What is shrinking core method?
The shrinking core model is used to describe situations in which solid particles are being consumed either by dissolution or reaction and, as a result, the amount of the material being consumed is “shrinking.” This model applies to areas ranging from pharmacokinetics (e.g., dissolution of pills in the stomach) to the …
In which model reaction first occurs at outer skin of particle?
Progressive-Conversion Model (PCM). Here we visualize that reactant gas enters and reacts throughout the particle at all times, most likely at different rates at different locations within the particle. Here we visualize that reaction occurs first at the outer skin of the particle.
What is progressive conversion model?
Progressive-Conversion Model (PCM): In present model, we assume that reactant gas enters and reacts throughout the particle at all times, most likely at different rates at different locations within the particle.
What is the difference between progressive conversion model and shrinking core model?
In most cases, the shrinking-core model (SCM) approximates real particles more closely than does the progressive conversion model (PCM). Comparison of Models with Real Situations. reactant A through the film surrounding the particle to the surface of the solid.
What is the significance of Hatta number in fluid fluid reactions?
The Hatta number (Ha) was developed by Shirôji Hatta, who taught at Tohoku University. It is a dimensionless parameter that compares the rate of reaction in a liquid film to the rate of diffusion through the film.
What is progressive-conversion model?
What is Hatta number and enhancement factor give their usefulness?
How do you calculate enhancement?
The SERS enhancement factor (EF) is given by: EF= NvolIsurf/NsurfIvol where Nvol and Nsurf are the number of molecules probed in the aqueous sample and on the SERS substrates, respectively. Ivol and Isurf are the corresponding normal Raman and SERS intensities.
How do you solve the shrinking core problem?
Solution of the entire pseudo-steady state problem (commonly referred to as the shrinking core model) is achieved by analytical integration of eqn. (53) and substitution of the result into eqn. (55), subsequently eliminating the unknown Ca by the use of eqn. (54).
What is the shrinking core model and the shrinking particle model?
Two models developed in Chapter 9 to describe the kinetics of such reactions are the shrinking-core model (SCM) and the shrinking-particle model (SPM). The SCM applies to particles of constant size during reaction, and we use it for illustrative purposes in this chapter.
Is the shrinking core the best model of reacting gas-solid systems?
Despite these complications Wen (1968) and Ishida et al. (1971), on the basis of studies of numerous systems, conclude that the shrinking core model is the best simple representation for the majority of reacting gas-solid systems. [Pg.581] A batch of solids of uniform size is treated by gas in a uniform environment.
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