SLPTC modeling

Table 19.3 Operating regimes of the four homogeneous solubilization SLPTC models shown in Figure 19.5... 

In the SLPTC models previously developed, film mass transfer coefficients for the organic and aqueous phases are important parameters. In Chapter 14 we saw how the coefficient for gas-liquid systems can be determined. The same method can be used for liquid-liquid systems. In all of these cases, mass transfer rates are calculated using contactors with known interfacial areas. Where a solid phase is involved, the constant area criterion can be met by using a rotating disk of solid reactant or catalyst, as the case may be (Melville and Goddard, 1985, 1988 Hammerschmidt and Richarz, 1991). 

Generally, many experimental results can be described by applying pseudo-first-order or pseudo-second-order kinetics successfully. Sometimes, however, using confined kinetic data to elucidate exactly the reaction mechanism is indeed difficult. Hence, several simplified reaction mechanisms are usually employed to describe the kinetic behaviors of the reaction systems successfully. The technique of topochemistry is an effective method for achieving an approximate and quite precise interpretation of the kinetic data. Sirovski et al. [209] discussed the applicability of the models developed for the topochemical reactions in SLPTC. They considered that the simplest kinetic equation, called the Erofeev equation [210,211] ... 

In dealing with SLPTC, two types of mechanisms must be recognized, homogeneous and heterogeneous solubilization. We present the outlines of a reasonably rigorous model for each. 

Figure 19.7 A comprehensive model for SLPTC with provision for including any existing model for fluid-solid reactions (such as the sharp interface, volume reaction, or zone model) (Naik and Doraiswamy, 1997)...

A typical process model requires the estimation of several physicochemical properties of the reagents as well as transport and kinetic parameters. It is better if these are independently obtained and not obtained by parameter regression, where raw experimental data is force fitted to a model. Of the different systems listed in Table 16.1, we shall consider below the two most general and important systems, LLPTC and SLPTC. 

---