Some New Nonionic Surfactants Based on Propane Tricarboxylic Acid as Corrosion Inhibitors for Low Carbon Steel in Hydrochloric Acid Solutions

The effect of some new nonionic surfactants namely, N1,N2,N3-tris ((14-amino-3,6,9,12-tetraazatetradecyl) carbamothioyl) propane-1,2,3-tricarboxamide (compound I) and N1,N2,N3-tris((2-hydroxyethyl) carbamothioyl) propane-1,2,3-tricarboxamide (compound II) for the corrosion of low carbon steel (LCS) in 1.0 M HCl was evaluated by electrochemical and non-electrochemical techniques. From weight loss measurements, the concentration of these compounds and the temperature of the medium have a large effect on the inhibition efficiency (IE%). The IE% reached 93% for compound (I) and 77.7% for compound (II) at 75 ppm. The behavior of these compounds obeys the Temkin isotherm with good fitting. Polarization curves of these surfactants indicate that they affect both anodic metal dissolution and cathodic H2 evolution (i.e. mixed type). The action of the addition of these compounds on the LCS was detected using scanning electron microscopy, energy disperse X-ray, Fourier-transform infra-red (FTIR) spectroscopy and atomic force microscopy (AFM) techniques. Electrochemical and non-electrochemical methods gave matched results.