Abstract
The inhibiting effect of cationic surfactant N, N, Ndimethyl 4methylbenzyl dodecyl ammonium chloride on mild steel in hydrochloric acid solutions was investigated by surface and thermodynamic measurements, weight loss tests, polarization measurements and EDS techniques. The data obtained from surface and thermodynamic measurements with the inhibitor indicate that the area per molecule slightly increases with increasing temperature and both absorption and micellization processes are spontaneous. Weight loss measurement showed that the inhibition efficiencies increased with increasing surfactant concentration and attained a maximum around their critical micelle concentration. Polarization studies reveal that the inhibitor behaves as a mixed type in hydrochloric acid solutions and acted on the cathodic reaction without modifying the mechanism of the hydrogen evolution reaction. EDS measurement showed high coverage of surfactant on the mild steel surface.