Biomedical Engineering Reference
In-Depth Information
while Zn
2+
was moderately positive. All of the binary combinations were moderately
positive except for NiZn, which was moderately negative, and ZnCd, which was only
slightly positive. The tertiary combinations were as on the native biomaterial, all moderately
negative. Again, this only reflects relative inhibition of metal ion binding. The data listed in
Table 7a reveals single metal bound values were all about 25 mol g
-1
(average 24.5). These
are compared to those for the binary combinations which ranged from 30 - 32 mol g
-1
(average 31.0), an increase of 6. Similarly to the native material, the tertiary combinations
ranged from 29 - 39 mol g
-1
(average 31.1), a slight increase which may not be statistically
significant. This again suggested that some degree of cooperativity in binding with the
primary binding mechanism involving electrostatic attractions.
4. Conclusions
Carboxylate groups are important functionalities for metal ion adsorption for the
biomaterial
Datura innoxia
. Esterification of these functionalities was observed to reduce
metal binding capacity 30-40%. Three metals of similar binding affinity to the biomaterial
(Cd
2+
, Ni
2+
, and Zn
2+
) were exposed sequentially to both the native esterified biomaterials
immobilized within a polysilicate matrix. Removal of surface carboxylates significantly
impacted the binding of each metal ion and the impact of each metal bound on the binding
of the others. A model involving at least 16 binding sites for these metal ions revealed a
majority of binding to involve species-independent or common sites and the presence of
cooperativity for some metal-ion binding environments
5. Acknowledgements
The authors wish to acknowledge the financial support of the Waste-management
Education and Research Consortium funded by the US Department of Energy through New
Mexico State University.
6. References
Davis, T.A.; Volesky, B.; Mucci, (2003) A. A Review of the Biochemistry of Heavy Metal
Biosorption by Brown Algae.
Water Research
vol.37, No. 18 (November 2003) pp.
4311-4330 ISSN: 0043-1354.
Drake, L.R.;.Rayson, G. D. (1996) Plant Materials for Metal Selective Binding and
Preconcentration
Analytical Chemistry
, vol.
68
, no. 1 ( Jauary 1996), pp. 22A-27A.
ISSN 0003-2700
Drake, L.R.; Lin, S.; Rayson, G.D. (1996) Chemical Modification and Metal Binding Studies
of
Datura innoxia
.
Environmental Science and Technology
, vol.
30
, no. 1 (January 1996)
pp. 110-114. ISSN 0013 936X
Drake, L.R.; Hensman, C.E.; Lin, S.; Rayson, G.D.; Jackson, P.J. (1997) Characterization of
Metal Ion Binding Sites on
Datura innoxia
by Using Lanthanide Ion Probe
Spectroscopy.
Applied Spectroscopy,
vol.
51
, no. 10 (October 1997) pp. 1476-1483.
ISSN 0003-7028
