102
Tecnología y Ciencias del Agua
, vol. VIII, núm. 2, marzo-abril de 2017, pp. 93-103
Song & Song,
Kinetics and influential factors of nanoscale iron-facilitated nitrate-nitrogen removal
•
ISSN 2007-2422
is a strong reducing agent of substances that
can be easily reduced, such as H
+
, CO
3
2-
, SO
4
2-
, NO
3
-
, and O
2
(Schlieker
et al
., 2000). In the
Fe–NO
3
-
system, Fe
0
acts as the reductant and
loses electrons, while NO
3
-
acts as the oxidant
and gains electrons. The NO
3
-
gains electrons
released by the Fe
0
as well as the oxidation
products of the Fe, including Fe
2 +
and H
2
.
According to thermodynamics, Fe
0
could be
converted into Fe
2+
after losing electrons,
and NO
3
-
is reduced to N
2
. Therefore, Fe
0
can
completely reduce NO
3
-
, but the reduction
products of NO
3
-
are determined by the reac-
tion conditions (Agrawal & Tratnyek, 1996).
Conclusions
1. When nitrate-nitrogen removal was per-
formed with different concentrations of
nanoscale iron, lower nitrate nitrogen con-
centrations were associated with increased
removal. This was primarily influenced by
the adsorption site of the nanoscale iron.
2. Under acidic conditions, the nanoscale iron
exhibited the highest adsorption ability and
maximum nitrate-nitrogen removal when
the pH of the solution was 2.0.
3. The temperature of the solution influenced
the reaction rate. The kinetic equation
C
t
=
C
0
-
k
t
C
2
a
/1 +
k
t
C
a
was developed based
on the experimental data. According to the
equation, the reaction rate constant k was
highest with a value of 0.014 mg/(l/min) at
50 ˚C.
4. By calculating the value of the reaction rate
constant k at different temperatures, the reac-
tion activation energy
Ea
was determined to
be approximately 17.18 kJ/mol. The results
indicated that the reaction was primarily
affected by the mass transfer of the solution.
5. Under neutral conditions, the reaction
product of the nitrate nitrogen solution was
ammonia.
Acknowledgments
This project was supported by the National Natural Science
Foundation of China (40871005). This project was supported
by the “Simulation and regulation of nitrogen and phos-
phorus transfer in small drainage basins on the periphery
of urban areas” research program, which is funded by the
Thirteenth Five-Year Scientific Research Program of the Jilin
Province Department of Education. This project was funded
by the Scientific Research Foundation of the Changchun
University of Science and Technology.
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