Biomedical Engineering Reference
In-Depth Information
WATER
SUBSTRATE
Closed Inaccessible Pore
Open Pore
ADDING
SOLUTION
Partially Accessible Bottle-necked Pore
CASE I
CASE II
CASE III
Accessible Pore Water
Inaccessible Pore Water
Figure3.1
Porewaterinbiomasssubstrateisinaccessiblewhentheprobemoleculecannot
enterthepore.
initial substrate will contribute to the dilution. The water present in the pores that is
not accessible to the probe molecules will not contribute to dilution. As a result, the
measured concentration of the probe molecule in the final substrate mixture depends on
the pore size and volume distribution. Using a set of different solute (probe molecule)
solutions with various molecule sizes, the substrate pore size and volume distribution
can be determined by
w
w
+
w
ac
·
c
i
=
w
w
+
(q
−
w
in
)
·
c
i
c
f
=
(3.1)
where
c
f
and
c
i
are the final and initial probe concentrations,
w
is the weight of the probe molecule solution,
w
ac
and
w
in
are the weight of water accessible and inaccessible to the probe
molecule in the wet pulp, respectively, and
q
is the weight of water in the wet pulp
(w
ac
=
q
−
w
in
)
.
Therefore,
w
in
, the pore water per gram of biomass that is inaccessible to a probe
molecule, is
1
w
in
p
=
w
+
q
p
w
w
+
q
×
c
i
c
f
W
in
=
−
(3.2)
where
p
is the weight of dry biomass sampled.
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