Reaction between Zinc and Hydrochloric Acid in Solutions Containing Alkyltrimethylammonium Bromide C_nTAB (n = 8, 10, and 12) Cationic Surfactants: Influence of Surfactant Chain Length

Abstract

The influence of CnTAB cationic surfactant chain length (n = 8, 10, and 12) on the reaction rate of zinc powder and 0.1 M HCl hydrochloric acid in aqueous solutions was determined at room temperature. Solutions of single surfactants consisting of dodecyl, decyl, and octyl‐trimethyl‐ammonium bromide surfactants CnTAB were prepared at room temperature. From the surface tension and conductivity measurements, the critical micelle concentration (CMC) values of the three surfactants were obtained in the presence and absence of the acid. No significant change was observed for CMC values in pure water and in 0.01 M HCl. Adsorption of CnTAB surfactants onto 1% wt./vol zinc (in powder form), using surface tension measurements, was then investigated. The adsorption tendency of CnTAB surfactants onto zinc powder followed the order: C8TAB > C10TAB > C12TAB. The role of surfactants in the reaction rate between zinc powder and 0.1 M M HCl was then investigated using conductivity measurements. A significant difference in the reaction rate was found depending on the surfactant chain length. Reaction times of 3830, 4963, 14,172, and 20,053 s were found for the zinc reaction with (0.1 M HCl), (0.1 M HCl + 40 mM C8TAB), (0.1 M HCl + 40 mM C10TAB), and (0.1 M HCl + 40 mM C12TAB), respectively, suggesting a significant dependency of the reaction rate on the CnTAB chain length. Finally, some corrosion parameters such as the corrosion rate, corrosion inhibition efficiency, and their dependency on CnTAB chain length were presented and discussed.