New thio-compounds as corrosion inhibitor for steel in 1 M HCl

Some S-containing compounds newly synthesised have been tested as inhibitors for the corrosion of steel in I M HCl solution. Weight loss measurements, potentiodynamic polarisation and impedance spectroscopy (EIS) methods are used. The inhibiting action increases with the concentration of the compounds tested. The highest efficiency 95% is obtained at 10(-4) M of [(11-hydroxyundecyl)thio]acetic acid ((3) under bar and (4) under bar). We note good agreement between gravimetric and electrochemical methods (potentiodynamic polarisation and EIS). Polarisation measurements show also that (3) under bar and (4) under bar act as mixed inhibitors. The cathodic curves indicate that the reduction of roton at the steel surface happens with an activating mechanism. (3) under bar adsorbs on the steel surface according to Langmuir adsorption model. Effect of temperature is also studied between 308 K and 353 K. (c) 2005 Published by Elsevier Ltd.