Abstract

In the present study, the extract of Inula viscosa leaves (IVE) was used as an environmentally-friendly and green corrosion inhibitor for X70 carbon steel in 1 M HCl. The experimental results were endorsed by computational approaches. The corrosion inhibition effect of the extract was investigated by weight loss measurements, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Besides the surface characterization by SEM/EDS (scanning electron microscopy/energy dispersive X-ray spectroscopy) and AFM (atomic force microscopy), the mechanism of inhibition was assessed through FTIR and UV/Vis studies. The results of weight loss measurements and electrochemical experiments showed that IVE was an excellent corrosion inhibitor, as the corrosion inhibition efficiency was found to increase with the concentration of plant extract and exceeded 92% at a concentration of 600 mg L⁻¹. This excellent inhibitory efficiency was attributed to the efficient adsorption of this green inhibitor onto the steel surface and its mixed-type behavior; the adsorption data were fitted to the Langmuir isothermal model. The studies at an optimum concentration and for an immersion time of 120 h revealed the stability of adsorbed inhibitor layer on the X70 surface in acidic media. The success of the adsorption was confirmed by analysis of the organic protective film formed by SEM/EDS and FTIR tools. AFM showed a significant reduction of surface roughness of the susbtrate in the presence of IVE. Moreover, the adsorption-inhibition relationship was discussed in light of the quantum chemical parameters calculated for the main components of the plant extract using the density functional theory (DFT).

摘要

在本研究中，旋覆花提取物叶 (IVE) 在 1 M HCl 中用作 X70 碳钢的环保绿色缓蚀剂。实验结果得到了计算方法的认可。通过失重测量、动电位极化和电化学阻抗谱 (EIS) 技术研究了提取物的缓蚀效果。除了通过 SEM/EDS（扫描电子显微镜/能量色散 X 射线光谱）和 AFM（原子力显微镜）进行表面表征外，还通过 FTIR 和 UV/Vis 研究评估了抑制机制。失重测量和电化学实验结果表明 IVE 是一种优良的缓蚀剂，^-1。这种优异的抑制效率归因于这种绿色抑制剂在钢表面上的有效吸附及其混合型行为；吸附数据符合 Langmuir 等温模型。在最佳浓度和 120 小时浸泡时间下的研究揭示了 X70 表面吸附的抑制剂层在酸性介质中的稳定性。通过 SEM/EDS 和 FTIR 工具对形成的有机保护膜进行分析，证实了吸附的成功。AFM 显示，在 IVE 存在下，基材的表面粗糙度显着降低。此外，根据使用密度泛函理论（DFT）计算的植物提取物主要成分的量子化学参数，讨论了吸附-抑制关系。