Synergistic effect of halide ions on improving corrosion inhibition behaviour of benzisothiozole-3-piperizine hydrochloride on mild steel in 0.5 M H2SO4 medium

The synergistic effect of iodide ions and benzisothiozole-3-piperizine hydrochloride (BITP) on corrosion inhibition of mild steel in 0.5 M H2SO4 solution has been studied by both chemical and electrochemical methods. The corrosion performance of BITP in 1.0 M HCl and 0.5 M H2SO4 media was examined and compared. The adsorption of BITP and its combination with iodide ions on mild steel surface followed Langmuir adsorption isotherm via chemisorption mechanism. The calculated values of synergism parameter (S-theta) were found to be greater than unity. This result clearly showed the existence of synergism between iodide ions and BITP molecules. (C) 2010 Elsevier Ltd. All rights reserved.