Fine bubbles for biocatalytic processes: Microscale phenomena and novel applications

生物转化，其中一个反应物通过气相提供，特别是在氧化的情况下，仍然是一个挑战。通过对酶体系的流体力学、传质效应和反应动力学的研究，研究了直径小于100µm的微气泡对酶反应的曝气作用。然而，关于在溶解的细小气泡的气液界面上发生的局部过程的基本科学问题仍然是有针对性的。如果细小的气泡和表面固定化的酶之间的相互作用得到解决，这一点就更加重要，特别是在人们越来越关注规整填料作为酶的载体材料的背景下。随着气泡直径的减小，界面处的局部传质速率和氧浓度梯度将受到拉普拉斯压力的强烈影响。对于传质受限的酶反应，这种传质增强以及酶与气液界面之间的相互作用是影响反应有效性的主要方面。利用激光诱导荧光(LIF)测量可以研究局部传质现象。在这些测量的帮助下，将分析酶在微泡曝气中比传统曝气更稳定的效果，如先前项目中所展示的那样。在此背景下，为了更好地了解酶变性的作用机理，将对浓度边界层条件进行研究。

Biotransformations, where one of the reactants is supplied via the gas phase, especially in the case of oxidations, are still a challenge. The aeration of enzymatic reactions using fine bubbles, whose diameters are less than 100 µm, has been investigated by focusing on hydrodynamics and mass transfer effects as well as reaction kinetics of enzymatic systems. However, the fundamental scientific questions regarding the local processes taking place at the gas-liquid interface of a dissolving fine bubble are still to be targeted. This is even more important, if the interaction between a fine bubble and an immobilized enzyme on a surface is addressed, especially, on the background of increasing attention to structured packings as carrier materials for enzymes. The local mass transfer rate and oxygen concentration gradient at the interface is expected to be strongly affected by the Laplace pressure with decreasing bubble diameter. For mass transfer limited enzymatic reactions this mass transfer enhancement and the interaction between the enzymes and the gas-liquid interface are central aspects influencing the effectivity of the reaction. Using Laser Induced Fluorescence (LIF) measurements local mass transfer phenomena can be studied. With the help of these measurements the effect that enzymes are more stable during fine bubble aeration compared to conventional aeration, as demonstrated in the predecessor project, will be analyzed. In this context, investigation of the concentration boundary layer conditions on enzyme denaturation will be carried out for a better understanding of the acting mechanisms.