El Hawary Maha, Campos Othon S, Kerroum Younes, Bellaouchou Abdelkbir, Amin Hatem M A, Boudalia Maria
Laboratory of Materials, Nanotechnology and Environment, Faculty of Sciences, Mohammed V University in Rabat P.O. Box 1014 10000 Rabat Morocco.
Department of Chemistry and Physics, Federal University of Espírito Santo 29500-000 Alegre-ES Brazil.
RSC Adv. 2025 Sep 12;15(40):33297-33311. doi: 10.1039/d5ra04888e. eCollection 2025 Sep 11.
This work demonstrates the recycling potential of a hydroalcoholic extract of spent coffee waste (HECG) as an environmentally friendly additive to soybean cooking oil (SWCO) biodiesel, alleviating its corrosive impacts on a Cr-rich stainless-steel alloy. The extract is efficiently produced using the Soxhlet extraction method, and its chemical profile is analyzed using GC-MS and FTIR. Furthermore, the anticorrosive properties of HECG are thoroughly evaluated using gravimetry, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The HECG additive shows excellent inhibitory efficacy (94%) on 307 L stainless steel. The polarization results underline the mixed inhibitory character of HECG. The metal surface is primarily protected against biodiesel-induced corrosion through adsorption of additive molecules onto it. Additionally, SEM-EDX and XRD techniques are used to evaluate the microstructure, crystal structure, and composition of the surface and formed products after immersion in this biodiesel. The results showcase the additional protection of the 307 L sample via creating a passive oxide film (CrO, FeO, FeOOH) on the metal surface, thus boosting its corrosion resistance. Importantly, DFT and Fukui function simulations identify the electrophilic and nucleophilic sites at the β-turmerone molecule, the major component of the extract, and reveal intrinsic retro donations in both ways - additive to metal and/or metal to additive.
这项工作展示了咖啡渣水醇提取物（HECG）作为大豆烹饪油（SWCO）生物柴油的环保添加剂的回收潜力，减轻了其对富铬不锈钢合金的腐蚀影响。该提取物采用索氏提取法高效制备，并使用气相色谱-质谱联用仪（GC-MS）和傅里叶变换红外光谱仪（FTIR）分析其化学特征。此外，通过重量法、动电位极化和电化学阻抗谱（EIS）全面评估了HECG的防腐性能。HECG添加剂对307L不锈钢显示出优异的抑制效果（94%）。极化结果突出了HECG的混合抑制特性。金属表面主要通过添加剂分子吸附在其上而免受生物柴油引起的腐蚀。此外，使用扫描电子显微镜-能谱仪（SEM-EDX）和X射线衍射仪（XRD）技术评估了浸泡在这种生物柴油中后表面和形成产物的微观结构、晶体结构和组成。结果表明，通过在金属表面形成钝化氧化膜（CrO、FeO、FeOOH），307L样品得到了额外的保护，从而提高了其耐腐蚀性。重要的是，密度泛函理论（DFT）和福井函数模拟确定了提取物主要成分β-姜黄酮分子上的亲电和亲核位点，并揭示了两种方式的内在逆向给予——添加剂到金属和/或金属到添加剂。
