Electrochemical investigation and Quantum chemicalstudies on corrosion inhibition for ester-quats surfactants on iron in hydrochloricacid

The corrosion inhibition of iron in 1m hydrochloric acid solution in the presence of two ester quat surfactants; the mono ester quat: dodecanoyloxypropyl dodecyl dimethyl ammonium bromide (meq) and the gemini ester quat: 1,3bis-(dodecanoyloxypropyl dimethyl ammonium) propane dibromide (geq) was investigated using potentiodynamic polarization,electrochemical impedance spectroscopy (eis) and surface analysis (sem) techniques. tafel curves showed that the corrosion current density decreases with addition of various concentrations of both inhibitors. however,it was noted that geq is more efficient than meq. indeed,the inhibition efficiency of geq at 2.10-4m reaches 96% against 87% for meq in acidic media. these surfactants act as good mixed inhibitors. eis measurements showed that the studied compounds inhibit iron corrosion by adsorption of surfactant molecules on the iron surface. the effect of molecular structure on the inhibition efficiency was studied by theoretical methods (hf,dft). experimental and theoretical studies agree well and confirmed that geq is the best corrosion inhibitor. © 2017,university of mohammed premier oujda morocco.