Vergara-Juarez Fabiola, Porcayo-Calderon Jesus, Perez-Orozco Juan Pablo, Acevedo-Quiroz Macdiel Emilio, Bustos-Terrones Victoria, Quinto-Hernandez Alfredo
Tecnológico Nacional de México/Instituto Tecnológico de Zacatepec, Departamento de Ingeniería Química y Bioquímica, Calzada Tecnológico 27, Zacatepec de Hidalgo 62780, Morelos, Mexico.
Departamento de Ingeniería Química y Metalurgia, Universidad de Sonora, Hermosillo 83000, Sonora, Mexico.
Materials (Basel). 2024 Apr 16;17(8):1821. doi: 10.3390/ma17081821.
Biodiesel is a mixture of saturated and unsaturated Fatty Acid Methyl Esters (FAMEs) whose composition affects the corrosion behavior of metal containers during storage. This study examines the effect of the C=C bond present in selected FAMEs (Methyl Stearate, Methyl Oleate, and Methyl Linoleate) in aluminum corrosion in the absence of oxygen. First, mass loss assays were carried out at 100, 200, and 280 °C for 1000 h using pure Methyl Stearate (MS), 5% Methyl Oleate in Methyl Stearate (MS-5% MO), and 5% Methyl Linoleate in Methyl Stearate (MS-5% ML). Next, chemical changes in FAMEs were studied using FTIR, TGA, and GC/MS. SEM/EDS analysis allowed us to inspect the aluminum surfaces and their chemical characterization. We estimated higher corrosion rates for MS assays than those of unsaturated methyl ester mixtures. In a separate set of experiments, we used electrochemical techniques (potentiodynamic polarization, linear polarization resistance, and electrochemical impedance spectroscopy) to investigate aluminum corrosion induced by thermal-degraded products from FAMEs at 100, 200, and 280 °C for 300 h able to dissolve in aqueous extracts. These electrochemical experiments revealed that the products in the aqueous extracts from the unsaturated methyl ester mixture form a passive layer on the Al surface thicker than pure MS at the corresponding degradation temperatures.
生物柴油是饱和脂肪酸甲酯（FAMEs）和不饱和脂肪酸甲酯的混合物，其成分会影响储存期间金属容器的腐蚀行为。本研究考察了所选FAMEs（硬脂酸甲酯、油酸甲酯和亚油酸甲酯）中存在的C=C键在无氧条件下对铝腐蚀的影响。首先，使用纯硬脂酸甲酯（MS）、硬脂酸甲酯中5%的油酸甲酯（MS-5%MO）和硬脂酸甲酯中5%的亚油酸甲酯（MS-5%ML）在100、200和280°C下进行1000小时的质量损失测定。接下来，使用傅里叶变换红外光谱（FTIR）、热重分析（TGA）和气相色谱/质谱联用（GC/MS）研究FAMEs的化学变化。扫描电子显微镜/能谱分析（SEM/EDS）使我们能够检查铝表面及其化学特征。我们估计MS测定的腐蚀速率高于不饱和甲酯混合物的腐蚀速率。在另一组实验中，我们使用电化学技术（动电位极化、线性极化电阻和电化学阻抗谱）研究了在100、200和280°C下300小时FAMEs热降解产物诱导的铝腐蚀，这些产物能够溶解在水提取物中。这些电化学实验表明，在相应的降解温度下，不饱和甲酯混合物水提取物中的产物在铝表面形成的钝化层比纯MS形成的钝化层更厚。
