High-value use of whole plants of Eupatorium Adenophora Spreng for aluminium in hydrochloric acid anti-corrosion

Abstract

The differences in corrosion inhibition properties and adsorption mechanisms of Eupatorium Adenophorum Spreng leaves (EASLE), stems (EASSE) and root extracts (EASRE) prepared by thermal reflux method on aluminum in 1.0 M HCl solution were investigated. Findings illustrated that all three extracts demonstrated excellent corrosion inhibition, and 1.0 g/L EASLE had the most excellent performance (η_w as high as 98.43 %). The electrochemical reaction adhered to the ‘geometric coverage effect’, where the addition of the inhibitors increases the charge transfer resistance by eightfold, thereby suppressing the corrosion reaction. The presence of elements and functional groups (O–H, CO, CC, etc.) related to the extracts on the aluminum surface was detected by FTIR and XPS, confirming the adsorption of the extracts. All three extracts contained terpenoids, alkaloids, and other active substances, but the relative content varied significantly. LC-MS analysis revealed that the superior corrosion inhibition performance of EASLE is attributed to the higher relative content of active components, Coumarin and Erucamide. Experiments on single chemical components containing O heteroatoms showed lower corrosion inhibition efficiency (20 %–65 %) compared to the extracts. Theoretical calculations pointed out from the molecular level that the active sites of the compounds are predominantly concentrated in O–H, CO, further suggesting that the significant corrosion inhibition performance of the extracts results from the synergistic effects of multiple components. This study broadens the high-value utilization of Eupatorium Adenophorum Spreng and provides a theoretical basis for its extracts as a greener and more efficient inhibitor of aluminum in acidic media.