Problem#$35$: Desorption practice problem:

This problem is based on a study conducted by Okoniewski where air has been used to strip volatile organic compounds. At $70F$ and $15a,14,000$lbmo$\frac{l}{h}$ of water were stripped with $150$lbmo$\frac{l}{h}$ of air. A $20$ plate tower is used with a plate efficiency of only $20\%$ has been used. The waste water contains three pollutants in the amounts shown below. Included are the properties from the $1996$ Technical Data Book $-$ Petroleum Refining of the American Petroleum Institute. For all the compounds, the organic concentrations are less than the solubility values, so only one liquid phase exists.

$\backslash$table$[[$Organic Compound,$\backslash$table$[[$Concentration in$],[$waste water $($mg$/$L$)]],\backslash$table$[[$Solubility in water at $70],[\backslash$deg F$,$ mole fraction $($x$\_($i$)^($s$))]],\backslash$table$[[$Vapor pressure at $70],[\backslash$deg F$,\backslash$psi a$($P$\_($i$)^($s$))]]],[$Benzene$,150,0\mathrm{.}00040,1\mathrm{.}53],[$Toluene$,50,0\mathrm{.}00012,0\mathrm{.}449],[$Ethyl Benzene,$20,0\mathrm{.}000035,0\mathrm{.}149]]$

Note that when solubility data is available and the $K$ value for each component can be obtained using the equation: $K_i=\frac{P_i^S}{x_i^{S}P}.$

It is required that $99\mathrm{.}9\%$ of the total VOCs must be stripped$/$desorbed$.$

$($a$)$ Which of the three components is easiest to desorb. Why?

$($b$)$ Calculate the percentage of desorption achieved under the given conditions.

$($c$)$ Has the desired degree of desorption achieved? If not can you provide a quick suggestion to achieve the desired target? Justify with your calculations.