Some Amidics Compounds As Corrosion Inhibitors For Iron In Hydrochloric Acid Medium

摘要

The corrosion inhibition of materials by organic compounds is explained by their adsorption effects. These are described by two main types of interaction, the physical adsorption and chemisorptions. These depend on the charge of the metal, the nature of the chemical structure of the organic product and the electrolyte type [1]. Several organic inhibitors are formed of compounds having at least one functional group as an amide which is considered the active center of chemisorptions [2]. In this work, the corrosion inhibition of mild steel in 0.1 M HCI was studied by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements by the use of amidic compounds such as 1,5-bis (2-hydroxy benzamido)-3-azapentane (HBP), 1,6-bis (2-hydroxy benzamido)-4azahexane (HBH), 1,7-bis (2- hydroxy benzamido)-4-azaheptane (HPE), 1,7-bis(2- hydroxy benzamido)-4-N-methyl azaheptane (HBM) and 1,8-bis (2-hydroxy benzamido)-3,6-diazaoctane (HBO) which are synthesized according to the published procedure [3]. The addition of these compounds acts differently on the kinetic of corrosion process of mild steel in hydrochloric medium. The comparative study indicates that HBP is the appropriate inhibitor. Its inhibition efficiency increases while its concentration increases in solution to reach 98 % at 10~(-3) M. Electrochemical measurements show that both polarization and transfer resistances increase with HBP concentration. The adsorption of HBP on the steel surface followed the Frumkin isotherm model. The results obtained from the various methods are in good agreement.