CE 420/520 Environmental Engineering Chemistry
Problem # 6
Due date: Dec. 10, 2004
Solve the following problems in your book
1.
Problem 1 page 426
2.
Problem 6, page 428
3.
Problem 9, page 428
4.
Problem 17, page 430
5.
An adsorption study on X by activated carbon was conducted by adding a known amount of
activated carbon to six flasks which contain 200 mL of an industrial waste. An additional flask
containing 200 mL of waste but no carbon is run as blank. Determine the Langmuir isotherm for
the activated carbon.
Flask
1
2
3
4
5
6
7
Wt of carbon
804
668
512
393
313
238
0
Final Concentration of X (mg/L) in Industrial Waste
4.7
7.0
9.31
16.6
32.5
62.8
250
For CE 520 Students
6.
Construct a p-pH diagram for soluble N species (NO3-, NO2-, NH4+ and NH3). Given the
following equations (if you need more equations look in Table 7-1, page 329).
NO3- + 10H+ + 8e- < == > NH4+ + 3H2O
NO3- + 2H+ + 2e- < == > NO2- + H2O
NO2- + 8H+ + 6e- < == > NH4+ + 2H2O
NH4+ < == > NH3 + H+
E0 = 0.88
E0 = 0.84
E0 = 0.89
pKa = 9.3
Label A and B where you will find the following conditions on your diagram:
(A) Flowing water in a stream
(B) At the bottom of the sediment of a river
7.
Two separate experiments were conducted by equilibrating 1.0 and 2.0 gm of clay in 100 mL of
methylene blue solution. The initial concentration of methylene blue was 10 -4 M. The final
concentrations after equilibration were 0.6 x 10-4 M and 0.4 x 10-4 M for the 1.0 and 2.0 g of clay
respectively. Assuming that Langmuir equation is obeyed (monolayer coverage), estimate the
specific surface area (m2/gm) of the clay by assuming the cross-sectional area of methylene blue
molecule to be 65 angstrom2.