PDF(Pubmed)
Abstract：
In the present work, Verbena Officinalis (VO) leaf extract was used as potential corrosion inhibitor for the corrosion of carbon steel (CS) in 0.5 M H2SO4 medium. Further, the corrosion inhibiting nature of VO leaf extract towards the CS was evaluated using mass loss (ML), potentiodynamic polarization (PDP), electrical impedance spectroscopy (EIS) and surface morphological analyses using atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS) techniques. Calculation of activation energy E a ∗ using Arrhenius equation shows the increase in activation energy when adding the VO leaf extract in 0.5 M H2SO4 medium and the maximum activation energy ( E a ∗ = 49.9 kJ mol-1) was observed for 1000 mg L-1 VO leaf extract in acid medium. The negative free energy values suggested the spontaneous and the stability of the adsorbed layer of VO leaf extract on the CS surface. Using EIS measurements, high percent inhibitory effectiveness of 91.1% for 1000 ppm solutions was achieved. With an increase in VO leaf extract dose, the double layer capacitance (Cdl) values fall while the values of charge transfer (Rct) increase. This showed that a protective layer of VO leaf extract on CS surface was formed. The polarization curves showed that the VO leaf extract acts as a mixed-type inhibitor. It is discovered that the adsorption of VO leaf extract molecules adhering to the CS surface followed the Langmuir isotherm. The anti-corrosion action of VO leaf extract is fully demonstrated by some surface techniques.
摘要：
在目前的工作中,马鞭草（VO）叶提取物被用作潜在的缓蚀剂，用于在0.5MH2SO4介质中腐蚀碳钢（CS）。Further,使用质量损失(ML)评估VO叶提取物对CS的腐蚀抑制性质，动电位极化(PDP),使用原子力显微镜（AFM）和X射线光电子能谱（XPS）技术进行电阻抗谱（EIS）和表面形态分析。使用阿伦尼乌斯方程计算活化能Ea*显示，在0.5MH2SO4培养基中添加VO叶提取物时，活化能增加，对于1000mgL-1VO叶提取物，观察到最大活化能（Ea*=49.9kJmol-1）在酸性培养基中。负自由能值表明CS表面上VO叶提取物吸附层的自发和稳定性。使用EIS测量，对于1000ppm溶液，实现了91.1%的高百分比抑制效果。随着VO叶提取物剂量的增加，双层电容(Cdl)值下降,而电荷转移(Rct)值增加。这表明在CS表面上形成了VO叶提取物的保护层。极化曲线表明，VO叶提取物作为混合型抑制剂。发现粘附在CS表面的VO叶提取物分子的吸附遵循Langmuir等温线。一些表面技术充分证明了VO叶提取物的防腐蚀作用。
