Reusability Of Zinc Oxide Nanorod For Photocatalytic Decomposition Of Rhodamine B Dye After Copper Metal Deposition
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Date
2018-12-01
Authors
Le, Anh Thi
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Advanced oxidation process based on semiconductor photocatalysts is an
emerging technique for wastewater treatment. However, the lifetime of these
semiconductor photocatalysts is yet to be fully studied. After heavy metal removal,
most active sites of catalyst are blocked by heavy metal. Therefore, it affects the
subsequent photocatalytic performance differently in organic dye removal. In this
work, ZnO nanorods (NRs) and nanodisks (NDs) were synthesized by precipitation
method and evaluate the photocatalytic activity to degrade Rhodamine B dye after
heavy metal deposition. The average length and diameter of ZnO NRs were 497.34 ±
15.55 nm and 75.78 ± 10.39 nm, respectively. The ZnO NDs have average diameter
of 2.12 ± 0.39 µm and thickness of 74.91 ± 17.67 nm. The photodegradation of RhB
dye by ZnO particles followed first-order kinetic reaction. ZnO NRs removed
effectively heavy metal ions such as Cu(II), Ag(I) and Pb(II) ions with efficiency of
100%, 97.92% and 85.18%, respectively under exposure of UV light for 1 hour.
However, poor removal efficiency, i.e. 14.83%, 8.62%, 7.23% and 4.76%, respectively
was observed for Cr(VI), Mn(II), Cd(II) and Ni(II). These heavy metal ions were
removed in the forms of metals or metal oxide via reduction/oxidation or adsorption
mechanisms. The degradation efficiencies of RhB dye by Cu/ZnO, Ag/ZnO, Mn/ZnO,
Cd/ZnO and Ni/ZnO hybrid particles were better than ZnO particles but not the case
of Pb/ZnO and Cr/ZnO hybrid particles. In conclusion, the ZnO NRs in general
showed a remarkable ability to degrade RhB dye under UV irradiation after heavy
metal deposition.