Bis(2-hydroxyethyl) ammonium dodecanoate and its constituents as inhibitors for Al corrosion and H2 production in acid medium

Abstract

2-(2-Hydroxyethylamino) ethanol (EA), dodecanoic acid (DA), and a freshly prepared ionic liquid named bis(2-hydroxyethyl) ammonium dodecanoate (ADD) were exercised as mitigators towards the corrosion of aluminum and the production of hydrogen in 2.0 M HCl. The study was performed by gravimetry, gasometry, potential-time measurements, and electrochemical methods. The examined concentration range of such inhibitors was varied between 5×10-6M and 5×10-3M. The amount of generated hydrogen is enhanced with temperature and lowered by increasing the concentration of the organic additive. Galvanostatic studies indicated that the utilized organic materials are effective inhibitors of a mixed type. The inhibition efficacy was found to increase with more additions of inhibitors and is lowered by temperature. ADD is the more effective inhibitor with a protective efficacy of 95.2% at 0.005 M and 298 K. The computed values of ΔGoads vary between – 35.48 and -35.00 kJ/mol depending on the type of the organic compound and temperature that confirms the existence of a physical adsorption mechanism. The lowering in the Kads values with T confirms the escaping of several adsorbed organic particles from the contact metal interface. The thermodynamic adsorption functions, ΔG°ads, and Kads confirmed the spontaneous adsorption process, i.e., physical- and chemisorption mechanisms.