Rückgewinnung von Metallen aus niedrigkonzentrierten Lösungen

Recycling of metals from low concentrated solutions. A review is given of processes used for the separation of metals from aqueous solutions, especially low concentration waste waters. Purification processes for waste water used only to reach values set by law are compared with processes that allow recovery of metals. Precipitation with and without additives, adsorption, processes with ion exchange resins, solvent extraction and membrane processes, especially liquid membrane permeation, are described. As a result of these considerations, a qualitative comparison of all the described processes becomes possible. For the separation of zinc from a waste water stream, a special economic comparison is also shown between precipitation processes and the liquid membrane permeation process. Finally, the latest developments in the fields of solvent extraction and liquid membrane permeation are discussed.     

Keramische Membran zur Wasserabtrennung aus Lösungsmitteln

Novel hydrophilic SiO_x modified alumina membranes with high separation factors and flux rates have been prepared for the separation of water from organic solvents. The membranes are prepared by the deposition of SiO_x networks inside the γ‐Al₂O₃ layer of a commercial ultrafiltration membrane by hydrolysis of tetraethylorthosilicate in autoclaves at 250°C. The transport resistance of the individual membrane layers to the permeation flux are described by a model. The membranes are stable towards solvents up to at least 150°C. Pervaporation studies show that water can be separated from solvents like acetonitrile, tetrahydrofuran, 2‐isopropanol, ethanol, dimethylsulfoxide, dimethylformamide, phenol. The separation performance of the membranes allows their use in technical separation processes, especially for the remove of water.     

Technische Lösungen zur Schälung von Ölsaaten

Technical Solutions for the Dehulling of Oil Seeds The generation of a kernel-hull-mixture, its fractionation and the hull- seperation is elaborated for the example of sunflower seed. The use of electro-separation represents a new alternative to the traditional technology of air-sifting. The new technology enables us to make significant reductions of electric power consumption and production area. The major advantages of the SKET-solution and a prospective view of the application for further oil seeds are pointed out.     

Verfahren zur Mikrofiltration von Prozeßlösungen und ihre Anwendungen

Approaches to microfiltration of process solutions and its application. Particles and microorganisms in the site range of 0.02 to 10 μm are reliably removed by microfiltration processes. Microporous polymer membranes are suitable as filter medium. The particles are then separated mainly on the exterior surface (surface filtration). This leads to formation of a covering layer on the membrane and a relatively high hydraulic resistance. Dynamic filtration processes counteract covering layer formation. The most widely developed technique is crossflow microfiltration, in which the membrane is subject to continuous flow of the suspension. The development of large membrane units fulfils requirements for large-scale industrial application of crossflow microfiltration.