Institute of Mechanical Process Engineering and Mineral Processing

Freiberg, Germany

Institute of Mechanical Process Engineering and Mineral Processing

Freiberg, Germany
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Knupfer P.,Institute of Mechanical Process Engineering and Mineral Processing | Ditscherlein L.,Institute of Mechanical Process Engineering and Mineral Processing | Peuker U.A.,Institute of Mechanical Process Engineering and Mineral Processing
Colloids and Surfaces A: Physicochemical and Engineering Aspects | Year: 2017

Agglomeration of solid particles in aqueous liquid flows is generally influenced by the appropriate interacting forces. Between hydrophobic particles, these forces are dramatically increased compared to van der Waals forces due to the formation of capillary bridges, caused by nanobubbles located at the particle surface. In this study, both hydrophobic and hydrophilic agglomerates were generated in water with an agglomeration setup based on a stirred tank reactor. Variating the shear rate leads to different agglomeration sizes and provides information about the agglomerate strength. In principle, both stability and size of the hydrophobic agglomerates are larger than the hydrophilic ones. The presence of the nanobubbles is proved by applying atomic force microscopy to the particle surface. © 2017 Elsevier B.V.


Darwish M.S.A.,Egyptian Petroleum Research Institute | Kunz U.,Institute of Chemical Process Engineering | Peuker U.,Institute of Mechanical Process Engineering and Mineral Processing
Journal of Applied Polymer Science | Year: 2013

Platinum (Pt) nanoparticles show high activity as catalysts in various chemical reactions. The control of the morphology of Pt nanostructures can provide an opportunity to improve their catalytic properties. The preparation of Pt-loaded iron-oxide polyvinylbenzyl chloride nanocomposites was done in several stages: first by the formation of the core consisting of magnetite nanoparticles and second by the polymerization of vinylbenzyl chloride in the presence of the magnetic core particles. The third step is the amination of the chlorine group with ammonia, which leads to an ion exchange resin. Then, the Pt precursor (H2PtCl6) is attached by ion exchange. Finally, the Pt ions are reduced to Pt metal with NaBH4. The obtained material can be dispersed easily and be used as a catalyst which can be separated after the reaction by magnetic fields. Characterization of the resulting metallic nanocomposites is evaluated by atomic absorption spectroscopy, thermal gravimetric analysis, transmission electron microscopy, infrared spectroscopy, and gas chromatography. The activity of Pt at magnetic core/shell nanocomposites was measured for the reduction reaction of cinnamaldehyde to cinnamyl alcohol. © 2012 Wiley Periodicals, Inc.


Darwish M.S.A.,Institute of Chemical Process Engineering | MacHunsky S.,Institute of Mechanical Process Engineering and Mineral Processing | Peuker U.,Institute of Mechanical Process Engineering and Mineral Processing | Kunz U.,Institute of Chemical Process Engineering | Turek T.,Institute of Chemical Process Engineering
Journal of Polymer Research | Year: 2011

Magnetic composite particles with a magnetic core consisting of superparamagnetic iron oxide and a cover layer of hydrophobic polyvinylbenzylchloride are described. The magnetite was prepared by precipitation starting with mixed iron II and iron III salts and coating of the solid with oleic acid. The coating is conducted via the liquid-liquid phase transfer. Thereby oleic acid adsorbed on the magnetite surface. In a second step the oleic acid treated magnetite was coated with polyvinylbenzylchloride in a miniemulsion polymerization to get a protective layer. The obtained magnetite core-shell nano-composites with chlorine functionality were characterized by different methods: particle size measurement, acid treatment, iron content, morphology and elemental profiles across the composite particles diameter. The test result reveals the binding of the iron oxide inside the composites which can be also recognize in TEM pictures. © 2010 Springer Science+Business Media B.V.


Heuzeroth F.,Institute of Mechanical Process Engineering and Mineral Processing | Fritzsche J.,Institute of Mechanical Process Engineering and Mineral Processing | Peuker U.A.,Institute of Mechanical Process Engineering and Mineral Processing
Particuology | Year: 2014

Deep bed filtration in aqueous media is a well-known process for solid-liquid separation. However, the use of deep bed filtration for the purification of metal melts is a relatively new field of application. In particular, the separation mechanism of metal melts filtration is a new area for investigation. The current paper aims at examining the influence of wetting on the filtration efficiency of ceramic foam filters that is an important feature of the metal melts filtration process. A model system was designed using water and alumina particles (<200. μm). The particles and filter medium were coated to model poor wetting. Thus, examination of the influence of wetting on the adhesion energy and filtration performance was possible. Furthermore, the effect of fluid velocity was studied. To this end, the experiments were carried out under atmospheric conditions and at 20. °C. The findings showed that poor wetting between the fluid and solid phase significantly increased the filtration efficiency. © 2014.

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