Abdel-Karim Amal M, Azzam Rasha A, Shehata Omnia El-Said, Adly Mohamed A, El-Shamy Omnia A A, El Mahdy Gamal A
Physical Chemistry Department, National Research Centre, 33 El Bohouth St., Dokki, P.O.12622, Giza, Egypt.
Cemistry Department, Faculty of Science, Helwan University, Cairo, 11795, Egypt.
Sci Rep. 2025 Aug 2;15(1):28196. doi: 10.1038/s41598-025-12838-2.
Guanidine benzothiazole (G) and 1-(benzo[d]thiazol-2-yl)-3-methylguanidine (AG) were successfully synthesized and characterized by infrared (FT-IR) and nuclear magnetic resonance (NMR) spectroscopy. Both compounds act as novel corrosion inhibitors for carbon steel in 1.0 M hydrochloric acid solution. Their inhibition efficiency was evaluated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS). Surface analysis via scanning electron microscope (SEM) and energy dispersive X-ray (EDX) confirmed the formation of a protective film on the steel surface. PDP results indicate that G and AG function as mixed-type inhibitors, with inhibition efficiency increasing with concentrations, reaching a maximum of 80% for G and 91.4% AG. The AG compound was seen to retard the rate of corrosion of carbon steel more effective than PP compound. Adsorption followed the Langmuir isotherm, suggesting monolayer adsorption on the metal surface. The high inhibition efficiencies were attributed to strong adsorption and the formation of a dense, protective barrier film. The corrosion inhibition performance of the synthesized molecule was evaluated using density functional theory (DFT). Quantum chemical parameters, including highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO), energy gap, hardness, and dipole moment, and other quantum descriptors were analyzed. Density functional theory (DTF) calculation supported the experimental finding, showing that the high efficiency correlates with a low energy gap and high dipole moment, which promote electron transfer and adsorption strength. Theoretical and experimental results showed strong agreement, confirming the potential of G and AG as effective inhibitors for carbon steel.
成功合成了胍基苯并噻唑（G）和1-（苯并[d]噻唑-2-基）-3-甲基胍（AG），并通过红外光谱（FT-IR）和核磁共振（NMR）光谱对其进行了表征。这两种化合物在1.0 M盐酸溶液中均作为碳钢的新型缓蚀剂。使用动电位极化（PDP）和电化学阻抗谱（EIS）评估了它们的缓蚀效率。通过扫描电子显微镜（SEM）和能量色散X射线（EDX）进行的表面分析证实了在钢表面形成了保护膜。PDP结果表明，G和AG作为混合型缓蚀剂起作用，缓蚀效率随浓度增加而提高，G的最高缓蚀效率达到80%，AG为91.4%。发现AG化合物比PP化合物更有效地减缓碳钢的腐蚀速率。吸附遵循朗缪尔等温线，表明在金属表面上为单分子层吸附。高缓蚀效率归因于强吸附和形成致密的保护阻挡膜。使用密度泛函理论（DFT）评估了合成分子的缓蚀性能。分析了量子化学参数，包括最高占据分子轨道（HOMO）和最低占据分子轨道（LUMO）、能隙、硬度和偶极矩以及其他量子描述符。密度泛函理论（DTF）计算支持了实验结果，表明高效率与低能隙和高偶极矩相关，这促进了电子转移和吸附强度。理论和实验结果显示出很强的一致性，证实了G和AG作为碳钢有效缓蚀剂的潜力。
