New Schiff base cationic surfactants as corrosion inhibitors for carbon steel in acidic medium: weight loss, electrochemical and SEM characterization techniques

Abstract

Two new Schiff base cationic surfactants were synthesized and their chemical structures confirmed using FTIR spectroscopy. The tensioactive and thermodynamic characteristics of their solutions were determined using surface tension/log concentration plots. The protection performance of the synthesized compounds against carbon steel corrosion in 1 M HCl solution was evaluated using weight loss and electrochemical techniques. The compounds were found to be excellent corrosion inhibitors, and their efficiency increased with increasing inhibitor concentration. The mode of adsorption obeyed the Langmuir adsorption isotherm. Polarization curves showed that the two compounds were mixed–type inhibitors. The temperature dependence of the corrosion rate in the absence and presence of these compounds was studied in a temperature range of 303 to 333 K using the weight loss data. Activation parameters E a, ΔH a o , and ΔS a o were determined and discussed. In addition, the presence of a protective film on the carbon steel surface was confirmed using scanning electron microscopy (SEM).