Corrosion inhibition of mild steel in 1 M HCl by pyrazolone-sulfonamide hybrids: synthesis, characterization, and evaluation.

Carbon steel is widely used in the petroleum industry for pipelines, storage tanks, and equipment due to its mechanical properties, and strength. However, challenges such as environmental conditions and corrosive materials can affect its lifespan and require maintenance and repair. This work aimed to prepare pyrazalone-sulfonamide hybrids, and confirmed by mass spectra, FTIR, H-NMR, and C-NMR. These compounds were examined as mild steel corrosion inhibitors in 1 M HCl solutions at 298-323 K using the gravimetric technique, electrochemical measurements, scanning electronic microscope analysis, and quantum chemical calculations. The values of inhibitory efficiency identified by electrochemical and non-electrochemical techniques exhibit good agreement. At various temperatures and in the 50 to 500 ppm concentration range. During the adsorption process, these substances connect to the Langmuir adsorption isotherm. Some adsorption isotherm and kinetic parameters have been developed and discussed. The metal surface had a thin inhibitory protective layer, according to investigations using energy dispersive X-ray spectroscopy (EDX) and scanning electron microscope (SEM). These findings demonstrated the potential of pyrazolone-sulfonamide as effective organic corrosion inhibitors for carbon steel.