Chemikalienfreie Bekämpfung von Holzschädlingen durch dielektrische Erwärmung mit Radiowellen und Mikrowellen

Thermal pest control requires long treatment times due to the low thermal conductivity of wood and may lead to the formation of cracks. Here, the thermal treatment with radio waves as well as microwaves has been studied. The direct dielectric heating has the advantage of a good homogeneity. The obtained temperature profiles for radio waves were more homogeneous compared to microwaves. Detailed studies showed that elimination of pests was not related to the application of the electromagnetic field itself, but due to the temperature increase.     

Dielektrische Erwärmung von Zeolithen mittels Radiowellen – Selektivität,thermo‐chromatographischer Puls und Trocknen mit Wasser

Dielectric heating with radio‐frequency energy can be applied for a wide spectrum of dry or moist zeolites. It is possible to homogeneously heat packed beds in technical scale. The energy absorption strongly varies with the zeolite type enabling selective heating of layered arrangements containing different zeolites. The specific effect of water interacting with the structural cations allows establishing pronounced temperature gradients within a packed bed with varying water content. For distinct materials such as zeolite NaY, a coupled water‐temperature pulse moving through the packed bed can be established. Potential applications for such a so‐called thermo‐chromatographic pulse range from adsorptive catalytic off‐gas cleaning to thermal regeneration of zeolites in the context of gas drying.     

Modifizierung von Faseroberflächen durch permanente Fixierung supramolekularer Komponenten,Teil 3: Azakronenether

The fixation of aza crown ether derivatives onto polymer surfaces by suitable functional groups is described. Ligands with hydrophobic substituents may be applied to fibrous polymers using conventional technologies of textile processing. It is illustrated that the fixed cavities do not lose their complexing power. The modified fibres show resistance against biological attack.     

Schälung von Rapssaat durch definierte Verformung Teil II: Untersuchungen zum Schälverhalten

Dehulling of Rapeseed by Definite Deformation, Part II: Investigations on Dehulling Behaviour In continuation of results presented in the earlier communication on the disintegration behaviour of rapeseed, the findings on the disintegration of the seed after deformation in the rolls are reported. With the aim to determine the optimum spacing between the rolls, the extent of disintegration after a single passage at constant spacing is compared with that for passages at varying spacings. If one considers that the seed meat has to be deoiled by percolative extraction, effort should be made to obtain high proportions of coarse particles of the meat. The optimum spacing which ensures high capacity, low recycling, and no thawing of the meat particles is S = 0.6 mm.     

Leistungsvergleich von hocheffektiven Zerstäubern mit thermischer Abscheidung der Matrix für die Analytik korrosiver Proben im Halbmikromaßstab durch ICP-Massenspektrometrie

Comparison of Nebulizer Efficiencies with Thermal Trace-Matrix-Separation for the Analysis of Corrosive Samples by ICP-MS on the Semi-Micro-Scale New, highly efficient aerosole generating techniques such as ultrasonic nebulization (USN), hydraulic high pressure nebulization (HHPN) and Meinhard high efficiency nebulization (HEN) are adapted for the on-line analysis of corrosive samples by ICP-MS. Nebulization efficiencies range from 10 to 60%. A desolvation and condensation assembly is described. It allows on-line thermal trace-matrix separation and ensures reduction of all major acid components (HF, HCl, HNO₃,H₂SO₄, H₃PO₄) and of methanol by 90 to 98%. Non-metals (B, Si, Se, Br, I) are washed out and could not be analyzed in the ng/g range. For 68 other analytes recoveries are 95%. The analyte-matrix ratio is increased by a factor of 5 to 25 and detection limits improved by a factor of 2 to 20. Most polyatomic interferences are reduced. Using this system, HPLC, IC, and other trace-matrix separation techniques developed for ICP-AES can, in many cases, be directly applied to ICP-MS. The selective condensation of acids avoids evaporation and its risk of contamination. The entire assembly fits into the torch box of the VG Plamaquad 2+. The system requires sample volumes of less than 1 mL, which allows applications of semi-micro techniques. The total improvement of the detection limits amounts to a factor of 5 to 100 in the ng-range. All results are compared to standard nebulizers and FIA.     

