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Continuous processes for the formation of nanoparticles
Sibylle von Bomhard, Scientist, Fraunhofer ICT-IMM
In the past decade, a growing number of different types of inorganic and polymeric nanomaterials with novel properties and unique advantages have been developed and applied in a multitude of applications. Therefore, there is a growing interest in the scale up for the production of engineered nanoparticles with controlled and adjustable size, composition, morphology, and surface functionalization.
For the design of sustainable continuous processes it is important to not only consider the production of the nanoparticles but also the purification and downstream processing as well as the integration of online analytics in combination with a process control system.
Several continuous processes for the production of inorganic nanoparticles e.g. silica and iron oxides were designed and realized.
Regarding organic materials, a continuous method combining the miniemulsion technique with a highly efficient solvent evaporation was established for the formation of various kinds of polymeric particles and the encapsulation of a wide range of cargos. Depending on the polymer composition, experimental parameters and the presence of inorganic substances, different properties and morphologies can be accomplished.
Moreover, the implementation of online characterization paired with a process control system is exemplified by the laboratory scale unit for the production of highly defined quantum dots.
Heterogeneous Organic Photoredox-Catalysis in a Triphasic Flow System
Bartholomäus Pieber, Assistant Professor, Max Planck Institute of Colloids and Interfaces
The utilization of light to accelerate a chemical reaction is undoubtedly one of the most promising and sustainable fields in modern chemistry. Particularly, photoredox catalysis using the visible light spectrum has recently gained widespread recognition as a powerful tool for organic synthesis. Unfortunately, its applicability is often limited by the low irradiation efficiency in batch and the utilization of often expensive homogeneous transition metal catalysts which require time consuming separation procedures. A combination of continuous flow processing and heterogeneous catalysis can potentially address these drawbacks. However, examples of heterogeneous photocatalysis in continuous flow devices are relatively rare in the scientific literature. This is most likely due the lack of a general, easily accessible flow reactor and a limited number of versatile heterogeneous photoredox catalysts for selective organic transformations.
In this presentation a simple and robust reactor design for efficient heterogeneous photoredox catalysis will be discussed. Moreover, a powerful polymeric material which can be easily prepared from cheap organic starting materials will be introduced as an alternative for common homogeneous for visible-light photoredox catalysts.
3D Printed Advanced Mesoscale Flow Reactor for Synthesis of Silver Nanoparticles
obinna okafor, PhD student, University of nottingham
The implementation of advanced reactor engineering concepts employing additive manufacturing is demonstrated. The design and manufacturing of miniaturised continuous flow oscillatory baffled reactors (mCOBR) employing low cost stereolithography based 3D printing is reported for the first time. Residence time distribution experiments have been employed to demonstrate that these small scale reactors offer improved mixing conditions at a millimetre scale, when compared to tubular reactors. Nearly monodisperse silver nanoparticles have been synthesised employing mCOBR, showing higher temporal stability and superior control over particle size distribution than tubular flow reactors.
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