer that prevents corrosion and reduces oxidation. The adsorption of IT on the C38 surface followed the Langmuir adsorption isotherm, indicating a combination of physical and chemical adsorption processes, leading to the formation of a dense, uniform protective film. Computational studies using DFT supported these experimental observations, identifying reactive centers in IT and confirming its efficacy as a corrosion inhibitor.