Vegetable polyol phosphate as corrosion inhibitor of carbon steel in packer fluid solutions

Glyoxal is a potential sequestrant of H2S in the pre-salt exploration. However, the mixture containing packer fluid and glyoxal is corrosive. The present work aims at enabling the use of glyoxal by addition of an environmentally friendly polyol phosphate as corrosion inhibitor. EIS, corrosion potential (Ecorr), and Tafel analysis over the immersion period of the AISI 1020 carbon steel were used in the investigation. Dosage (500 ppm) of polyol phosphate in glyoxal and packer fluid system increases the polarization resistance and decreases both the capacitance and the corrosion current. Polyol phosphate is effective as corrosion inhibitor, due to its adsorption on the metal surface or on the film of the previously formed oxide in good agreement with the Langmuir isotherm.