Waste cooking oils (WCO) can be used as feedstock for biodiesel (fatty acid ethyl or methyl esters—FAEE or FAME) production. Their usual high acidity, high moisture, and low stability can impair the reaction yield and generate a low‐quality biodiesel. Here, we performed liquid–liquid washings using WCO and ethanol‐based solvents with the goal of generating oil‐rich miscella as FAEE feedstocks with a higher quality than WCO. Three different solvents were evaluated: 99% ethanol, 95% ethanol, and the soybean oil extraction ethanolic phase (SEP), a by‐product with immense unexplored antioxidant potential obtained by extracting soybean oil using ethanol. Washings were performed in a 1000 mL flat‐bottom flask at 78.1 °C, using a 1:2 (w/v) oil/solvent ratio, under magnetic stirring (1200 rpm) for 10 min. Ethyl esters were prepared via homogeneous alkali transesterification using WCO and oil‐rich miscella as feedstocks. Treatments reduced the acid value by 40–61% and the peroxide value by 15–50%. Improvements in feedstock quality generated 24–54% higher biodiesel yields. The oil‐rich phase produced with SEP was 15% more resistant to oxidation than WCO. This was attributed to the transference of isoflavones from the SEP. However, biodiesel from treated samples presented equal or lower oxidative stability than FAEE from WCO. High‐performance liquid chromatography (HPLC) analysis showed that no isoflavones remained in biodiesel after purification. Pretreatment of WCO with ethanol‐based extracts such as the SEP has great potential to improve WCO quality for biodiesel production as it can be a source of plant‐based antioxidants.

中文翻译：

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大豆油提取的乙醛副产物改善生物柴油生产中的废食用油质量

废食用油（WCO）可用作生物柴油（脂肪酸乙酯或甲酯-FAEE或FAME）的生产原料。它们通常的高酸度，高水分和低稳定性会损害反应产率并产生劣质生物柴油。在这里，我们使用WCO和基于乙醇的溶剂进行了液-液洗涤，目的是生成富含油的杂油作为FAEE原料，其质量要比WCO高。评估了三种不同的溶剂：99％乙醇，95％乙醇和大豆油提取乙醇相（SEP），这是一种副产物，具有巨大的未开发的抗氧化潜能，该副产物是使用乙醇提取大豆油而获得的。在78.1°C的1000 mL平底烧瓶中，以1：2（w / v）的油/溶剂比率在磁力搅拌（1200 rpm）下洗涤10分钟。通过使用WCO和富含油的杂油作为原料，通过均相碱基酯交换反应制备乙酯。处理使酸值降低了40–61％，过氧化物值降低了15–50％。原料质量的提高使生物柴油的产量提高了24–54％。SEP产生的富油相的抗氧化性比WCO高15％。这归因于异黄酮从SEP的转移。但是，与WCO的FAEE相比，处理过的样品中的生物柴油具有相同或更低的氧化稳定性。高效液相色谱（HPLC）分析表明，纯化后生物柴油中没有残留异黄酮。用基于乙醇的提取物（例如SEP）对WCO进行预处理具有很大的潜力，可以提高生物柴油生产中的WCO质量，因为它可以作为植物类抗氧化剂的来源。