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International Journal of Environment Science and Technology
Center for Environment and Energy Research and Studies (CEERS)
ISSN: 1735-1472 EISSN: 1735-1472
Vol. 13, No. 3, 2016, pp. 907-926
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Bioline Code: st16087
Full paper language: English
Document type: Research Article
Document available free of charge
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International Journal of Environment Science and Technology, Vol. 13, No. 3, 2016, pp. 907-926
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Role of bentonite adsorbent sub-layer in the photocatalyticadsorptive removal of methylene blue by the immobilized TiO2/bentonite system
Ngoh, Y. S. & Nawi, M. A.
Abstract
An immobilized clay composite (BEN–PVAG)
on a glass plate (GP) was fabricated using bentonite
powder (BEN) and glutaraldehyde cross-linked polyvinyl
alcohol (PVAG) as the adsorbent and adhesive, respectively.
The immobilized bentonite composite (BEN–
PVAG) was characterized using SEM, EDX, FTIR, and
BET analysis. The adsorption capacity of BEN–PVAG was
examined using methylene blue (MB) as the model pollutant.
The results indicated that the adsorption of MB onto
BEN–PVAG obeyed pseudo-second-order kinetics. In
addition, the adsorption of MB by the immobilized BEN–
PVAG was controlled by intra-particle diffusion. In contrast,
the adsorption of MB by the suspended BEN–PVAG
composite was dominated by film diffusion. The immobilized
BEN–PVAG was then applied as the adsorbent sublayer
for the fabrication of P-25TiO2/BEN–PVAG/GP
bilayer system where P-25TiO2 was deposited as the top
layer. The fabricated bilayer system exhibited synergistic
photocatalytic-adsorptive removal of MB upon irradiation
with a light source, while experiment in the dark yielded
only adsorption process. The rate of the synergistic photocatalytic-
adsorptive removal of MB by the P-25TiO2/
BEN–PVAG/GP was 5.3 times faster than the suspended
P-25TiO2. The result implied the positive impact of the
BEN–PVAG adsorbent sub-layer on the immobilized
P-25TiO2 photocatalyst. Most important, the immobilized
P-25TiO2/BEN–PVAG/GP provided a convenient reuse of
the catalyst over time where the treated water could be
directly discharged without the need of filtration.
Keywords
Kinetics; Bentonite; Immobilization; Methylene blue; TiO2
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