Photoinitiated oxidation of geosmin and 2-methylisoborneol by irradiation with 254 nm and 185 nm UV light

The degradation of geosmin and 2-methylisoborneol (2-MIB) by UV irradiation at different wavelengths was investigated under varying boundary conditions. The results showed that conventional UV radiation (254 nm) is ineffective in removing these compounds from water. In contrast to the usual UV radiation UV/VUV radiation (254 + 185 nm) was more effective in the removal of the taste and odour compounds. The degradation could be described by a simple pseudo first-order rate law with rate constants of about 1.2 × 10⁻³ m² J⁻¹ for geosmin and 2-MIB in ultrapure water. In natural water used for drinking water abstraction the rate constants decreased to 2.7 × 10⁻⁴ m² J⁻¹ for geosmin and 2.5 × 10⁻⁴ m² J⁻¹ for 2-MIB due to the presence of NOM. Additionally, the formation of the by-product nitrite was studied. In the UV/VUV irradiation process up to 0.6 mg L⁻¹ nitrite was formed during the complete photoinitiated oxidation of the odour compounds. However, the addition of low ozone doses could prevent the formation of nitrite in the UV/VUV irradiation experiments.     

Ermittlung des Aufbaus und der Stoffkennwerte von Außenbauteilen mit Hilfe von In‐situ‐Messungen und FEM‐Berechnungen

Determination of the construction and the material identity values of outside building components with the help of in‐situ measuring procedures and FEM‐simulation calculations. The aims formulated nationwide and internationally to the climate protection can be achieved by combining of the energy‐efficient construction and rehabilitation of the existing buildings. Knowledge about the construction and the material identity values of the warmth‐transferring outside components is a condition for the energetic balance of buildings. The essential information to this can frequently be no more taken from the construction documents particularly for older buildings since they are no longer traceable or incomplete. At the example by univalve and bivalve out‐wall construction it is shown that the thermophysical qualities can be determined with the help of in‐situ measuring procedures and FE‐simulation calculations without destruction.     

Comparative Hydrodynamic Analysis of Narrow and Pilot‐Scale Bubble Columns with Internals

For a stable operation of exothermic processes in bubble column reactors, an appropriate heat control is required, e.g., through dense internal tube bundle heat exchangers. Their impact on hydrodynamic characteristics and scaling approaches is studied for columns of different scales. Two different column dimensions (DN100 and DN400) were equipped with two common tube patterns of triangular and square pitches to study local fluid dynamics. Based on geometrical tube bundle scaling quantities, hydrodynamic similarity as a scale‐up criterion with respect to average holdups, phase distributions, and local gas structures can be reached.     

Hardness and Fracture Toughness of Solid Solutions of Mg2Si and Mg2Sn

Semiconductors - Thermoelectric material development typically aims at maximizing produced electrical power and efficiency of energy conversion, even though sometimes, this means adding expensive...     

Morphology of Flashing Feeds at Critical Fluid Properties in Larger Pipes

Tailored conditioning and control of flashing feeds in industrial applications requires knowledge of the evolving flow morphology and phase fractions along the feed pipe. Design methods obtained from reference systems (e.g. water-air) are hardly applicable for commercial scales and critical fluid properties (e.g. high vapor densities, low surface tension). In this study, the flow morphology of flashing feeds in a novel refrigerant test rig at critical fluid properties was analyzed using wire-mesh sensors at two locations along the feed pipe and experimental data from the water-air system.     

Sintering ZrO2/TiC Composites with TiH2: The Role of Transient Liquid Phase and of Substoichiometry

Sintering tetragonal ZrO₂ with 35 vol% TiC results in a microstructure where all grain facets are free of amorphous interfaces independent of sintering aids as TiH₂ or MgO/ Y₂O₃; grain sizes are below 1 μm. With substoichiometric TiC_1-x, a relative density of 95% and closed porosity are obtained at a lower sintering temperature than with stoichiometric TiC, but subsequent cladless hot isostatic pressing (HIP) is required to achieve 99% density. High densities of 98% accompanied by good mechanical properties become possible by pressureless sintering with the use of TiH₂. MgO/Y₂O₃ doping also promotes densification, but results in less transformable zirconia and increases the number and size of amorphous triple junctions. The consequences are a lower fracture toughness and strength.     

Strategie für eine Konversion der Chlorchemie

Strategy for Conversion of Chlorine Chemistry . After years of discussion about ?cessation of chlorine chemistry”?, the study entitled ?Conversion of Chlorine Chemistry”? [1] commissioned by the Environmental Ministry of the State of Hesse in Germany and undertaken by Prognos AG provides the very first detailed comparative ecological and economical assessment of production process and products of ?chlorine chemistry”? and industrially feasible alternatives and presents a strategy for partial transformation. This accomplished on the basis of a systematic assessment of risks and benefits, as demanded by the Geman parliametary commission ?Protection of Humankind and the Environment”?.     

Structural engineering of nanoporous anodic aluminium oxide by pulse anodization of aluminium

Nanoporous anodic aluminium oxide has traditionally been made in one of two ways: mild anodization or hard anodization. The first method produces self-ordered pore structures, but it is slow and only works for a narrow range of processing conditions; the second method, which is widely used in the aluminium industry, is faster, but it produces films with disordered pore structures. Here we report a novel approach termed "pulse anodization" that combines the advantages of the mild and hard anodization processes. By designing the pulse sequences it is possible to control both the composition and pore structure of the anodic aluminium oxide films while maintaining high throughput. We use pulse anodization to delaminate a single as-prepared anodic film into a stack of well-defined nanoporous alumina membrane sheets, and also to fabricate novel three-dimensional nanostructures.