Thermal modification of activated carbon surface chemistry improves its capacity as redox mediator for azo dye reduction
The surface chemistry of a commercial AC (AC 0) was selectively modified, without changing significantly its textural properties, by chemical oxidation with HNO 3 ( AC HNO 3 ) and O 2 ( AC O 2 ) , and thermal treatments under H 2 ( AC H 2 ) or N 2 ( AC N 2 ) flow. The effect of modified AC on anaero...
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Published in | Journal of hazardous materials Vol. 183; no. 1; pp. 931 - 939 |
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Main Authors | , , , , , |
Format | Journal Article |
Language | English |
Published |
Kidlington
Elsevier B.V
15.11.2010
Elsevier |
Subjects | |
Online Access | Get full text |
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Summary: | The surface chemistry of a commercial AC (AC
0) was selectively modified, without changing significantly its textural properties, by chemical oxidation with HNO
3
(
AC
HNO
3
)
and O
2
(
AC
O
2
)
, and thermal treatments under H
2
(
AC
H
2
)
or N
2
(
AC
N
2
)
flow. The effect of modified AC on anaerobic chemical dye reduction was assayed with sulphide at different pH values 5, 7 and 9. Four dyes were tested: Acid Orange 7, Reactive Red 2, Mordant Yellow 10 and Direct Blue 71. Batch experiments with low amounts of AC (0.1
g
L
−1) demonstrated an increase of the first-order reduction rate constants, up to 9-fold, as compared with assays without AC. Optimum rates were obtained at pH 5 except for MY10, higher at pH 7. In general, rates increased with increasing the pH of point zero charge (pH
pzc), following the trend
AC
HNO
3
<
AC
O
2
<
AC
0
<
AC
N
2
<
AC
H
2
. The highest reduction rate was obtained for MY10 with
AC
H
2
at pH 7, which corresponded to the double, as compared with non-modified AC. In a biological system using granular biomass,
AC
H
2
also duplicated and increase 4.5-fold the decolourisation rates of MY10 and RR2, respectively. In this last experiment, reaction rate was independent of AC concentration in the tested range 0.1–0.6
g
L
−1. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0304-3894 1873-3336 |
DOI: | 10.1016/j.jhazmat.2010.08.005 |