Bestimmung der Ausblutechtheit fluoreszierender Papiere mit Hilfe eines licht-elektrischen Remissionsphotometers

Determination of the Bleeding Fastness of Fluorescent Papers with a Photoelectric Reflectance Photometer The visual comparison method for the determination of the bleeding fastness of optically brightened papers is replaced by a photoelectric method, using a reflectance meter. Values for the migration of less than 0.001% ( = 10ppm) of the brightening agent, based on the weight of the dry test paper, can be obtained from calibration curves of the respective fluorescer. In order to be able to choose optimum measuring conditions, the dependence of the difference in directional reflectance Δ R (%) on the effective wavelength filter F (λ_SW) has to be examined for each fluorescer. When immersing 50 calibration papers into the same calibration solution, the concentration of fluorescer contained therein does not decrease; all calibration papers have the same reflectance value. The value for the reflectance R is altered by impurities and permanent influence of light sources.     

Niederdruckumkehrosmose mit modifizierten polyacrylnitril-ultrafiltrationsmembranen

The chemical modification of polyacrylonitrile ultrafiltration (PAN-UF) membranes by hydroxylamine yields low-pressure reverse-osmosis (LP-RO) membranes containing amidoxime and hydroxamic acid groups besides nitrile groups. These membranes are positively charged at pH values of 4.0 to 6.5. The water permeability of the membranes decreases from 400 L h^?1 m^?2 to 15 L h^?1 m^?2 (p = 0.3 MPa) by this modification. A comprehensive characterization was carried out by retention curves, IR and NMR spectra, Hg porosimetry, measurement of membrane potentials and separation performance regarding different metal salts. Due to the Donnan exclusion these membranes have a retention of 88% at a filtrate flux of 8 L h^?1 m^?2(p = 0.3 MPa) regarding bivalent metal ions like Ca²⁺ and Mg²⁺ which cause the water hardness. Regarding heavy metal ions like Cu²⁺ and In³⁺ much higher filtrate fluxes from 90 to 100 L h^?1 m^?2 (p = 0.3 MPa) are possible. In water medium without any heavy metal ions the amidoxime and hydroxamic acid groups are hydrolysed to carboxylic acid groups which are able to reject multivalentanions. By this the water softening ability remains.     

Einsatz eines Online-Methanol-Messsystems zur Regelung von Zulaufsatzkultur-Fermentationen

For the optimization of fed-batch fermentations of methylotrophic organisms an online measuring method is presented, with which the methanol concentration in the medium during a fermentation can be determined by a purge gas pervaporation principle. In contrast to other analytical methods, this measuring method offers the possibility of maintaining the substrate concentration at a controlled value in processes with methanol as the central substrate. Difficulties, but also their overcoming in the adaptation of the measuring method to fermentation processes are described.     

H2O2 / O3, H2O2 / UV And H2O2 / Fe2+ Processes For The Oxidation Of Hazardous Wastes

Activated hydrogen peroxide produces very reactive OH-radicals which destroy hazardous contaminants in water. The principles and different methods of activation are described. Results from laboratory studies show the numerous applications of this new technology. A successful scaleup of laboratory tests to an industrial level is discussed. Finally, a cost estimate for treating different types of water with hydrogen peroxide is presented.     

Gas-chromatographische Trennungen mit modifizierten,linearen Temperaturprogrammen

Gas-chromatographic Separations with Modified Linear Temperature-programming The modified, linear temperature-programming is excellently suitable for the separation of a mixture of substances with widely differing boiling points because it is adaptable to every separation problem. After some basic considerations about TGC, the schedule of one such matrix-temperature-programm is described in this article with the help of an example of a mixture of fish oil fatty acid esters. The review-chromatogramm obtained by linear temperature-programming is divided into band groups, each of which shows optimum separation temperature (isotherm) and ultimately the isotherms are joined together with linear heating.