Page 262 - Adsorbents fundamentals and applications

CARBON NANOTUBES 247

150 CO /Basal plane
Total energy change (kcal/mol) −30 2 SO /Basal plane
2
90
CO /Edge plane
30

−90
2
2
−150
−210 SO /Edge plane
0 1 2 3 4 5 6
Distance (Å)
Figure 9.10. Potential energy as a function of internuclear distance from semi-empirical (INDO)
molecular orbital theory calculation (see Chapter 8) (Chen and Yang, 1993, with permission).
The absolute values from INDO are too high, but the relative values for different systems are
correct. The edge plane is the zigzag edge.

100
Adsorption in No + O 2 Desorption in He
Adsorption/desorption amount (mg/g-sorbent) 60 in SO + O 2
80

40

2
20

in CO + O 2
2
0
0 30 60 90 120 150 180
Time (min)
Figure 9.11. Adsorption/desorption of NO x ,SO 2 ,and CO 2 on MWNTs at 25 C. Conditions for
◦
adsorption: 1000 ppm NO, 500 ppm SO 2 , or 10% CO 2 , each with 5% O 2 and balance He at
1 atm. (Long and Yang, 2001b).