The Kinetics of Dissolution and Inhibitor Adsorption for Mild Steel in Hcl Solutions

E. A. Noor and A. H. Al-Moubaraki

Department of Chemistry, Girls College of Education, P. O. Box 108866, Jeddah 21351, (Kingdom of Saudi Arabia)

The kinetics of mild steel dissolution and 1-methyl-4[4'-(x) styryl] pyridinium iodides (x:-H, CH3 and -OCH3) adsorption on mild steel surface in 1.5 M HCl were investigated by weight loss measurements. The results indicate that the dissolution rate in absence and presence of 1.0 x 10-4 M of inhibitors is of the first order and hence depends on chloride ion activity. On the other hand, the kinetics of inhibitors adsorption on mild steel were estimated by fitting the experimental data to Temkin adsorption isotherm. The obtained adsorption rate constants were several order of magnitude higher than that for the desorption process. The influence of substituents type on the adsorption process was discussed.

Mild steel; Dissolution; Inhibitors; Adsorption; Kinetics