氧化前后生物柴油的红外和紫外光谱分析

FT-IR and UV Spectral Analysis of Biodiesel Before and After Oxidation

利用红外光谱和紫外光谱分析了菜籽油生物柴油、大豆油生物柴油及餐饮废油生物柴油中不饱和脂肪酸甲酯(FAME)在氧化过程中分子构型的变化。结果表明,生物柴油的氧化安定性与其脂肪酸甲酯的组成密切相关,即不同来源的生物柴油的氧化安定性不同。在氧化过程中,不饱和脂肪酸甲酯分子中的双键会发生顺-反异构化,并生成共轭双键;多双键不饱和脂肪酸甲酯含量越高,共轭双键生成量越多,生物柴油的氧化安定性也越差。

The structural transformation of unsaturated fatty acid methyl ester （FAME） of rapeseed oil derived biodiesel（RME）, soybean oil derived biodiesel（SME） and waste oil based biodiesel （WME）, was analyzed by FT-IR and UV. The results demonstrated that the oxidation behaviors of biodiesels were closely related to their compositions of FAMEs, meaning that biodiesels from different origins exhibited different oxidation resistance. During oxidation process of biodiesel, cis-trans isomerization occurred in the unsaturated FAME molecules and conjugated double-bond was produced. The higher the mass fraction of unsaturated FAME with multi-double bonds in biodiesel and the more the conjugated double bonds, the poorer the oxidation resistance of biodiesel.