Department of Mechanical and Thermal Process Engineering, Faculty of Chemical Engineering and Technology, University of Zagreb, Zagreb, Croatia.
Department of Thermodynamics, Mechanical Engineering and Energy, Faculty of Chemical Engineering and Technology, University of Zagreb, Zagreb, Croatia.
J Environ Manage. 2022 Aug 15;316:115222. doi: 10.1016/j.jenvman.2022.115222. Epub 2022 May 8.
Biodiesel produced from waste feedstocks can play a significant role in fighting climate change, improperly disposed waste and growing energy demand. Waste feedstocks such as used cooking oil have a great potential for energy production. However, they often have to be purified from free fatty acids prior to biodiesel production. Extractive deacidification with deep eutectic solvents is a promising alternative to conventional purification methods. To evaluate the process of extractive deacidification of waste cooking oil, a full set of physical, hydrodynamic and kinetic data were experimentally determined on a laboratory scale. Hydrodynamic and kinetic experiments were performed in three geometrically similar jacketed agitated vessels. Vessels were equipped with axial flow impeller (four pitched blade impeller). Physical properties (density, viscosity and surface tension) were experimentally determined. Preliminary hydrodynamic experiments involved several model systems without mass transfer. As a result, correlation between power number and Reynolds number as well as scale-up criterion was developed. Obtained dependencies were correlated with the physical properties. Mixing intensity for achieving complete dispersion was determined. Second stage of investigation involved two sets of experiments, hydrodynamic and kinetic, with interphase mass transfer (the extraction of free fatty acids from waste cooking oil with deep eutectic solvent, potassium carbonate:ethylene glycol, 1:10). Obtained results enabled understanding interphase mass transfer and prediction of mass transfer coefficient from the derived dimensionless correlations. The values of volumetric mass transfer coefficients were smaller for the dispersed phase, indicating that the prevailing mass transfer resistance was within the droplets. The working hypothesis was that the same process result should be achieved at the same dispersion rate, and that hypothesis was confirmed - at all scales extraction efficiency was 97.9 ± 0.1%.
从废饲料中生产的生物柴油可以在应对气候变化、不当处理的废物和不断增长的能源需求方面发挥重要作用。废饲料，如用过的食用油，具有很大的能源生产潜力。然而，在生产生物柴油之前，它们通常需要从游离脂肪酸中进行纯化。与传统的纯化方法相比，深共晶溶剂的萃取脱酸是一种很有前途的替代方法。为了评估从废食用油中进行萃取脱酸的过程，在实验室规模上对一组完整的物理、流体动力学和动力学数据进行了实验测定。在三个几何相似的夹套搅拌容器中进行了流体动力学和动力学实验。容器配备了轴向流叶轮（四个斜叶叶轮）。实验测定了物理性质（密度、粘度和表面张力）。初步的流体动力学实验涉及几个没有传质的模型系统。结果，开发了功率数与雷诺数之间的相关性以及放大标准。获得的相关性与物理性质相关联。确定了达到完全分散所需的混合强度。第二阶段的研究涉及两组实验，即带有相间传质的流体动力学和动力学实验（用深共晶溶剂（碳酸钾：乙二醇，1：10）从废食用油中萃取游离脂肪酸）。获得的结果使我们能够理解相间传质，并从推导出的无量纲相关性中预测传质系数。对于分散相，体积传质系数的值较小，这表明主要的传质阻力在液滴内。工作假设是，在相同的分散速率下，应该达到相同的过程结果，这一假设得到了证实——在所有规模下，萃取效率均为 97.9±0.1%。
