Synergistic Effect Of Chloride And Bromide Ions On Corrosion Inhibition Of Steel In 1 Mol L^-1 Phosphoric Acid Using Cationic Gemini Surfactant

Zhen-Yu Wu^1,2, Zheng Fang¹, Wang Zhang²,
Ling-Guang Qiu^2*, An-Jian Xie², Yu-Hua Shen^2
1School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, (CHINA)
²Laboratory of Advanced Porous Materials, School of Chemistry and Chemical Engineering, Anhui University, Hefei 230039, (CHINA)

Synergism between a cationic gemini surfactant, 1,2-ethane-bis(dimethyl dodecyl ammonium bromide) (12-2-12), and halide ion (Br^- or Cl^-) for corrosion inhibition of cold rolled steel in 1.0 mol L^-1 phosphoric acid was investigated by using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods. Some thermodynamic parameters were calculated by fitting experimental data with Langmuir model. Potentiodynamic polarization studies reveal that the inhibition species is a mixed-type inhibitor. EIS measurements suggest that the presence of inhibitor molecules in acidic solution decreases double layer capacitance and increases the charge transfer resistance, indicating the formation of a protective layer on steel surface.