Mitigation of hydrogen production on C-steel in HCl solution using a benzylidene compound

Abstract

The mitigation influence of N1-(4-(dimethylamino)benzylidene)-N2-(2-((4-(dimethylamino)benzylidene)amino)ethyl)ethane1,2-diamine, (DBDB) against the corrosion of carbon steel and H2 production in 1.0 M HCl solution was studied. The experimental methods of mass loss, gasometry, potentiodynamic polarization, PDP, and electrochemical impedance spectroscopy, EIS, were utilized. The PDP data confirmed that the DBDB compound attitude is a mixed-type inhibitor. The protection efficacy rises with increasing the added amount of DBDB to reach 97% at 0.005 M concentration and 25 °C. The mitigation process was based on the adsorption of the DBDB molecules on the carbon steel obeying Langmuir’s model. Some thermodynamic functions like Kads and ΔG°ads are computed and discussed. The negative sign of ΔG°ads proves the stability of the adsorbed DBDB molecules on the corroded metal surface. The ΔG°ads values vary between −38.70 and −35.13 kJ/mol explaining the existence of both the physical- and chemisorption mixed processes. The lowering in the Kads value with temperature confirms that the adsorption of DBDB compound is favorable at lower temperatures. Theoretical quantum calculations agreed with the experimental data.