Three Gemini cationic surfactants based on polyethylene glycol as effective corrosion inhibitor for mild steel in acidic environment

Three Gemini quaternary ammonium surfactants based on polyethylene glycol have been prepared and characterized using FTIR and ¹HNMR spectra. The effect of ethylene oxide units’ number on the steel corrosion in 1.0 M HCl has been estimated using weight loss, polarization and electrochemical impedance spectroscopy. The Gravimetric technique has been done at three different temperatures 25, 40 and 55 °C. The synthesized Gemini cationic surfactants with the higher molecular weight (higher number of ethylene oxide units) showed the higher inhibition efficiency under all conditions. All the prepared Gemini inhibitors showed higher inhibition efficiency upon raising the solution temperature from 25 to 55 °C. The synthesized inhibitor G1500Br showed inhibition efficiency reach to 94% at temperature 55 °C. The Langmuir adsorption isotherm is the best-fitted isotherm concerning the tested Gemini surfactants adsorption onto steel surface. The change in the free energy of adsorption refers to physicochemical adsorption on steel surface. The synthesized materials act as a mixed-type inhibitor based on the potentiodynamic polarization results.