Efficiency Evaluation of Anti-corrosion Treatment of Carbon Steel by Extracts of Red Algae Collected from Mediterranean Coast

The paper presents the assessment of inhibition effectiveness of biomolecules extracted from red seaweed against biocorrosion in the petroleum industry. The first objective of this study was to obtain extracts (A, B and C, prepared respectively from red algae species: Corallina ellongata, Gymnogongrus crenulatus and Pterocladia capillacea) by ethanol extraction method. The infrared spectra of the three extracts confirmed the presence of amine derivatives molecules known by their anti-corrosion inhibiting powers. The second objective was based on the identification of physico-chemical characteristics of the extracts and thus revealing their inhibitory and / or bactericidal power in bacterial corrosion of carbon steel in injection water contaminated with sulfato-reducing bacteria. Biological test of all extracts gave a concentration upto 10 germs/mL in contaminated water by sulfato-reducing bacteria during 28 days of incubation at 37�C. Evolution in time of the open-circuit potential showed a longer incubation time for electrolyte with extracts, whereas the stabilization time was shorter. Current corrosion density, polarization resistance, charge transfer resistance and double layer capacity were determined by using linear polarizarion resistance technique and electrochemical impedance spectroscopy. The corrosion protection efficiency of extract obtained from Gymnogongrus crenulatus (extract B) reached a maximum protective capacity of 99.69% at 5 ppm in the injection water.