Effects of Electric Field on Nonlinear Chemical Systems: On the Way to Electrolyte Microchips

Abstract

Problems of theoretical description and practical use of nonlinear phenomena arising in the conduction of electric current in electrolytes with a non-homogeneous spatial distribution of species concentrations and with equilibrium reactions are studied in this contribution. Mathematical model based on the mass balances of components, Nernst-Planck equation and Poisson equation is presented. Results of numerical simulations are discussed for systems: (i) acid-base electrolyte diode in the hydrogel and (ii) bipolar ion-exchange membranes. 236 A New Static Mixer for Turbulent Flow M a r k u s F l e i s c h l i P e t e r M a t h y s T h o m a s G r u È t t e rA new static mixer for turbulent flow has been developed. The integrated feeding device is designed for mixing ratios of additive to main stream of 0.05 ± 30 %. The mixer has a very short installation length (`0.5 pipe diameter). It can be easily mounted between two flanges. Mixing length and pressure drop are reduced compared to the traditional SMI mixer. 237 Scale-Up of Processes Using Material Systems with Variable Physical Properties M a r k o Z l o k a r n i k A ± 8010 Graz, Grillparzerstrasse 58Two processes are similar to one another if they take place in a similar geometrical space and if all the dimensionless numbers which describe the process have the same numerical value: A complete similarity requires a geometrical, material and process-related similarity. When measurements are to be performed in a ªcold mod-elº, but the industrial plant operates at high temperatures (petrochemicals; T 800 ± 1000 C), different temperature dependence of physical properties can cause problems. When measurements are to be performed with model fluids to gain information about scaling-up of an apparatus for the treatment of cell cultures in biotechnology (mammal and plant cells, yeasts), their rheological behaviour (pseudoplactic and viscoelastic) can present problem. Which model system may we choose? The answer will be unambiguous: We may choose any model material system whose dimensionless material function in question is similar to that of the original material system. It will be shown how to proceed to arrive at it.Homogeneous and heterogeneously catalyzed esterification kinetics of lactic acid with methanol are studied in this work. The effect of temperature, catalysts loading and initial reactant ratio on reaction kinetics is evaluated.Experimental reaction rates were correlated by some models based on homogeneous and heterogeneous (dual and single site mechanism) approaches. Non-ideality of the liquid phase was taken into account by using activities instead of mol fractions. Prediction of the activity coefficients were made by UNIFAC. Parameters of the different models were obtained by the simplex search method. Figure.Variation of conversion with time for the non-catalyzed esterification of lactic acid with methanol at different temperatures. The reaction was carried out with an initial methanol/lactic acid ratio R M/LH =3. The continuous line represents the model ...