Adsorption and corrosion inhibition of some tripodal compounds for mild steel in molar hydrochloric acid medium

The inhibition effects of 2-{N,N-bis[(5-methyl-1-pyridin-2-yl-1H-pyrazol-3-yl)methyl] amino} ethanol (PPN) and 3- [ N,N-bis(thien-2-ylmethyl)amino]propan-1-ol (TTN) on the corrosion of mild steel in 1 M hydrochloric acid solution were investigated by weight loss and electrochemical polarization curves. The results revealed that both products were very good inhibitors at very low concentration and acted as mixed-type inhibitors. The adsorption of PPN and TTN on mild steel surface basically obeyed to the Langmuir adsorption isotherm model. The effect of temperature on the corrosion behaviour of mild steel was also studied in the temperature rang 25-80°C. The thermodynamic parameters such as adsorption heat (ΔadsH0) and adsorption free energy (ΔadsG0) were calculated and discussed.