Environmental Engineering Reference
In-Depth Information
Figure 9. Polysaccharide concentration dependence of
R
ct
for 10 mM Fe(CN)
6
3-
in 2, 3, 4 wt% agarose
(diamonds) and 2, 3, 4 wt% κ-carrageenan (squares) and aqueous solution (crosses) containing 0.5 M
KCl at the rest potential [3].
Conclusive Remarks
These results are summarized as follows. Tight and elastic polysaccharide solids could be
formed. The cyclic voltammograms in the agarose and the κ-carrageenan solids show almost
similar features to those in liquid water including the redox potential and peak currents, but
with a slightly larger peak separation for the solid systems. Electrochemical impedance
spectra (EIS) were measured successfully in the polysaccharide solid. The
D
app
values of
Fe(CN)
6
3-
in the solids were almost the same as in an aqueous solution. The charge transfer
resistance (
R
ct
) of the electrode surface in the κ-carrageenan solid was even smaller than that
in an aqueous solution, although it was larger in the agarose solid than that inκ-carrageenan
solid. The
R
ct
tended to decrease with the polysaccharide concentration in the solid. The
double layer capacitance (
C
dl
) on the electrode surface in the Fe(CN)
6
3-
aqueous solution
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