Experimental and Theoretical Study on Corrosion Inhibition of Mild steel in 20 % Formic Acid Solution Using Schiff Base-Based Cationic Gemini Surfactant

Abstract

AbstractThe paper investigates the adsorption and corrosion inhibition behavior of Schiff base-based cationic gemini surfactant bis-[p-(N,N,N-dodecyldimethylammonium bromide) benzylidene]thiourea, designated as (12-S-12) on mild steel in 20 % formic acid solution in the temperature range of 30 – 60 °C. The synthesized inhibitor was characterized using nuclear magnetic resonance spectroscopy (NMR). The adsorption and corrosion inhibition mechanism of the inhibitor was elaborated using weight loss measurements, solvent analysis of iron ions, potentiodynamic polarization measurements, electrochemical impedance measurements, measurement of thermodynamic/kinetic parameters and quantum chemical calculations. The surface morphology of the corroded mild steel specimen was evaluated using scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDAX). The inhibition efficiency of the compound was found to vary with the inhibitor concentration and temperature. The inhibitor was found to be a mixed type inhibitor. Adsorption process on mild steel surface followed Langmuir's model adsorption isotherm.