Comparison of organic extracts from sargassum as corrosion inhibitors of API 5L X52 steel obtained with different solvents

Abstract

In this work, comparative results are presented of the evaluation of organic seaweed extracts as corrosion inhibitors of API 5L X52 steel, coming from 2 different sites on the Yucatán Peninsula. The extraction was carried out in a polar inorganic medium (water), a polar organic medium (methanol), and an intermediate polarity organic medium (acetone), whose products were added at 10, 25, and 50 ppm in a 0.5 M sulfuric acid solution as electrolyte. Electrochemical tests of polarization resistance, Tafel extrapolation, and electrochemical impedance spectroscopy show that in some cases, the extracts increase the steel's charge transfer resistance, thereby reducing the corrosion rate and thus exhibiting an inhibitory effect. With acetone extracts as a solvent, the rates were reduced from 0.00193 to 0.000058 (A/cm²), achieving an inhibition efficiency of over 90%, which indicates that the extracts in this medium adsorb with greater energy to the metal surface. No direct relationship was observed between the sargassum sample site, nor the extraction medium, in the contribution to corrosion inhibition.