Environmental Engineering Reference
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3.35 2 A mixture of polystyrene (2) in toluene (1) is said to follow the
Flory-Huggins model for activity coefficients. Given that ν 2 =
1000 ν 1 and χ = 0.6, obtain γ 1 and γ 2 as a function of x 2 at 298 K.
3.36 2 A mixture of methyl acetate (1) and methanol (2) has a Margules constant
A = 1.06 RT . Obtain a plot of the activity coefficient of methanol as a
function of its mole fraction at 298 K. Use the one constant Margules
equation.
3.37 2 If seawater at 293 K has the following composition, what is the total ionic
strength of seawater?
Electrolyte
Molality
NaCl
0.46
MgSO 4
0.019
MgCl 2
0.034
CaSO 4
0.009
3.38 3 One gram of a soil (total surface area 10 m 2 /g) from a hazardous waste
site in North Baton Rouge, Louisiana, was determined to contain 1.5 mg
of chloroform (molecular surface area 24 Δ
2 ) at 298 K. The soil sample
was placed in a closed vessel and the partial pressure of chloroform was
measured to be 10 kPa at 298 K. The heat of adsorption of chloroform
on the soil from the vapor phase was estimated to be 5 kJ/mol. If the
Langmuir adsorption isotherm is assumed, what is the adsorption constant
at 298 K?
3.39 3 The following data were reported by Roy et al. (1991) for the adsorption
of herbicide (2,4-dichlorophenoxy acetic acid designated 2,4D) on a typ-
ical Louisiana soil. Five grams of soil were equilibrated with 200 mL of
aqueous solution containing known concentrations of 2,4D and kept vig-
orously shaken for 48 h. The final equilibrium concentrations of 2,4D in
water were measured using a liquid chromatograph.
Final Equilibrium Aqueous
Initial Spike Aqueous
Concentration (mg/L)
Concentration (mg/L)
1.0
1.1
2.9
3.1
6.1
6.2
14.8
15.0
45.3
48.9
101.9
105.3
148.0
152.8
239.5
255.0
Based on appropriate statistics, suggest which of the three isotherms
(linear, Langmuir, or Freundlich) best represents the data.
3.40 2 The following adsorption data were reported by Thoma (1994) for the
adsorption of a polyaromatic hydrocarbon (pyrene) on a local sediment
(University lake, Baton Rouge, Louisiana).
 
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