Synergistic effect study of Cetyl Trimethyl Ammonium Bromide with iodide ions at low concentration for mild steel corrosion in 5.0 M HCl medium

Abstract

• CTAB is investigated for anticorrosion of mild steel in 5.0 M HCl. • CTAB is a good inhibitor for MS in 5.0 M HCl at low concentration. • CTAB takes its performance at high temperature and improves with KI. • Inhibition efficiency of CTAB improves with KI, to reach 99.13 %. • SEM/profilometry results confirm the performance of CTAB/KI mixture. The anti-corrosion propriety of cetyltrimethyl ammonium bromide (CTAB) at low concentration for mild steel (MS) corrosion in 5.0 M HCl medium was examined by using mass loss, electrochemical measurements and surface analysis at 293 K. Current- potential measurement indicated that CTAB reacts as cathodic–type inhibitor and its inhibition increases with its concentration to achieve a maximum of 90.43 % at 100 ppm. Additionally, it is obtained also that the adsorption of the CTAB shadows Langmuir isotherm adsorption. So, the effect of temperature showed that CTAB retains its inhibition at high temperature, and acts electrostatic adsorption with endothermic process. On the other hand, the interaction effect of CTAB with KI was investigated. It is shown that the anti-corrosion efficiency of 100 ppm CTAB rises with KI concentration to attain 99.13 % at 100 ppm KI, indicating that its synergistic effect with CTAB. Finally, the SEM micrographs, 3D-profilometry analysis and PZC charge indicated that the mixture molecules form a defensive layer on the MS surface via two modes. The present investigation gives an economic, efficient measure of corrosion control, and provides theoretical guidance for the efficient use of MS and the development of novel corrosion inhibitors. Molecular structure of mixture, three-dimensional optical profiler images, and EIS diagrams for MS in 5.0 M HCl without, and with mixture.