The sufficient provision of oxygen is mandatory for enzymatic oxidations in aqueous solution, however, in process optimization this still is a bottleneck that cannot be overcome with the established methods of macrobubble aeration. Providing higher mass transfer performance through microbubble aerators, inefficient aeration can be overcome or improved. Investigating the mass transport performance in a model protein solution, the microbubble aeration results in higher kL a values related to the applied airstream in comparison with macrobubble aeration. Comparing the aerators at identical kL a of 160 and 60 1/h, the microbubble aeration is resulting in 25 and 44 times enhanced gas utility compared with aeration with macrobubbles. To prove the feasibility of microbubbles in biocatalysis, the productivity of a glucose oxidase catalyzed biotransformation is compared with macrobubble aeration as well as the gas-saving potential. In contrast to the expectation that the same productivities are achieved at identically applied kL a, microbubble aeration increased the gluconic acid productivity by 32% and resulted in 41.6 times higher oxygen utilization. The observed advantages of microbubble aeration are based on the large volume-specific interfacial area combined with a prolonged residence time, which results in a high mass transfer performance, less enzyme deactivation by foam formation, and reduced gas consumption. This makes microbubble aerators favorable for application in biocatalysis.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/bit.27556

Comparative investigation of fine bubble and macrobubble aeration on gas utility and biotransformation productivity.

The present experimental study aimed to investigate the performance and characteristics of the dissolved oxygen in water aeration under the variations of the gap between the air nozzle and the outlet of new developed swirl flow type of the microbubble generator (MBG). The present experimental investigation, the flow rates of both of air (QG) and the water (QL) were determined in the range of (0.1–0.8) l/min and (20–50) l/min, respectively. The shadow photographic technique was used to extract the results of a high-speed camera of microbubbles images to find the bubbles size and their distribution. The dynamic physical absorption model was used to measure the coefficient of the oxygen volumetric mass transfer (KLa). The results show that the microbubbles size (diameter average davg and peak PDF curve) produced by the swirl MBG type was smaller and more uniform than that of produced by orifice MBG type. Next, the characteristics of the microbubbles were investigated by the combinations of QG, QL and the gap between the air nozzle and the outlet of the microbubble generator. Here, it is noticed that the higher the gas flow rate, the higher the average diameter of the bubble. The higher the liquid flow rate, the lower the average diameter of the bubble. Furthermore, the QL increases with KLa. Finally, the empirical correlations to predict the KLa, davg and the log-normal distribution of the bubble diameter were proposed. 

Hydrodynamic characteristics of the microbubble dissolution in liquid using the swirl flow type of microbubble generator

O2-dependent biocatalysts are among the most studied and used biocatalysts on the lab scale. Their diversity and functional versatility make them very attractive for the sustainable industrial synthesis of a variety of compounds. However, their dependence on O2 implies numerous technical and economic challenges. The low O2 transfer rates, the low solubility of O2, and the supply of O2, currently limit the applicability of O2-dependent enzymes at the industrial scale. In this mini-review, we summarize the latest engineering approaches that address and partially solve the issues related to O2-dependent enzymes. 

Engineering approaches for O2-dependent Enzymes

Enhanced Enzyme Stability and Gas Utilization by Microbubble Aeration Appling Microporous Aerators

Accurate knowledge of volumetric oxygen mass transfer coefficients in multiphase systems is important for successfully designing and efficient operation of process plants. As a result, a large number of papers on the determination of volumetric mass transfer coefficients k L a have been published in the literature. The dynamic degassing method is probably the most common method for determining the volumetric mass transfer coefficient. However, little work is known on the influence of countercurrent diffusion effects, arising from further dissolved components, on the volumetric mass transfer coefficient. For this reason, the effect of countercurrent diffusion is investigated in the present work by using different stripping gases to determine the volumetric oxygen mass transfer coefficient. Furthermore, the effect of counterdiffusion is investigated for both conventional aeration and aeration with microbubbles. The present work shows that the choice of stripping gas has a decisive influence on the determination of the volumetric oxygen mass transfer coefficient. Moreover, it can be shown that this effect is directly proportional to the solubility of the stripping gas in the aqueous phase. Simultaneous measurements of bubble size distributions allow determining mass transfer coefficients k L . A model is developed describing the decrease in the mass transfer coefficient as a function of the solubility of the stripping gas. Furthermore, it can be shown that for the experimental determination of volumetric oxygen mass transfer coefficients, the choice of stripping gas should be adapted to secondary gas types occurring within real processes achieving a better comparability.

Influence of counterdiffusion effects on mass transfer coefficients in stirred tank reactors

Hydrodynamic and Mass Transfer Correlation in a Microbubble Aerated Stirred Tank Reactor

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

Michael Schlueter

Author Tools

Chat about Author

Papers

Hydrodynamic and Mass Transfer Correlation in a Microbubble Aerated Stirred Tank Reactor