Preparation and Mixture Corrosion Inhibition of Doped Polianiline for Mild Steel

Polyaniline acid (PAAC) was chosen as doping acid to prepare polyaniline( PANI) by direct chemical oxidation. The results of FTIR absorption spectra were used to characterize the product. And the inhibition effects of single and compound PANI on corrosion of Q235 steel in 0.5 mol·L-1 HCl solution were investigated by polarization curvers and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion inhibition performance of PANI alone was just average. When the concentration of PANI was 20 mg·L-1, the best inhibition efficiency was only 73.6%. Corrosion inhibition performance was better when polyaniline was compounded with polyacrylamide, triethanolamine and urea, with a mass ratio of 1∶2∶1∶1 . When the concentration of polypaniline was 80 mg·L-1, the inhibition efficiency reached 92.7%. Adsorption of polyaniline on Q235 steel obbeys the modified Langmuir adsorption isotherm.