Environmental Engineering Reference
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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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