Methode zur Erfassung von Stofftransport an fluiden Phasengrenzflächen

A finite volume‐based approach to capture mass transfer phenomena at moving fluid interfaces is proposed. The approach is capable of describing two‐phase systems containing several transferred components. Two concentration fields are defined for each transferred component, while each field has physical meaning just in one phase. This two‐field approach allows formulation of space‐ and time‐dependent boundary conditions at the interface. The suggested approach is validated with three test cases describing a single droplet in a continuous liquid phase. Purely diffusive mass transfer is captured very well. The simulation results for the moving system are in good agreement with experimental data.     

Stoffverlustminimierte Prozesstechnik – Wann lohnen sich Regeneratoren und Konzentratoren?

Material Loss Minimized Process Technology – When are Concentration and Regeneration Units Efficient? Chemical and electrochemical surface treatment processes such as electroplating, pickling, etching, anodizing etc. are a issue of environmental protection. Such surface modification procedures often have a high consumption of chemicals and produce a lot of waste water and heavy metal wastes. Material loss minimized process technology is the result of system optimization between internal recycling processes and external waste recycling. Cost savings, process safety, quality control and environmental compatibility are aims of the complex task system optimization. Process units for surface treatment (process solution), rinsing, concentration and regeneration, are the main focus of system optimization. In this article the relationship of different process variables are discussed in a summary. The optimum degree of internal recovery of surface treatments process chemicals from the rinsing water concentrate is a key criterion in system optimization.     

Stofftransport in mikro‐ und mesoporösen Materialien

Mass Transfer in Micro‐ and Mesoporous Materials Mass transfer in micro‐ and mesoporous materials is of crucial relevance for their practical application to separation and catalysis, since the mobility of adsorbed molecules ultimately limits the rate of the overall processes. Diffusion, i.e. the irregular thermal motion of the molecules, is the dominating process. Diffusion measurements are therefore indispensable for the evaluation of the quality parameters of porous materials. Being able to directly follow the diffusion path of the molecules, microscopic techniques hold a key position among the various methods of diffusion measurement. Besides their fundamentals, the contribution describes the application of these techniques to the investigation of structure‐mobility relations in zeolites and in mesoporous materials of type MCM‐41. As features of particular technological relevance, the phenomena of correlated diffusion anisotropy, of single‐file diffusion, and of molecular traffic control are discussed in detail.