Page 160 - Adsorbents fundamentals and applications

CHEMICAL MODIFICATION OF SILICAS AND MOLECULAR IMPRINTING 145

50

CO 2 Weight change (mg/g sorbent) 30
40

20

10 Adsorption (25°C)
Desorption (75°C)
Re-adsorption (25°C)

0
0 200 400 600 800
Time (min.)
Figure 6.9. Cyclic CO 2 adsorption/desorption on amine-grafted MCM-48.

14

12
Amount adsorbed (cm 3 /g) 8 6
10

4
MCM48-NH 2
2 SiO 2 -NH 2
0
0 0.0002 0.0004 0.0006 0.0008 0.001
P H 2 S (atm)
Figure 6.10. Adsorption isotherms of H 2 S on amine-modified silicas at room temperature.

organic functional groups and microporosities could be prepared (Katz and Davis,
2000). The synthesis for a silica with three amine groups in each cavity (of the
size of 0.8–1.0 nm) is shown in Figure 6.12. TEOS was used for polymerization
in the sol-gel process. The imprint molecules contained one, two (in the para
positions), and three (in the 1, 3, and 5 positions, as shown in the figure)