NAMS 2002 Workshop - ICOM 2008

Nanostructured Membranes II - 7
Tuesday July 15, 12:00 PM-12:30 PM, Moloka’i
Multifunctional ultrathin TiO2 Nanowire Ultrafiltration Membrane for Water
Treatment
X. Zhang (Speaker), Nanyang Technological University, Singapore
A. Du, Nanyang Technological University, Singapore
J. Pan, Nanyang Technological University, Singapore
D. Sun, Nanyang Technological University, Singapore, ddsun@ntu.edu.sg
J. Leckie, Stanford University, Stanford, CA, USA
For the last two decades, micro/ultra filtration membranes have been used as an
advanced water treatment process for producing high quality drinking water with
small footprint 1 . Recently, inorganic membranes have attracted considerable
attention due to their excellent thermal, chemical, mechanical stability 2 . Among
the materials used for the preparation of inorganic membranes, TiO2 is unique
due to its excellent performance under UV irradiation on mineralization of virtually
all organic compounds 3, 4 . So, TiO2 membrane can provide concurrent filtration
and photocatalytic oxidation. Recently various morphologies of 1 dimensional
(1D) nanostructured TiO2, including nanowires, nanofibers, nanorods and
nanotubes, have been prepared by means of chemical or physical methods 5-11 .
These nanostructured TiO2 photocatalysts exhibit superior photocatalytic
efficiency relative to conventional bulk materials as a result of its larger surface
area and presence of quantum size effect.
In this paper, a new kind of multifunctional ultrathin TiO2 nanowire UF membrane
was fabricated using a method of hydrothermal syntheses-filtration. The
fabricated UF membrane has a supporting layer of glass fiber and a funcational
layer of ultrafine TiO2 nanowire. These TiO2 nanowires had typical diameter of
several micrometers. Beside of good performance on separation, the TiO2
membrane exited excellent photocatalytic activity on degradation of methylene
blue (MB). The nanowire membrane has shown unusual potentials for
environmental purification.
Ultrathin TiO2 nanowires were systhesized by hydrothermal reaction. These TiO2
nanowires were assembled on glass filter by filtration with surfactant assistant.
The photocatalytic activity of the TiO2 nanowire membrane were evaluated with
MB and humic acid (HA) as model pollutants.
FESEM observation revealed that the TiO2 nanowire functional layer of the
membrane was formed by overlap and interpenetration of long TiO2 nanowires
with typical lengths of several micrometers. The surface of membrane was very
flat. TEM observations revealed that the diameters of TiO2 nanowires were less