Sargassum seaweed extract as a novel green corrosion inhibitor for API-5L carbon steel

Abstract

Sargassum extract was studied as a novel green corrosion inhibitor against the corrosion of API-5L carbon steel in 0.1 M HCl solution. The inhibiting action of this extract was investigated using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). In addition, FTIR was employed to identify the main compound of Sargassum extract. The Sargassum extract was prepared by the maceration process. The maceration process takes 72 h to produce the filtrate. To obtain the Sargassum extract, the filtrate that resulted from the maceration process was evaporated. The inhibitor concentration was varied from 50 ppm, 100 ppm, 200 ppm, 400 ppm, to 500 ppm. Furthermore, the temperature and exposure time were also varied to determine their effect on the inhibitor efficiency. The temperature was varied as follows: room temperature, 40°C, and 50°C. The specimens were measured with two conditions, i.e., with and without pre-exposure for 30 min. The inhibitor efficiency increased when inhibitor concentration, temperature, and exposure time increased according to the polarization test results. Interestingly, Sargassum extract (500 ppm) manifested inhibition efficiency up to 95% with 30 min exposure time. Moreover, the presence of aromatic rings (C=C), hydroxide (O–H), and organic compounds (C–H) was confirmed by FTIR. The results indicate that Sargassum seaweed extract is a good green corrosion inhibitor.