Liquid-liquid Extraction
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What is extraction?
One option for selective and product-friendly processing is liquid-liquid extraction. This low-energy separation process can reduce energy consumption and CO2 emissions compared to conventional separation operations such as rectification. In this process, the component to be separated is extracted from the feed phase using a suitable solvent. For example, temperature-sensitive products can be separated in an energy-efficient manner. Furthermore, extraction in the context of in-situ product separation can also be coupled directly to a reaction so that the yield and selectivity of the reaction are positively influenced.
Challenges extraction today (What is our research?)
The increasing use of bio-based raw materials and the implementation of recycling processes in the circular economy pose new challenges for separation technology. Recycling residual material streams requires high robustness and selectivity of separation processes at low production costs. Products from biotechnological syntheses are also often temperature sensitive, have high boiling points, or are present in low concentrations.
However, the effects of biotechnological accompanying components and minor components in the recycling streams (salts, proteins, particles) on the extraction have been insufficiently studied so far. Another challenge is transferring knowledge in fluid dynamics and mass transport from the laboratory to the technical scale. Therefore, our research groups (ExSys, DiS²Co and LLCol) investigate model-technically and experimentally the phenomena of novel extraction systems from single droplets to apparatuses on a technical scale.
Our Research Groups
Extraction Systems (ExSys)
The goal of our "Extraction Systems" team is to develop innovative extraction systems for processing products from the fields of biotechnology and battery and plastics recycling. In doing so, we investigate the complex interrelationships and fundamental phenomena of two-phase liquid-liquid systems characterized by many interacting components.
To this end, we characterize mass transport in special test rigs and develop measurement and evaluation methods. On the other hand, we research extraction processes that are relevant to biotechnological processes and recycling management. For example, we work on reactive extraction to process biotechnologically produced organic acids or recover rare earths. These systems are investigated using statistical methods (e.g., design of experiments) and described with models.
Through this more profound understanding of the physical and phenomenological relationships, tailor-made extraction processes can be developed for individual issues in biotechnology and recycling (plastics, batteries, or textiles). At the same time, this also enables the development of new methods for process intensification (e.g., in-situ extraction) and avoidance of side streams (e.g., electrochemically induced extraction).
Current research interests include:
- Extraction of biotechnological products
- Extraction of metal ions
- Extraction of polymer building blocks
- Investigation of new solvents
- Electrochemically induced extraction
- Direct product separation by extraction (in situ extraction)
Experimental and simulative student research projects and theses are regularly available in the abovementioned areas. Please contact the contact person (William von Westarp) or look at the advertised theses at the AVT.FVT.
Dispersion, Sedimentation, Species Transport & Coalescence (DiS²Co)
The goal of our team "Dispersion, Sedimentation, Species Transport & Coalescence" is the detailed experimental investigation of the individual phenomena in the dispersion and phase separation process, the model-based description of these phenomena and the transfer of the developed modeling methods to the technical scale.
For this purpose, we characterize dispersion, sedimentation, mass transport, and coalescence phenomena in two-phase liquid-liquid systems on special test rigs, both on laboratory and pilot plant scale. For this purpose, we use self-developed automated measurement techniques and AI-based evaluation methods to observe phenomena on micro and macro scales. For example, we use object recognition software to evaluate droplet size distribution, droplet rise, or coalescence processes on real substance systems online. The knowledge gained is then used to understand these phenomena and to develop suitable modeling methods for complex systems. With the help of validation experiments on a technical scale, it is possible to verify the predictive accuracy and technical applicability of the developed modeling methods and build the bridge to application.
Current research interests include:
- Fluid dynamics of single droplets with mass transfer
- Dispersion and phase separation behavior of real substance systems
- Microgel-assisted extraction
- Soft sensor development and control for a liquid-liquid separator in a pilot plant
- Numerical simulation of multiphase phenomena by CFD
Experimental and simulative student research projects and theses are regularly available in the abovementioned areas. Please contact the contact person (Song Zhai) or look at the advertised theses at the AVT.FVT.
Liquid-Liquid Columns (LLCol)
The goal of the "Liquid-Liquid Columns" team is the design and efficient operation of columns on an industrial scale. For this purpose, we develop models which we parameterize and validate in laboratory and pilot plant scale experiments.
The liquid-liquid extraction process is often carried out in co-current or countercurrent columns. In order to ensure an optimal extraction or extractive reaction process, the extraction agent, the column dimensions, internals geometries, and energy input must be coordinated.
For this reason, intensive research is being carried out on developing models for the simulation of extraction and reactive extraction columns. In particular, the complex interplay of fluid dynamic phenomena, mass transport, and, if necessary, reaction kinetics in the column must be considered. In order to develop new submodels for various phenomena and to validate the overall models, experiments are also carried out on pilot-scale columns. Attention is also paid to integrating the column into the overall process, both by simulative consideration of the overall process and by experimental interconnection of the different process steps in the biorefinery. In order to develop tailor-made models for our respective applications, the level of detail ranges from simple rate models to complex CFD-based models. In order to improve the accuracy and performance of the models, machine learning approaches are also becoming increasingly important.
Current research interests include:
- Model-based solvent screening and apparatus design for extraction processes
- Experimental investigation on (high pressure) extraction columns
- Characterization and optimization of column internals
- Online condition diagnostics of liquid-liquid extraction columns (Industry 4.0)
- Thermodynamic characterization of complex recycling mixtures in rectification columns
Experimental and simulative student research projects and theses are regularly available in the abovementioned areas. Please contact the contact person (Lukas Polte) or look at the advertised theses at the AVT.FVT.