Eco-friendly corrosion inhibitor of Q235 carbon steel in 1.0 M HCl by Isatin/Chitosan Schiff base

This study presents the synthesis of an eco-friendly and green Schiff base, namely Isatin-Cs Schiff base corrosion inhibitor for Q235 carbon steel in 1.0 M HCl corrosion solution. Fourier-transformed infrared FT-IR and 1H NMR was utilized to characterize the prepared Isatin-Cs Schiff base corrosion inhibitor. The inhibition performance in 1.0 M HCl solution was investigated via classic weight loss at various temperatures, potentiodynamic polarization (PPD), and electrochemical impedance spectroscopy (EIS). Scanning electron microscopy SEM, X-ray photoelectron spectroscopy XPS, and water contact angle methods are used to analyze the surface morphology of Q235 carbon steel. The polarization measurements indicate that the corrosion inhibitors act as mixed type. Moreover, the weight loss studies show that the efficiency of inhibitor increases with the concentration of inhibitor to reach a maximum efficiency of 88.4 % with 250 ppm at 25 C-degrees. Nevertheless, increasing temperature has negative effect on the efficiency of the Isatin-Cs inhibitor. The Langmuir isotherm Unveil that Isatin-Cs adsorption on Q235 carbon steel is mediated via physi/chemi-sorption. Based on SEM and XPS analyses Isatin-Cs forms stable protective film on Q235 carbon steel. The DFT results complemented the experiments results, both observed the effectiveness of inhibitor adsorption.