Title:Photocatalytic Reduction of Aqueous Mercury (II) Using Hybrid WO3-TiO2 Nanotubes Film
VOLUME: 13 ISSUE: 6
Author(s):Wai Hong Lee, Swe Jyan Teh, Pui May Chou and Chin Wei Lai*
Affiliation:Nanotechnology & Catalysis Research Centre (NANOCAT), 3rd Floor, Block A, Institute of Postgraduate Studies (IPS), University of Malaya, 50603 Kuala Lumpur, Nanotechnology & Catalysis Research Centre (NANOCAT), 3rd Floor, Block A, Institute of Postgraduate Studies (IPS), University of Malaya, 50603 Kuala Lumpur, School of Engineering, Taylor's University Lakeside Campus, No. 1, Jalan Taylor's, 47500 Subang Jaya, Selangor Darul Ehsan, Nanotechnology & Catalysis Research Centre (NANOCAT), 3rd Floor, Block A, Institute of Postgraduate Studies (IPS), University of Malaya, 50603 Kuala Lumpur
Keywords:WO3-loaded TiO2 nanotubes, anodization, aspect ratio, geometric surface area factor, photocatalytic reduction of
mercury (II), electrochemical anodization.
Abstract:Background: Mercury pollution has become a serious and enduring threat to the environment.
It has affected the organisms along the food chain, including humans. Thus, it is necessary to
design an effective mercury removal system to overcome the huge threat of mercury pollution. Our
study aim is to optimize the anodization duration of as-prepared WO3-loaded TiO2 nanotubes for
improving their photocatalytic mercury (II) reduction performance.
Method: Hybrid WO3-TiO2 nanotubes film were successfully formed via electrochemical anodization
at applied potential of 40 V in ethylene glycol organic electrolyte containing 1 vol% of hydrogen
peroxide (H2O2) and 0.3 wt% ammonium fluoride (NH4F) by varying the anodization time from 15
up to 120 minutes. A tungsten electrode was chosen as the cathode as an innovative and convenient
approach to hybridize WO3 with TiO2 nanotubes film.
Results: During electrochemical anodization, W6+ ions dissolve from the cathode into the electrolyte
solution, migrate towards the titanium foil and are deposited evenly on the Ti foil. This study recorded
a maximum photocatalytic mercury (II) reduction performance of 91% (with exposure to 96
W UV-B Germicidal light irradiation for 120 minutes) in the presence of WO3-TiO2 nanotubes film
with the highest aspect ratio (53.04) and geometric surface area factor (345.68).
Conclusion: The main reason might be attributed to the high specific surface area nanotubes architecture
performed strong light scattering effects as well as better incident light absorption from any
direction to trigger more charge carriers for photocatalytic reduction of mercury(II) into elemental
mercury. WO3 acted as an effective mediator to trap the photo-induced electrons from the TiO2, by
contributing intermediate energy band levels below the conduction band of TiO2.
