Hi Aiman,

depending on the packing it could be both inter and intra particle porosity. in soil inter particle porosity is in the range of few nano meter and intra particle in the range of micrometer.

I do not get your point , depending upon packing, can you please explain it further?

Both of them.

The Inter-particle porosity are the large pores between particles while the Intra-particle porosity are the smaller pores within the particle. For clarity consider the Inter-particle as the buses that run between towns and the Intra-particle as the metro line within the town. As to which is important, for flow through an adsorption bed then the large pores are important. As these become smaller due to a reduction in the particle size or a greater packing then there will be greater restrictions to flow. However, for the adsorption on the surface then the narrow pores within the particles will increase the available surface area. An ideal system needs both types of porosity with good connectivity between them.

Best regards,

Malcolm

In the case of a single porous particle, we use the term "internal diffusion (internal mass /transfer/transport)" or "intraparticle diffusion (mass transfer / transport)" to describe the mass transport phenomena in the porous structure. In the case of a single porous particle or not, we use the term external diffusion of interparticle diffusion to describe the mass transfer phenomena form bulk to particle surface. In the case of the bed we are not talking about "iner or intra phenomena", but we can talk about axial dispersion, but it is a completely different phenomenon of macroscopic than molecular nature. And one more thing - depending on the size of the pores in the particle we can deal with either molecular diffusion or Knudsen diffusion. Instead of "interparticle porisity" it is better to use bed porosity. The same in case of single particle. "Particle porosity" is the correct term.

Regards,