We previously optimized a conventional two-step process (TSP) for biodiesel production using waste coffee grounds (WCGs). In the present study, a novel process, one-step direct process (OSDP) comprised of lipid extraction and simultaneous transesterification in a reactor, was evaluated for biodiesel production for WCGs, and compared with TSP. Owing to a relatively low free-fatty acid content (2.3%), an alkaline catalyst, NaOH, was readily used in this process. We found that a mixture of methanol and n-hexane was the best combination for the OSDP. Optimization of OSDP was conducted by statistical technique, followed by one-factor-at-a-time and sensitivity analysis techniques. Using these techniques, 10.8% (g-biodiesel/g-WCGs) biodiesel yield was achieved at 3.0 wt% of catalyst relative to WCGs, 3.0 mL methanol/g-WCGs, 4.5 mL n-hexane/g-WCGs, 45°C, and 9 h of reaction time. Compared to the TSP, the OSDP saved methanol and n-hexane requirement by 69.7% and 67.2%, respectively, while the actual biodiesel yields based on the lipid amount in WCGs were similar in both processes. This study showed that the novel OSDP could be a promising alternative to TSP for economic biodiesel production from WCGs.

我们以前针对使用废咖啡渣（WCG）的生物柴油生产优化了传统的两步法（TSP）。在本研究中，评估了一种新工艺，包括脂质提取和反应器中同时酯交换的一步一步直接工艺（OSDP），用于生产WCG的生物柴油，并与TSP进行了比较。由于游离脂肪酸含量较低（2.3％），因此该方法中很容易使用碱性催化剂NaOH。我们发现甲醇和正丁烷的混合物正己烷是OSDP的最佳组合。OSDP的优化是通过统计技术进行的，然后是一次一因素分析和灵敏度分析技术。使用这些技术，10.8％（克-生物柴油/克- WCGs）生物柴油的产率在3.0重量相对于WCGs催化剂的％，3.0毫升甲醇/克- WCGs，4.5毫升实现Ñ正己烷/克- WCGs，45℃ ，以及9小时的反应时间。相较于TSP时，OSDP保存甲醇和Ñ分别69.7％和67.2％，己烷要求，而基于在WCGs脂质量的实际生物柴油产率在这两种方法类似。这项研究表明，新型OSDP可能是WCG生产经济生物柴油的有希望的替代TSP的替代品。