The extract of invasive alien weed Erigeron canadensis L.(ECE)was prepared by ultra-sound-assisted extraction.The corrosion inhibition performance of ECE as a corrosion inhibitor on steel in 1.0 mol/L HCI solution had been investigated by means of mass loss measurement,electrochemical method and metal surface characterization.The results show that ECE has good corrosion inhibition per-formance on steel in 1.0 mol/L HCI solution,and the corrosion inhibition rate increases with the increase of ECE concentration.Among others the corrosion inhibition rate of 300 mg·L-1 ECE at 40℃ is the best,reaching 93.7％.The adsorption of ECE on steel surface is consistent with Langmuir adsorption isotherm.The standard adsorption Gibbs free energy ranges from-28.37 kJ/mol to-27.60 kJ/mol at 20-50℃,and adsorption is a mixed type of physical and chemical adsorption.The potentiodynamic polarization curves show that ECE is a mixed inhibitor corrosion inhibitor acting through"geometrical overlay effect".The Ny-quist plot shows a single capacitive resistance arc,and the charge transfer resistance at the steel/acid in-terface increases with increasing ECE concentration,while the capacitance of the double layer decreas-es.Examination results of metallographic microscopy,atomic force microscopy(AFM),contact angle,FT-IR and UV-Vis show that the adsorption of ECE induced the formation a corrosion inhibition film on the steel surface significantly slows down steel corrosion in HCI solution and enhances the hydrophobicity of the steel surface.
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