This research aims to ameliorate the oxidation and storage stability of Prosopis juliflora Methyl Ester (PJME) using the Rancimat method (EN14112). Agricultural waste-derived essential oils (AWEOs), such as Citrus Aurantifolia L. (CA), Curcuma longa L. (CL), and Eucalyptus camaldulensis Dehn (EC), were used as natural antioxidants alongside the commonly used synthetic antioxidant TBHQ. The concentrations of antioxidants ranged from 0% to 4% (v/v % of biodiesel). Results indicated that adding 4% CA to raw PJME extended the induction period (IP) from 2.64 h to 11.2 h at the end of 60 days, meeting EN14214 standards and exhibiting the highest antioxidant activity. TBHQ is less effective at lower concentrations; however, it is comparable to CL at higher concentrations. At 4% TBHQ with PJME, the IP was 9.9, 8.8, and 8.1 hours at the end of 15, 30, and 45 days of storage, respectively. Furthermore, this study uniquely compared the performance and emissions of a CI engine fuelled with a fresh B30 blend, B30 blends stored for 60 days (aged) without and with the addition of an optimal 4% CA antioxidant. The results showed that adding 4% CA to the B30 blend extended its IPs to 34.5 hours, meeting EN590 standards for FAME blends. Compared to B30–60d, the B30+4CA-60d blend exhibited a 9.4% increase in BTE and a 6.5% decrease in BSFC at a BMEP of 4.15 bar. It has an emission reduction potential of 47.8% for CO, 8% for HC, along with a marginal decrease in NO emissions. Compared to D100, it significantly reduced CO emissions by 37.5%, HC emissions by 8%, and NO emissions by 16.3%. These findings indicate that natural antioxidants effectively inhibit free radical formation and maintain biodiesel quality over extended storage on par with synthetic antioxidants. This finding is significant as it maintains engine performance and addresses global energy and environmental concerns.

中文翻译：

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农业废弃物中的精油作为抗氧化剂对 CI 发动机生物柴油长期储存稳定性的影响：新鲜和陈化评估

本研究旨在利用 Rancimat 方法 (EN14112) 改善 Prosopis juliflora 甲酯 (PJME) 的氧化和储存稳定性。农业废物衍生精油 (AWEO)，如柑橘 (CA)、姜黄 (CL) 和赤桉 (EC)，与常用的合成抗氧化剂 TBHQ 一起用作天然抗氧化剂。抗氧化剂的浓度范围为 0% 至 4%（生物柴油的 v/v%）。结果表明，在原始 PJME 中添加 4% CA 将诱导期 (IP) 从 2.64 小时延长至 60 天结束时的 11.2 小时，符合 EN14214 标准并表现出最高的抗氧化活性。 TBHQ 在较低浓度下效果较差；然而，它与更高浓度的 CL 相当。当 PJME 含量为 4% TBHQ 时，15 天、30 天和 45 天存储结束时的 IP 分别为 9.9、8.8 和 8.1 小时。此外，这项研究独特地比较了使用新鲜 B30 混合物、储存 60 天（陈化）的 CI 发动机的性能和排放，不添加和添加最佳 4% CA 抗氧化剂。结果表明，在 B30 共混物中添加 4% CA 后，其 IP 时间延长至 34.5 小时，符合 FAME 共混物的 EN590 标准。与 B30–60d 相比，B30+4CA-60d 共混物在 BMEP 为 4.15 bar 时，BTE 增加了 9.4%，BSFC 减少了 6.5%。它的 CO 排放潜力为 47.8%，HC 排放潜力为 8%，同时 NO 排放量略有减少。与D100相比，CO排放量显着减少37.5%，HC排放量减少8%，NO排放量减少16.3%。这些发现表明，天然抗氧化剂可以有效抑制自由基的形成，并在长期储存过程中保持生物柴油的质量，与合成抗氧化剂相当。这一发现意义重大，因为它可以保持发动机性能并解决全球能源和环境问题。