Preparation of alumina-zirconia (Al-Zr) ceramic
nanofiltration (NF) membrane for the removal
of uranium in aquatic system
Youngkun Chung, Yeo-Myeong Yun, Yeo-Jin Kim, Yu Sik Hwang
and Seoktae Kang
ABSTRACT
In this research, ceramic nanofiltration (NF) membranes were prepared by depositing alumina-
zirconia (Al-Zr) nanoparticles into the pores of ceramic ultrafiltration (UF) membranes for the removal
of radioactive uranium in an aquatic system. The modified ceramic membranes showed NF
membrane performance with around 1,000 Da molecular weight cut-off (MWCO) and 58% CaCl
2
rejection. The removal efficiencies of uranium species by these successfully modified ceramic NF
membranes exhibited differences depending on the pH conditions (pH 5.0, 7.4, and 10.0), and
achieved the highest rejection of 91% at pH 7.4. This behavior is due to the dominant aqueous
species of uranium in pH 7.4, (UO
2
)
2
CO
3
(OH
3
)
, which has the largest molecular weight among the
conditions and the negatively charged species having electrostatic attraction to the positively
charged ceramic NF membranes. The ceramic NF membrane prepared here is expected to be
feasible in the advanced water treatment process to remove radioactive compounds.
Youngkun Chung
Yeo-Myeong Yun
Seoktae Kang (corresponding author)
Department of Civil and Environmental
Engineering,
Korea Advanced Institute of Science and
Technology (KAIST),
291 Daehak-ro, Yuseong-gu, Daejeon 305-701,
Republic of Korea
E-mail: stkang@kaist.ac.kr
Yeo-Jin Kim
Center for Membranes, Advanced Materials
Division,
Korea Research Institute of Chemical Technology,
141 Gajeong-ro, Yuseong-gu, Daejeon 34114,
Republic of Korea
Yu Sik Hwang
Future Environmental Research Center,
Korea Institute of Toxicology,
Jinju 660-844,
Republic of Korea
Key words | ceramic nanofiltration (NF) membrane, filtration-coating, uranium
INTRODUCTION
In nature, uranium, known as one of the most common radio-
active materials, is often found in trace amounts which are
not of concern with regard to radiation protection. For
decades, however, anthropogenic activities such as mining,
milling, nuclear testing, and the disposal of spent nuclear
fuel have led to the accumulation of uranium in groundwater,
thus posing a public health risk through the drinking water
supply system. The maximum acceptable uranium concen-
tration in drinking water recommended by the World
Health Organization (WHO) is 30 μg/L, and the maximum
contaminant level (MCL) regulated by the United States
Environmental Protection Agency (USEPA) for standard
drinking water is also 30 μg/L (Broder & Alireza ).
To remove uranium in an aquatic system, various
methods of water treatment process can be used, such as
adsorption, ion exchange, sedimentation, thermal evapor-
ation, and membrane technologies (Kang et al. ;
Keum et al. ). Among these, membrane technologies,
especially nanofiltration (NF) and reverse osmosis (RO),
are most feasible, particularly for a wide range of contami-
nants, including uranium (Choong et al. ). NF
membranes are a proven technology, providing higher
levels of flux than RO at lower operating pressures. Because
of ease of fabrication, polymeric NF membranes have been
increasingly applied for the treatment of low molecular
weight dissolved organic matter and multivalent ions such
as Ca
2þ
and Mg
2þ
by the mechanism of size and electro-
static exclusion (Chakrabortty et al. ). However, one
significant limitation is that polymeric NF membranes can
easily be damaged by high-energy radiation such as
789 © IWA Publishing 2019 Water Supply | 19.3 | 2019
doi: 10.2166/ws.2018.123
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