Biotechnological potential of Azolla ﬁliculoides for biosorption of Cs and Sr:
Application of micro-PIXE for measurement of biosorption
Saeid Ghorbanzadeh Mashkani
, Parisa Tajer Mohammad Ghazvini
Department of Nuclear Biotechnology, Nuclear Science Research School, Nuclear Science and Technology Research Institute, North Karegar Street, Tehran 11365-3486, Iran
Department of Microbiology, Faculty of Science, Az-Zahra University, Tehran, Iran
Received 7 July 2008
Received in revised form 12 October 2008
Accepted 13 October 2008
Available online 2 December 2008
The presence of Cs and Sr in culture medium of Azolla ﬁliculoides caused about 27.4% and 46.3% inhibition
of biomass growth, respectively, in comparison to A. ﬁliculoides control weight which had not metals. Bio-
sorption batch experiments were conducted to determine the Cs and Sr binding ability of native biomass
and chemically modiﬁed biosorbents derived from Azolla namely ferrocyanide Azolla sorbents type 1 and
type 2 (FAS1 and FAS2) and hydrogen peroxide Azolla sorbent (HAS). The best Cs and Sr removal results
were obtained when A. ﬁliculoides was treated by 2 M MgCl
and 30 ml H
8 mM at pH 7 for 12 h and it
was then washed by NaOH solution at pH 10.5 for 6 h. Pretreatment of Azolla have been suggested to
modify the surface characteristics which could improve biosorption process. The binding of Cs and Sr
on the cell wall of Azolla was studied with micro-PIXE and FT-IR.
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Heavy metals and radionuclides contaminations are the result
of industrial activities, mill tailing, nuclear power testing
(Mosquera et al., 2006; Mahara, 1993), nuclear waste disposal
(Gauthier-Lafaye, 2002; Whicker et al., 1990) and accidents result-
ing from nuclear power generation (Clark and Smith, 1988;
Konshin, 1992). An accident of this nature occurred at the Cher-
nobyl Nuclear Power Station on April 26, 1986 (Anspaugh et al.,
Sr are the most widespread radionuclides in
the environment (Mosquera et al., 2006). Contamination of soils
with typical ﬁssion product radionuclides, such as
has persisted for far longer than was originally expected.
Sr have been matter of serious concern because of
long halﬂife and high water solubility. Thus, hazardous quantities
Sr will remain in the environment for centuries
and living organisms easily absorb
Sr mistaking these
for harmless essential cations (Jalali-Rad et al., 2004).
Although cleanup is necessary to prevent any further discharge
of contaminated wastes into the environment, a technology needs
to be developed that is cost effective for industry to use. Methods
traditionally employed for wastewater remediation consist of re-
moval of metals by ﬁltration, ﬂocculation, activated charcoal and
ion exchange resins (Karthikeyan et al., 2007; Vijayaraghavan
et al., 2006; Volesky, 2001). However, because of the high cost of
these methods, development of a more cost effective remediation
system is necessary.
There has been a tremendous amount of attention given to the
use of biological systems for removal of radionuclides and heavy
metals from solutions. (Ghorbanzadeh Mashkani et al., 2009;
Malekzadeh et al., 2007; Macaskie et al., 2007; Horsfall et al.,
2006; Kumar and Bandyopadhyay, 2006; Volesky, 2001; Yang
and Volesky, 1999; Veglio and Beolchini, 1997; Xie et al., 1996).
More recently, phytoremediation has emerged as one of the
alternative technologies for removing pollutants from the environ-
ment (Pavasant et al., 2006; Tien, 2002; Antunes et al., 2001; Yang
and Volesky, 1999; Zhao et al., 1999; Zhao and Duncan, 1998).
Interest in using plants for environmental remediation is increas-
ing due to their natural capacity to accumulate heavy metals and
degrade organic compounds (Pavasant et al., 2006; Cohen et al.,
2002). Although the fact that the marine algae are capable of bio-
logically concentrating heavy and toxic metals has been known
for long time (Jalali-Rad et al., 2004; Tien, 2002; Yang and Volesky,
1999), the biosorption of Cs and Sr by aquatic plants such as Azolla
sp. has rarely been reported (Jalali-Rad et al., 2004). Azolla develops
a symbiotic relationship with cyanobacteria. Azolla is found in
ponds, ditches and wetlands of warm temperate and tropical re-
gions throughout the world. It has been used as a fertilizer in
botanical gardens because of nitrogen-ﬁxing capability. Azolla has
been used for several decades as green manure in rice ﬁelds (Peters
and Meeks, 1989). On the other hand, it has negative effects on the
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* Corresponding author. Tel.: +98 9125485818; fax: +98 21 88009080.
E-mail address: email@example.com (S. Ghorbanzadeh Mashkani).
Bioresource Technology 100 (2009) 1915–1921
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