dissociated
electrons are rapidly combined easily with certain organic
compounds such as azo dye AB24, resulting in reduction of the
organic concentrations. In addition to 0.1674 g L−1 NZVI particles,
the AB24 concentration reduction curves versus time are
shown in Fig. 2 with four different initial dye concentrations.
From the figure, the dye concentrations declined very rapidly
and sharply during the first few minutes and then remained
almost unchanged. For a 100 mg L−1 initial dye concentration,
a residual of about 70% was found after the first 2 min,
promptly declining to about 30% after 15 min, and about 26%
residual after 30 min was found. It changed only till 90 min,
which implies the reductive degradation of AB24 during the
initial 15 min, after which only changes for dye removal occurred.
Except for time, the dye initial concentration is another
effect for dye removal so as to increment the residual dye concentration
by increasing from 25 to 100 mg L−1.