Karki Nabin, Neupane Shova, Gupta Dipak Kumar, Yadav Amar Prasad
Central Department of Chemistry, Tribhuvan University Kathmandu Nepal
Bhaktapur Multiple Campus, Tribhuvan University Bhaktapur Nepal.
RSC Adv. 2023 Mar 8;13(11):7603-7613. doi: 10.1039/d3ra00148b. eCollection 2023 Mar 1.
Electrochemical methods were used to characterize the inhibition efficacy of the extract of the high-altitude plant as an environmentally acceptable inhibitor for mild steel in 1.0 M HSO. The was extracted in hexane and methanol separately and applied on mild steel (MS) as an inhibitor. A detailed electrochemical characterization such as potentiodynamic polarization, open circuit potential, and electrochemical impedance spectroscopy (EIS) was performed on the MS surface covered with the extract molecules. The hexane extracts adsorbed slower to the MS surface than the methanol extract, but both molecular extracts showed similar corrosion inhibition efficacies (IE). The IE for 1000 ppm extract in hexane and methanol was 73.10% and 91.99%, respectively, after 0.5 hour immersion of MS, whereas it was 98.79% and 96.73% in hexane and methanol extract after 24 hours of immersion of MS in acidic medium. The IE of the methanol extract increased with concentration. From the EIS analytical analysis, adsorption of inhibitor molecules on the charge transfer kinetics was confirmed. The potentiodynamic polarization showed a decrease in current density with the concentration of methanol extract without affecting the Tafel slopes. ATR-FTIR of the extract indicated the presence of the different functionalities in it. Adsorption of the extract molecules on the metal surface obeyed the Langmuir adsorption isotherm. The computed value of Δ* implies that the adsorption is of mixed type. The formation of a protective film of inhibitor molecules on the MS surface was confirmed from EIS and using a scanning electron microscope. The adsorption mechanism based on the experimental data supported by the thermodynamic calculations is highlighted in this article.
采用电化学方法表征了一种高海拔植物提取物作为1.0 M硫酸中低碳钢的环境友好型缓蚀剂的缓蚀效果。该提取物分别用己烷和甲醇萃取，并作为缓蚀剂应用于低碳钢（MS）表面。对覆盖有提取物分子的MS表面进行了详细的电化学表征，如动电位极化、开路电位和电化学阻抗谱（EIS）。己烷提取物在MS表面的吸附速度比甲醇提取物慢，但两种分子提取物的缓蚀效果相似。MS浸泡0.5小时后，己烷和甲醇中1000 ppm提取物的缓蚀效率分别为73.10%和91.99%，而在酸性介质中浸泡24小时后，己烷和甲醇提取物中的缓蚀效率分别为98.79%和96.73%。甲醇提取物的缓蚀效率随浓度增加而提高。通过EIS分析，证实了缓蚀剂分子在电荷转移动力学上的吸附。动电位极化表明，随着甲醇提取物浓度的增加，电流密度降低，而不影响塔菲尔斜率。提取物的ATR-FTIR表明其中存在不同的官能团。提取物分子在金属表面的吸附符合朗缪尔吸附等温线。计算得到的Δ*值表明吸附为混合型。通过EIS和扫描电子显微镜证实了在MS表面形成了缓蚀剂分子保护膜。本文重点介绍了基于热力学计算支持的实验数据的吸附机理。
