• data collected by Sajadi (MS thesis, CSULB) as well as data from the literature • parts of mathematical models developed and published in the literature; and the “internal pores” mathematical model developed by Jorgensen (MS mini-thesis, CSULB).

The composite model can be used to compute the time required to remove the hydrocarbons would be the sum of the times required for the removal for:

1. Hydrocarbons caught up between the particles. The computation for this part of the removal process is known to be dependent upon: volumetric flow rate of air; the temperature of the system and the properties of the bed (average particle size; porosity) 2. The hydrocarbons caught up within the pores of the particles which are open to the outside: Jorgensen's simple model assuming cylindrical pores and with diffusion as