The inhibition performance of a novel benzenesulfonamide-based benzoxazine compound in the corrosion of X60 carbon steel in an acidizing environment

A benzenesulfonamide-based benzoxazine compound (BSB) was synthesized from sulfamethizole, salicylaldehyde, and paraformaldehyde in a series of reaction steps. The novel phenolic compound was structurally identified by spectroscopic techniques such as nuclear magnetic resonance (1H & 13C-NMR) and Fourier transform infrared spectroscopy. This novel benzoxazine compound possesses some highly electronegative atoms that are responsible for its corrosion inhibition behavior. The corrosion inhibition performance of BSB against X60 steel corrosion in 15% HCl at 25, 40, and 60 °C, which mimics an oil-well acidizing environment, was investigated by weight loss (WL) measurements and electrochemical techniques. The surface chemical compositions of the inhibitor and substrate (before and after corrosion) were examined using energy dispersive X-ray (EDX), and Fourier transform infrared spectroscopy (FTIR) techniques, respectively. Structural analysis was performed on the corroded steel samples, by scanning electron microscopy (SEM), and atomic force microscopy (AFM) measurements. The WL study of BSB at room temperature revealed over 88% inhibition efficiency for its 600 ppm concentration at room temperature and the efficiency slightly increased to 91% at 60 °C. Furthermore, the study suggested adsorption of BSB at a concentration of 600 ppm could involve the chemisorption adsorption mechanism. However, the PDP results at all the studied concentrations revealed BSB to act as a mixed-type inhibitor with a cathodic predominance. The EDS and FTIR analyses confirmed the BSB adsorption to the steel surface to have occurred via interactions between the BSB heteroatoms and the carbon steel surface. Hence, BSB adsorption follows the Langmuir adsorption isotherm.