Biomedical Engineering Reference
In-Depth Information
This review attempts to analyze and discuss some of the literature that has been
published to date on the ability of chitosan, modified chitosan, and chitosan deriva-
tives to adsorb heavy metal ions from solution and some kinetic models studied.
ChemiCally modiFied ChitosaN
metal ion uptake of Chitosan-crown ethers derivatives
Two kinds of novel chitosan-crown ether resins, Schiff base type chitosan-benzo-
15-crown-5 (CTS-B15) and chitosan-benzo-18-crown-6 (CTS-B18), were synthesized
through the reaction between-NH
2
in chitosan and -CHO in 4'-formyl benzo-crown
ethers as shown in Figure 3. The structures of these derivatives were characterized
and the elemental analysis results show that the mass fractions of nitrogen in CTS-
B15 and CTS-B18 are much lower than those of chitosan. The adsorption properties
of CTS-B15 and CTS-B18 for Pd
2+
, Cu
2+
and Hg
2+
were studied and the experimental
results revealed that these adsorbents have good adsorption characteristics and high
particular adsorption selectivity for Pd
2+
when Cu
2+
and Hg
2+
are in coexistence. These
novel chitosan-crown ether resins of CTS-B15 and CTS-B18 will have wide-range
of applications for the separation and concentration of heavy or precious metal ions
(Chang-hong et al., 2003).
Figure 3.
Structure of (CTS-B15) and (CTS-B18), (Chang-hong et al., 2003).
Varma et al. (2004) discussed the metal complexation of different chitosan crown
ethers derivatives in detail (Varma et al., 2004). Newly prepared Schiff base-type
chitosan-azacrown ethers were prepared by a reaction of chitosan (CTS) with
N
-(4'-
formylphenyl) aza-crown ethers, and were then converted to secondary-amino deriva-
tives by the reduction of CTS-azacrown ethers with sodium borohydride (Malkondu et al.,
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