Sargassum Extract As A Biological Corrosion Inhibitor for Carbon Steel in Hydrochloric Acid

G. Serrano-Villanueva¹, L. P. Alvarez-Berber², E. C. Menchaca-Campo¹, and J. Uruchurtu- Chavarín¹

1. Universidad Autonoma del Estado de Morelos- CIICAp, Mexico

2. Universidad Autonoma del Estado de Morelos- CIQ, Mexico

Abstract: The metallic corrosion inhibition effect of the invasive brown seaweed Sargassum (natans and fluitans) extract, harvested from the Caribean sea in the coast of Mexico, against the corrosion of carbon steel in 0.5 M HCl medium was studied using electrochemical techniques namely: polarization resistance, impedance, and noise measurements. The hexane and di-chloride methane crude extracts of Sargassum is rich in alginate biopolymer. The corrosion evaluation tests showed that this algal extract acts as corrosion inhibitor for carbon steel substrate in 0.5 M HCl since inhibition efficiency of 93% was reached with 1 g/l of Sargassum extract at room temperature. AC impedance findings showed that the seaweed extract adding in the corrosive electrolyte increases the polarization resistance and conversely decreases the double layer capacitance at the interface. Adsorption of Sargassum on the substrate surface followed the Langmuir adsorption isotherm demonstrating that the corrosion inhibition mechanism of carbon steel substrate in 0.5 M HCl environment by the investigated algal extract is typical of the physisorption process and the protective barrier is mainly formed by the adsorbed biological macromolecules.

Key words: sargassum, corrosion protection, inhibitor, biopolymer