Environmental Engineering Reference
Preparation of Magnetic Nanoparticles (MNPs)
The basic principle of our method for development of an MNP was reduction of ferrous
sulfate with ammonia solution in presence of potassium nitrate. For this 0.1 g of ferrous
sulfate was dissolved in 100
L MiliQ water. In a separate container 0.1 g of potassium
nitrate was dissolved in 1,000
L of ammonia solution. Both solutions were mixed and
instantly vortexed (mixed vigorously using a cyclomixer) for 10 min. During addition
of ammonia to the ferrous solution the solution fi rst turns green and after vigorous mix-
ing black slurry is generated. Now the generated MNPs were maintained in a highly
reducing (basic) medium for long storage and before application the MNPs were
washed several times with MiliQ water. The MNPs are separated from impurities and
excess ammonia by means of magnetic separation. After removal of impurities the
MNPs are resuspended in 2,000
L MiliQ water. These MNPs could be stored for at
least a month in an airtight container without considerable oxidation.
Synthesis of Glutathione (GSH) Coated Iron Nanoparticle
100 mL 30 mM glutathione was prepared in water (pH
9.0 ± 0.5) and under constant
steering condition (2,000 rpm) 1 g of as-synthesized iron nanoparticles were added.
It was kept under constant steering condition for 120 min at room temperature. The
glutathione coated iron nanoparticles were separated from excess unbound glutathione
using magnetic decantation and washing with double distilled water for three times.
Synthesis of Sodium Dodecyl Sulfate (SDS) Coated Iron
For SDS coating 5 % (w/v) SDS solution was prepared in 100 mL water and to it 1 g
of iron nanoparticles were added slowly. During addition of the iron nanoparticles
the SDS solution was kept under steering condition (at 515 rpm). After 120 min of
steering the SDS coated iron nanoparticles were separated from the excess unbound
SDS by magnetic decantation and it was washed with DDW for three to four times
for complete removal of any unbound SDS.
The comparative study on growth of bacteria under normal condition and under the
infl uence of magnetic nanoparticles has been carried out (Chatterjee et al. 2011 ).
Various concentrations of nanoparticles (i.e. 100
g/mL) were added