Thiophene derivatives as effective inhibitors for the corrosion of steel in 0.5 M H2SO4

The inhibition of the corrosion of the steel in 0.5 M H2SO4 by thiophene compounds is studied by weight loss and electrochemical polarisation. The results obtained reveal that these compounds are very efficient inhibitors. The inhibition efficiency increases with the increase of inhibitor concentration to reach 98% at 5 x 10(-3) M for the 2-ethylamine thiophene. Potentiodynamic polarisation studies clearly reveal that the presence of thiophenes does not change the mechanism of the hydrogen evolution reaction and they act essentially as cathodic inhibitors. The temperature effect on the corrosion behaviour of steel is studied in the range from 298 to 353 K without and with thiophene at 10(-3) M. The inhibitors 2-ethylamine thiophene and 3-ethylamine thiophene adsorb on steel according to Frumkin isotherm model. (C) 2003 Elsevier B.V. All rights reserved.