Ethanolamine morpholine oleate as corrosion inhibitor for mild steel in acid solutions

Abstract

Ethanolamine morpholine oleate was prepared by direct esterfication and ring closure of triethanolamine monooleate. The structure was characterised by elemental microanalysis and Fourier transform infrared spectroscopy. The product was evaluated as a corrosion inhibitor for mild steel in 10 vol.-%HCl and 10 vol.-%H₂SO₄ solutions. The behaviour of the product was studied in various concentrations (50-250 ppm) at different temperatures (25, 45, and 60°C) using a potentiodynamic technique. The inhibitor proved its effectiveness in both HCl and H₂SO₄ solutions, with its efficiency in HCl exceeding that in H₂SO₄ solution. NaCl in the solution exhibited a synergistic effect on the inhibition of mild steel in H₂SO₄ solution. The inhibition efficiency increased with increasing concentration and decreased with increasing temperature.