Schälung von Rapssaat durch definierte Verformung Teil I: Untersuchungen zur Saatanatomie

Dehulling of Rapeseed by Definite Deformation, Part I: Investigations on the Anatomy of the Seed In order to achieve an intensive utilization of high quality rapeseed in the future, an improvement in the quality of rapeseed meal is attempted via dehulling prior to oil extraction for the sake of reduction of its crude fiber content. A method is proposed, by which a well-defined deformation of rapeseed is accomplished within two stationary surfaces. The present communication records the anatomical characteristics of rapeseed. It is shown, that a reproducible disintegration of the seed can be expected if the seed is broken carefully. Various types of disintegration are explained. Using a schematic model, the dehulling of rapeseed in rolls is discussed. In a critical analysis of the problem, the aims and the conditions are summarized.     

Modifizierung von Faseroberflächen durch die permanente Fixierung supramolekularer Komponenten,Teil 1: Grundlagen

A new conception for modification of textile surfaces by permanent fixation of supramolecular components is explained. The principle of selective complexation is illustrated. Cyclodextrins, aza crown ethers, calixarenes, cyclotriveratrylenes and fullerenes are mainly suggested as suitable ligands for that procedure. The chemical structure and the complexation behaviour of the substances are described. Some surface properties which may be obtained with the ligands are especially emphasized.     

Advanced‐TEMKIN Reaktor: Testung von industriellen Schalenkatalysatoren im Labormaßstab

In a variety of reactions in the chemical industry egg‐shell catalysts with a thin active layer are applied, which are often crushed for laboratory testing. The destruction of the shell can be avoided by a special reactor design. The presented Advanced TEMKIN reactor is a further development of the reactor system for testing egg‐shell catalysts in laboratory scale published by Temkin et al. in 1969. It is suitable for kinetic studies as well as for the detailed research of deactivation processes, as is shown on the example of the selective hydrogenation of acetylene.     

Phasengrenzflächen in Blasenströmungen – Teil 3: Koaleszenzhemmung

The first part of this contribution [1] presents the population balances, i.e., balance equations for the numerical density of the bubbles in the individual bubble fractions. They are solved approximately by an analytical approach. There results a straightforward balance equation for the average bubble volume. This equation can be solved analytically for simple fields of flow. For complex fields of flow it has to be solved by a numerical approach. The result obtained is the bubble volume at any time and place averaged from the size distribution of the bubbles. This permits calculation of the local size distribution of the bubbles with the aid of the approximate analytical solution. In the second part of this contribution [2], this balance equation is extended to cover large gas volumes. Large bubbles and gas plugs then occur. These possess a very small interfacial area relative to their volume. They have high rise velocities and thus short residence times in the flow. They therefore participate to only a slight extent in mass and energy transfer and have to be considered, for example, in calculation of the conversion on a chemical reaction or the mode of action of an evaporator. The calculations are performed for pure liquids and compared with the authors' own and other experimental results. The liquids used industrially are generally mixtures of substances. In such liquids the coalescence behavior deviates significantly from that in pure liquids. The influence on coalescence and thus on the interfacial area is examined in the present paper.     

Verfahren zur Konditionierung von Rohgasen — Teil 3: Konditionierung durch Dosierung von Feststoffen,Flüssigkeiten oder Gasen

The operating performance of plant for removal of particulates from gases can be positively influenced by crude gas conditioning and other additive measures. These processes involve introduction of additional material or additional energy into the plant. Set goals are the reduction of particle emissions, reduction of operating costs, adaptation to new boundary conditions, or the opening up of new applications for the separators concerned. In the third of three surveys, conditioning by dosage of solids, liquids, or gases is considered. Precoating, heterogeneous condensation, particle formation by gas phase reaction, and other fundamental aspects are of relevance in this context. The possibilities and effects of additive dosage in the cases of wet separators, electrostatic separators, and filtering separators are presented, discussed, and — wherever possible — assessed with regard to practical relevance.