@article{KempinDrews, author = {Kempin, Maresa Vivien and Drews, Anja}, title = {What Governs Pickering Emulsion Properties During Preparation via Batch Rotor-Stator Homogenizers? }, series = {Chemie Ingenieur Technik}, volume = {93}, journal = {Chemie Ingenieur Technik}, number = {1-2}, doi = {10.1002/cite.202000130}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-14628}, pages = {311 -- 317}, abstract = {Pickering emulsions have received increasing interest in many fields of application recently. In designing Pickering emulsion properties, focus is typically laid on composition whereas the preparation process as another possible leverage is not considered in detail. Here, Pickering emulsions of constant composition were prepared using two dispersing heads of a rotor-stator homogenizer and compared in terms of Sauter mean diameters and rheology. It was found that the ratio of tip speed and gap width between rotor and stator is a better correlating parameter than tip speed only.}, language = {en} } @article{RusliGrabowskiDrewsetal., author = {Rusli, Sherly and Grabowski, Janna and Drews, Anja and Kraume, Matthias}, title = {A Multi-Scale Approach to Modeling the Interfacial Reaction Kinetics of Lipases with Emphasis on Enzyme Adsorption at Water-Oil Interfaces}, series = {Processes}, volume = {8}, journal = {Processes}, number = {9}, publisher = {MDPI}, issn = {2227-9717}, doi = {10.3390/pr8091082}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-14441}, pages = {20}, language = {en} } @article{KempinDrews, author = {Kempin, Maresa Vivien and Drews, Anja}, title = {Organic Solvent Nanofiltration of Water-in-Oil Pickering Emulsions—What Influences Permeability?}, series = {Membranes}, volume = {11}, journal = {Membranes}, number = {11}, editor = {Samhaber, Wolfgang and Rezaei, Mohammad}, publisher = {MDPI}, issn = {2077-0375}, doi = {10.3390/membranes11110864}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-15297}, pages = {1 -- 16}, abstract = {Pickering emulsions (PEs) have received increasing interest for their application in catalytic multiphase reactions. Organic solvent nanofiltration of PEs was shown to be a promising procedure for efficient and effective catalyst recycling. In this work, a systematic parameter study to identify the main influencing parameters on PE filtration was conducted for a large variety of PE compositions for the first time. In addition to temperature, only the type of organic solvent significantly influenced the filtration performance, which could be mathematically modeled via a combination of the solution-diffusion and the resistance in the series model. Particle type and concentration, dispersed phase fraction and the presence of reaction (by-)products did not show any significant impact on the permeability. The stirrer speed only became important when emulsions stabilized by particles without the tendency to form 3D network structures were filtered in long-term filtration experiments. These results pave the way towards the application of PE membrane filtration for catalyst recovery in continuous liquid/liquid multiphase reactions and enable broad operation windows. As the mechanical separation of PEs was shown to be a very robust process, the emulsion composition can now be tuned to meet the needs of the reaction without any (significant) loss in filtration performance.}, subject = {-}, language = {en} } @article{SeilerLoidoltKrügervonKlitzingetal., author = {Seiler, Maximilian and Loidolt-Kr{\"u}ger, Maria and von Klitzing, Regine and Drews, Anja}, title = {Effect of pH and Particle Charge on the Interfacial Properties of Biocatalytic Pickering EmulsionsWhere Are the Enzymes Located?}, series = {Langmuir}, volume = {41}, journal = {Langmuir}, number = {37}, publisher = {American Chemical Society}, issn = {0743-7463}, doi = {10.1021/acs.langmuir.5c02459}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:523-21539}, pages = {25264 -- 25276}, abstract = {Pickering emulsions (PEs), where water-in-oil (w/o) droplets are stabilized by nanoparticles (NPs), offer a promising platform for biocatalysis by providing a large interfacial area crucial for efficient substrate conversion. While several lipase catalyzed reactions in PEs have been demonstrated, the exact interfacial structure is unknown. This study focuses on the interfacial network formed by NPs and Candida rugosa lipase (CRL) at the octanol/water-interface by varying pH and NP charge. By applying different methods, the location of lipases within a PE was identified and the enzyme concentration profile quantified for the first time. Positively charged nanoparticles (NP+) adsorbed at the o/w-interface together with CRL to form a network-structure. The relation between individual and simultaneous adsorption showed a constant value of 0.75 for the investigated pH range. Negatively charged particles (NP-) did not adsorb spontaneously at the negatively charged octanol/water-interface and therefore showed no influence on the enzyme adsorption behavior. Interfacial shear rheology measurements further revealed distinct elastic behavior of the enzyme-particle network due to attractive interactions between positively charged nanoparticles and CRL. This was shown by a 4.4-fold increase in the interfacial storage modulus. In contrast, repulsive interactionseither between CRL and positively charged particles at low pH or with negatively charged particlesdid not enhance the elastic response of CRL at the interface. Confocal laser scanning microscopy of prepared PE droplets showed an interfacial CRL layer thickness of 0.75 μm for NP+ and 0.51 μm for NP-. Using NP+ results in a 30\% higher interfacial enzyme concentration, indicating a more compact layer structure. These insights contribute to optimizing biocatalytic systems using PEs for industrial applications and provide a basis for the quantitative analysis of the interfacial layer in a Pickering emulsion.}, language = {en} }