CVEN 6414 Aquatic Surfaces and Particles
Problem Set 4: Adsorption Competition
Using Visual MINTEQ, complete the following
assignment.
- Calculate the competitive adsorption of
copper and lead on hydrous ferric oxide (HFO) as a function of pH from pH 2
to 12 using the two-pKa double-layer model. For HFO, the concentration is 90 mg L-1, the surface area is
600 m2
g-1, the site density is 3 sites nm-2, and the pKaint values are 7.29 and 8.93.
The ionic strength is controlled using 0.1 M NaNO3. The
copper and lead surface complexation constants are listed in Table 6 of
Koretsky et al. (2000).
(a) For total copper and lead concentrations of 10-6 M.
(b) For total copper of 10-6 M and total lead of 10-7
M.
(c) For total copper of 10-6 M and total lead of 10-8
M.
Describe the effect of the competition on copper and lead adsorption as
illustrated by the three cases.
- Calculate the competitive adsorption of
phosphate and arsenate on hydrous ferric oxide (HFO) as a function of pH
from pH 2 to 12 using the two-pKa double-layer model. For HFO, the concentration is 90 mg L-1, the surface area is
600 m2
g-1, the site density is 3 sites nm-2, and the pKaint values are 7.29 and 8.93.
The ionic strength is controlled using 0.1 M NaNO3. The
phosphate and arsenate surface complexation constants are listed in Table 6
of Koretsky et al. (2000). Notice
that multiple surface species exist for both phosphate and arsenate.
(a) For total phosphate and arsenate concentrations of 10-5 M.
(b) For total phosphate of 10-5 M and total arsenate of 10-6
M.
(c) For total phosphate of 10-5 M and total arsenate of 10-7
M.
Describe the effect of the competition on phosphate and arsenate adsorption
as illustrated by the three cases.
Last updated on
May 20, 2007 by Joe
Ryan