The measurement was done using the device described in the previous section.
The migration curves obtained at selected times of the experiment were compared
with an experiment performed under the same conditions in a standard
one-dimensional column with an internal diameter of 20 mm. A comparison of the
migration curves is displayed in Figs. 30.7 and 30.8. The results are plotted on
separate axes of both graphs because a detector with different sensitivity was used
for each column.
The cascade column simulates the process during nZVI injection into the well
more precisely than the standard one-dimensional column. However, experiments in
standard columns with constant flow are much less demanding for the material (sand
or soil filling, nZVI suspension, eventual surface modifiers, etc.). For this reason, the
one-dimensional column is more suitable for comparing the migration properties of
different types of nZVI while the results obtained using the cascade column are
suitable for more realistic testing of the migration of nZVI.
Fig. 30.6 (a) Cascade column with visible inner tube serving as a technical channel for the inlet
and outlet of the suspension that is pumped into the column through series of thin tubes. (b) Cascade
column during an experiment where the black zone indicates mobility of nZVI
30 Tool I: Characterization of nZVI Mobility in 1D and Cascade. . .
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