Suspension models particle shape effect

The solvent-mediated transformation of o -L-glutamic acid to the S-form was quantitatively monitored over time at a series of temperatures [248]. The calibration model was built using dry physical mixtures of the forms, but still successfully predicted composition in suspension samples. Cornel et al. monitored the solute concentration and the solvent-mediated solid-state transformation of L-glutamic acid simultaneously [249]. However, the authors note that multivariate analysis was required to achieve this. Additionally, they caution that it was necessary to experimentally evaluate the effect of solid composition, suspension density, solute concentration, particle size and distribution, particle shape, and temperature on the Raman spectra during calibration in order to have confidence in the quantitative results. This can be a substantial experi-... 

The traditional study of suspension crystallization has been carried out using the MSMPR crystallization model. It has been found that uniform mixing in a commercial-size crystallizer, as required by the MSMPR model, is impossible to achieve. Therefore, the understanding of industrial crystallization is hampered by the use of the MSMPR model. Also, it is difficult to experimentally study the effects of mixing on crystallization, as described earlier in Section 64.2.5. Therefore, the CFD presents the means for local simulation in the tank. Furthermore, CFD simulation enables the tank to be designed so that the shape and the positioning of the impellers and the liquid velocity create the optimal level of supersaturation and mass transferrate in all locations. This is likely to result in a narrowing of the particle size distribution. 

The results reported on the viscosity of suspensions may be summarized somewhat as follows Attempts have been made, both theoretically and experimentally, to establish criteria based on hydrodynamics for judging behavior in solutions of high polymers. Theoretically, a series of equations has been obtained for spheres and for rod-shaped particles, which lay claim to validity according to the conditions obtaining. Experimentally, these equations have been examined by using model substances, the size and shape of which could be accurately ascertained under the microscope. As far as can be seen, the theoretical relations can be essentially confirmed. Moreover, independently of theory, the models have widened our outlook on important matters such as particle orientation, behavior of flexible fibers, effect of concentration, etc. 

The physical significance of the zeta potential is discussed in the following section. The suspension could be characterised by particle charge density, which can in principle be determined from the electrophoretic mobility, but which requires certain assumptions regarding the particle size and shape distribution and conductivity effects. The zeta potential is the most commonly used parameter for characterising a suspension, and can be determined from measurements of particle velocity or mobility in an applied field using commercially available electrophoresis cells. In practice electrophoretic mobilities are not easy to measure accurately, and since the Smoluchowski equation is based on a model of doubtful validity, the view sometimes expressed that "zeta potentials are difficult to measure and impossible to interpret" has a ring of truth but is probably unduly pessimistic. The Smoluchowski relation is valid provided that the double... 

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