Farbmessung an transparenten Flüssigkeiten

Colour Measurements at Transparent Liquids In the chemical industry, the colours of transparent liquids are still determined by visual comparison of the products with the corresponding series of colour standards. This subjective colour assessment, which is susceptible to faults, was rendered more objective by means of the new DIN-standard set up in 1989 to determine the colour of the products by measuring. This DIN 53995 defines colour measurements at liquids in accordance with DIN 5033 for colour measurements at surfaces which has been in force since 1931. The liquid tester LTM1 by Dr. Lange was developed on the basis of these standards and enables objective colour assessment in compliance with DIN 53995 and iodine, Hazen and Gardner colour scales.     

Vermischungseffekte in Flüssig/Flüssig-Extraktionskolonnen

Axial mixing in liquid/liquid countercurrent extractors . Methods are considered for the determination of longitudinal mixing in many countercurrent extractors. It is found that only the single phase mixing of the continuous phase can be accurately determined; with certain reservations this also applies to the disperse phase. In the case of RDC and ARD in particular, correlations are available which permit calculation of Bodenstein numbers for both phases. Such scale-up calculations are not recommended for many extractors. It is very important to establish adequate correlations for calculation of mixing of the disperse phase in order to obtain exact dispersion heights in connection with those of the continuous phase.     

Vorausberechnung von Flüssig/Flüssig-Gleichgewichten

Calculation of liquid/liquid equilibrium . The knowledge of phase equilibrium is of great importance in the design of extraction processes. A few years ago, the engineer had to rely on empirical and semi-empirical methods, whilst today the calculation of multicomponent systems can be performed with models based on molecular thermodynamics. In this survey, sources of data, principles of calculation, and methods for the determination of multicomponent liquid/liquid equilibria are presented. Results and accuracy of recent methods are compared.