The true density of the solid material in an activated alumina particle is 3.675 g/cm3. The density of the particle determined by mercury displacement is 1.547 g/cm3. The surface area (Sg) by adsorption measurement is 175 m²/g. The bulk density of bed (which is defined as mass of catalyst particle per volume of reactor bed) is 0.81 g/cm³. From this information, Determine, a) the pore (void) volume per gram, b) the porosity of the particles, c) the mean pore radius (ā), d) what fraction of the total volume of the bed is void space between the particles, e) what fraction of the total volume of the bed is void within the particles

Catalyst particles are entrapped in the center of a porous membrane material. The purpose of this is to protect the catalyst so that it can be recovered and reused. This structure shown below is immersed in an aqueous solution containing a proprietary reactant called component A. Component A can only diffuse through the top and bottom faces of this structure. The dimensions of the top face and the bottom face are same (10cm x 10cm). The thickness of the top membrane is 0.1cm and the thickness of the bottom membrane is also 0.1cm. Furthermore component A is instantaneously consumed by the catalyst at a constant rate of 144 mg/hour when it enters the compartment where the catalyst is located.   If the effective diffusivity of component A in this application is 2 x 10-5 cm2/s in the membrane calculate the concentration of component A in the surrounding solution that is needed to maintain the consumption rate. (You may assume the surrounding solution is well mixed and thus void of any…

1) A biofilm is a layer-like aggregation of microscopic animals, plant or bacteria attached to a solid surface. Assume such a biofilm where the reactant is consumed Bulk fluid only at the solid surface, maintaining a particular value of surface concentration. Calculate the steady-state reactant flux into a biofilm of thickness 0.01 cm, if the diffusivity of the reactant in the biofilm is 0.8 cm²/day. Assume the reactant concentration in the bulk fluid to be uniform at 3.2 mg/liter. At the surface, reactant concentration is 0.25 mg/liter. Biofilm Surface

Consider a diffusion process in a semi-infinite solid with a source at x=0 mm, the concentration of the diffusing species is 2 nm-3 at x=5 mm and t=1 hr (since the start of the process). At what time the concentration at x=15 mm will reach 3 nm-3 ?

in a 2-hour carburizing treatment, what temperature is required to obtain a 0.5% concentration of carbon at a depth of 0.5 mm below the surface of steel with a carbon concentration of 0.2%?considers that the inert gas used is enriched with carbon atoms at a concentration of 1.10% and that iron has an fcc structure

A new type of porous material serves as food packaging film, as shown in the figure below. The film rests on a nonporous metal plate. The packaging film is 0.20 cm thick (2.0 mm). The food contains liquid water, which exerts a vapor pressure of 0.030 atm at 25°C. At 25°C, the effective diffusion coefficient of water vapor in the porous film is 1.3 x 10^-4 cm/s, and the molecular diffusion coefficient of water vapor in air is 0.26 cm/s. You may assume that the total system pressure is constant at 1.0 atm, and initially, the gas space of the porous film contains air and no water vapor. How long will it take for the water vapor to achieve a partial pressure of 0.0150 atm at the back surface of the film (z = 0) at 25°C?

A wet sphere of gelatin gel at a temperature of 20 "C contains a uniform concentration of urea of 0.05 kg mol/m'. The sphere has a diameter of 16 mm. The sphere is suddenly immersed in turbulent water which initially contains urea of concentration 0.1 kg mol/m'. The diffusion coefficient of the urea in the gelatin gel is 8.59 * 10*" m/s. The convective mass transfer coefficient ke is 1.07375 x 10 m/s and the equilibrium distribution coefficient K is 1. For radial mass transfer only, listing your assumptions, calculate, (a) the concentration at a distance of 4,8 mm from the midpoint of the sphere after 25.87 hours of mass transfer. (b) the time by which the concentration, c, at the centre of the sphere is 0.09975 kg mol/m3

Find the diffusion coefficient of ammonia-hydrogen system at 25 °C and atmospheric pressure and correct its value for 85 °C and compare it with experimental values.

A quiescent body of water has a depth of 600 mm. The DO level at the bottom after 16 days is 3.5 mg/l when the surface is exposed to the atmosphere at a temperature of 25o Determine the DO of the water body. The saturated DO at 25oC is 8.5 mg/l and the diffusion coefficient (kd) at 25oC is 2.5 x 10-3 mm2/s.

1. If the temperature decreases will the rate of diffusion will decrease or increase? 2. If the surface area for diffusion increases will the rate of diffusion increase or de- crease? 3. If equal amounts of Ar and He are being placed in a porous container and are al- lowed to escape, which substance will escape faster?