Chemical Catalytic or Physical Sink

When the microphase is an externally introduced catalyst, as in a slurry reactor or a physically adsorbing solid such as microfine carbon particles, the solute is consumed within (or on) this phase. Thus there is no accumulation of A in the microphase, resulting in steady-state operation. This enables the use of the simple film theory that is restricted to steady-state transport and is inherently inapplicable to time-dependent situations (see chapter 4). 

When a microphase is added to the system, the effect is to increase the specific reaction rate by increasing the overall mass transfer rate. This leads to different effects in different regimes. Regime 1 being kinetically controlled is little influenced by fluctuations in the transport rate, particularly when this rate increases, as in the present case. Regime 4 is rather distinctive and involves complete depletion of B in the film (and is considered separately). Thus we are largely concerned with slow and fast reaction regimes (2 and 3). 

Where liquid-liquid systems are concerned, it is conceivable that the microphase is present in both liquid phases. The analysis of such systems is more complicated and will not be attempted here (see Janakiraman and Sharma, 1985). The developments that follow are restricted to systems where the microphase is present only in the continuous phase. 

Stow Reaction Regime (No Reaction in Film Liquid) 

The condition for the slow reaction regime where no reaction occurs in the film and the rate equation for this case are given in Table 14.2. This rate increases in the presence of a microphase as a result of the uptake of A from phase 1. 

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