Investigations of synergistic effect of surfactants as corrosion inhibitor on steel

The inhibition performances of the inhibitors C(8)TAB-MP (a mixture of octyltrimethylammonium bromide (C(8)TAB) and 4-mercaptopyridine (4MP)), C(8)TAB and 4MP toward A(3) steel in 0.5 M hydrochloric acid solution were studied at 25 degrees C. The studied inhibitors worked in a hybrid form, mainly controlling the cathodic reaction. Their adsorption follows the Langmuir isotherm, and the compositional combination is superior to the sum of their individual properties. The highest inhibition efficiency of C(8)TAB-MP was 99.4% at a concentration of 200 mg/l. The surface morphologies of samples were obtained from atomic force microscopy tests. The synergistic effect between C(8)TAB and 4MP was due to the C(8)TAB molecules donating electrons and the 4MP molecules accepting electrons.