亚临界条件下地沟油制备生物柴油副产物中有机氯化物的定性检测及来源分析

Qualitative detection and source analysis of the organic chlorides in the byproducts of biodiesel prepared using swill-cooked dirty oil under sub-critical conditions

该文介绍了一种生物柴油副产物粗甘油和拔出轻组分中有机氯化物的气相色谱-质谱(GC-MS)定性检测方法。样品来自于亚临界条件下地沟油与甲醇的酯交换反应,总氯含量较高。在GC-MS分析之前采用正己烷萃取脱除样品中的脂肪酸甲酯和游离脂肪酸等脂溶性干扰组分,对参考标准样品3-氯代甘油和2-氯代甘油以及样品的脱脂水相部分进行苯硼酸衍生化、正己烷萃取、浓缩等处理,经正己烷复溶后进行GC-MS分析。结果表明,生物柴油副产物中的有机氯化物主要为3-氯代甘油和2-氯代甘油。参考已有文献的研究结果和生物柴油制备工艺对有机氯化物的来源进行了讨论,推断原料地沟油中存在的大量无机氯盐是导致产生3-氯代甘油和2-氯代甘油的主要原因。

This paper introduces a gas chromatography-mass spectrometry (GC-MS) qualitative detection method for organic chlorides in crude glycerol and distillated light components, which are the byproducts of biodiesel. Samples with a higher total chlorine content were obtained from the transesterification reaction between swill-cooked dirty oil and methanol under subcritical conditions. Before GC-MS analysis, n -hexane extraction was performed to remove the soluble lipid interfering components, such as methyl fatty acid ester and free fatty acids, from the samples. Moreover, the reference standards, 3-chlorinated glycerol and 2-chlorinated glycerol, and the degreased water phases of the samples were subjected to derivatization with phenylboronic acid (PBA), extraction with n -hexane, and concentration. After re-dissolution using n -hexane , GC-MS analysis was performed. The results showed that the organic chlorides in the biodiesel by-products mainly included 3-chlorinated glycerol and 2-chlorinated glycerol. The sources of the organic chlorides were discussed by considering previously reported results and the preparation process of the biodiesel. Therefore, we concluded that the presence of a large amount of inorganic chloride salts in the swill-cooked dirty oil is the main reason for the production of 3-chlorinated glycerol and 2-chlorinated glycerol.