$($a$)$

$($i$)$ Two glass bulbs are joined together by a length of capillary tube.

Oxygen diffuses from one bulb to the other which is filled with

carbon dioxide. Given that the partial pressure of oxygen in one

bulb is $5{10}^{3}Pa$ and in the other is $4\mathrm{.}9{10}^{3}Pa,$ using Fick's law

calculate the length of the capillary tube connecting the two bulbs.

DATA

Diffusion coefficient of oxygen, $D$

$3\mathrm{.}44{10}^{-5}{m}^2{s}^{-1}$

Gas Constant, $R$

$8\mathrm{.}31m^{3}Pamo{l}^{-1}{K}^{-1}$

Temperature, $T$

$298K$

Flux, J

$8{10}^{-6}mol{m}^{-2}{s}^{-1}$

$($ii$)$ State $3$ major assumptions used in solving this problem.

$($b$)$ Wastewater is processed in an adsorption column packed with activated

carbon. Equilibrium data for the process in provided in Table $1.$

$($i$)$ State the equations of the three most common isotherms, Linear,

Langmuir and Freundlich, defining any symbols you use.

$10\%$

$($ii$)$ By manipulating and plotting the data in Table $1,$ determine which of

the isotherms best fits the equilibrium data.

Table $1$

$($c$)$ An air stream containing $9$ mole $\%$ carbon dioxide is to be processed down

to $5$mole$\%$ using water in an absorption column. The water initially

contains no carbon dioxide and has an equilibrium line of $y^{**}=1\mathrm{.}073x$

$($where $y^{**}$ is the equilibrium mole fraction of the gas and $x$ is the actual

mole fraction of the liquid$).$ You plan to use a liquid flow that is twice the

minimum flowrate to achieve this.

$($i$)$ Calculate the mole $\%$ of carbon dioxide leaving in the water stream.

$15\%$

$($ii$)$ It is assumed the overall gas side mass transfer coefficient controls

this system. Using the information below calculate the overall gas

side mass transfer coefficient, $K_{g}a.$

DATA

Gas side mass transfer coefficient, $k_{g}a,0\mathrm{.}092kmol{s}^{-1}$ bar ${?}^{-1}{m}^{-2}$

Liquid side mass transfer coefficient, kla,$0\mathrm{.}003s^{-1}$

Henry's law constant, $m$

$1\mathrm{.}073$ bar m ${?}^{2}kmo{l}^{-1}$