Abtrennung organischer Dämpfe mit Membranen

Removal of Organic Vapours by Membranes Even on consistent use of productionoriented environmental protection measures it still proves impossible to avoid the formation of solvent-containing gaseous effluents in many production processes. Thus the reduction of emissions by purification of solventcontaining process and exhaust gas streams is still a highly topical matter. Thermal, catalytic, or biological oxidation processes leading to destruction of the organic solvents should only be used when solvent recovery is impossible. Preference should always be given to those processes which protect resources by permitting recovery of solvent. Substantial advances in the area of membrane technology during the past ten years mean that gas permeation now constitutes an interesting alternative to conventional processes. Combination of a membrane separation stage with direct or indirect condensation gives a hybrid process permitting gentle and contamination-free recovery of organic components. This article briefly summarises the fundamentals of permeation of gas/vapour mixtures through polymer membranes.     

Der gegenwärtige Stand der Trenntechnik mit Membranen

Current Status of Membrane Technology Separation using membranes is yet to become a common technical process. The reasons for this include inadequate membranes and economic aspects. Since the basic idea behind such a process offers great advantages, efforts are being made to overcome the difficulties encountered.     

Neue Entwicklungen in der Flüssigmembranpermeation mit gestützten Membranen

In a time of rising raw material prices und raw material shortage topics like recycling of heavy metal ions from aqueous solutions get in the focus of the public. Aim of the presented work is the development of a new apparatus design for liquid membrane permeation with support layers. The investigations are carried out in view of heavy metal recycling.     

Stofftrennung durch Membranen

Separation by membranes . The paper reviews membrane processes in general, excluding the electro-membrane processes. The authors' aim is to discuss the aspects common to all membrane processes as well as the essential differences between them. The following processes will be examined: Reverse osmosis, ultrafiltration, gas permeation through porous or diffusion type membranes, pervaporation and liquid membrane techniques. In liquid systems, mass transport at the membrane surface proves to be the limiting factor. Conditions on the permeate side tend to influence flux and quality of the permeate only when a considerable pressure drop occurs. A typical example is that of hollow-fiber modules. It is shown how the permeability and dimensions of the membrane require selective adjustment in order to establish maximum flux.     

Membranen in der Verfahrenstechnik

Membranes in chemical engineering . In the last 10 years membranes and membrane processes have evolved from a useful laboratory tool to an industrial product of significant technical and commercial impact. In some applications membrane processes have today not only replaced some conventional separation procedures in the chemical process industry, because they are often more economical and yield better quality products, but they have also successfully been utilized to solve mass separation problems where conventional procedures failed or are too expensive. This contribution discusses the state of the art of membranes and membrane processes as well as their major applications, with the main emphasis being placed on more recent developments.     

Keramische Membranen in der Membrandestillation

TiO₂ membranes were successfully rendered hydrophobic (modified with perfluoroalkyl silanes) and evaluated by liquid entry pressure (LEP) measurements and membrane distillation (MD) tests. It was shown that the LEP is strongly depended on the pore size of the membranes and the feed composition. The obtained permeate fluxes were highest in vacuum MD. None of the membranes showed any sign of wetting during the experiments and salt retentions greater than 99.9 % were recorded and permeate qualities lower than 2 µS cm^?1 were achieved in air gap MD and vacuum MD.