Abstract The aim of this study was to establish a phenomenological model capable of describing the mass transfer and kinetic effects of the in situ transesterification of Acutodesmus obliquus microalgae dry biomass. This model was developed considering the following: homogeneous cell volume and composition; cells agglomerate forming clusters during in situ reaction; the cluster is considered to be formed of internal and external regions; the species concentration in the cluster is described considering multicomponent Langmuir isotherm model; the fatty acids diffusion inside clusters is described by Fick’s Law; mass transfer of the fatty acids between external solid and bulk phases is governed by convection; and reaction occurs homogenously in the bulk phase. Results show that the proposed model fits the experimental data and adequately describes the reaction kinetics and mass transfers between bulk and external solid phases as well as from internal to external solid phases. It was verified that ester production is higher in the initial period of reaction due to the greater availability of lipids, tending to achieve a maximum over time. The mass transfer coefficients values suggest that the alcohol moves towards the solid phase more hardly than the fatty acids are extracted to the bulk phase. Moreover, the Langmuir constants show that the alcohol has higher adsorption strength in the biomass than the esters.

中文翻译：

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Acutodesmus obliquus 微藻原位酯交换的现象学模型

摘要 本研究的目的是建立一个现象学模型，该模型能够描述斜纹夜蛾微藻干生物质原位酯交换的传质和动力学效应。该模型的开发考虑到以下因素：均质的细胞体积和组成；细胞在原位反应过程中聚集形成簇；集群被认为由内部和外部区域组成；考虑多组分朗缪尔等温线模型来描述簇中的物种浓度；脂肪酸在簇内的扩散由菲克定律描述；外部固相和本体相之间脂肪酸的传质受对流控制；并且反应在本体相中均匀发生。结果表明，所提出的模型符合实验数据，并充分描述了本体和外部固相之间以及从内部固相到外部固相的反应动力学和传质。经证实，由于脂质的可用性更高，在反应的初始阶段酯产量更高，随着时间的推移趋于达到最大值。传质系数值表明醇向固相移动比脂肪酸被提取到本体相更难。此外，朗缪尔常数表明，醇在生物质中的吸附强度高于酯。经证实，由于脂质的可用性更高，在反应的初始阶段酯产量更高，随着时间的推移趋于达到最大值。传质系数值表明醇向固相移动比脂肪酸被提取到本体相更难。此外，朗缪尔常数表明，醇在生物质中的吸附强度高于酯。经证实，由于脂质的可用性更高，在反应的初始阶段酯产量更高，随着时间的推移趋于达到最大值。传质系数值表明醇向固相移动比脂肪酸被提取到本体相更难。此外，朗缪尔常数表明，醇在生物质中的吸附强度高于酯。