Abstract

In this work, the effect of Henna extract as an inhibitor on the corrosion behavior of API 5L Gr.B steel in H₂S-containing solution at 25 ˚C was investigated. The electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests were used for determination of corrosion parameters in the blank sample and samples with different concentrations of the extract. The obtained results indicated that with increasing Henna extract concentration, the corrosion current density decreased and the inhibition efficiency increased. The calculated efficiency of EIS and polarization tests showed good agreement. The studied inhibitor in this work follows the Langmuir adsorption isotherm and the type of surface adsorption is physical. Quantum chemical parameters such as energy gap (\(\Delta{\text{E}}\) = E_HOMO – E_LUMO), lowest unoccupied molecular orbital energy (E_LUMO), highest occupied molecular orbital energy (E_HOMO), hardness (\(\eta\)) and electronegativity (\({\chi}_{\text{inh}}\)) for the main constituents of Henna extract were calculated. The results of quantum chemistry proved that the main constituent of Henna extract and the inhibition agent was Lawsone.

Graphic abstract

中文翻译：

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指甲花提取物性能对API 5L钢在含H 2 S介质中的缓蚀性能的评估及其成分的DFT量子计算

摘要

在这项工作中，研究了指甲花提取物作为抑制剂对API 5L Gr.B钢在25°C的含H ₂ S溶液中的腐蚀行为的影响。电化学阻抗谱（EIS）和电势极化测试用于确定空白样品和具有不同浓度提取物的样品中的腐蚀参数。所得结果表明，随着指甲花提取液浓度的增加，腐蚀电流密度降低，缓蚀效率提高。EIS的计算效率和极化测试显示出良好的一致性。在这项工作中研究的抑制剂遵循Langmuir吸附等温线，并且表面吸附的类型是物理的。量子化学参数，例如能隙（\（\ Delta {\ text {E}} \） = E _HOMO – E _LUMO），最低未占用分子轨道能（E _LUMO），最高占用分子轨道能（E _HOMO），硬度（\（\ eta \））计算出指甲花提取物的主要成分的电负性（\（{\ chi} _ {\ text {inh}} \））。量子化学结果证明，指甲花提取物和抑制剂的主要成分是劳森。

图形摘要