Environmental Engineering Reference
In-Depth Information
the nanocrystals vary between 25 and 60 nm. In addition, the surface area of the GNP was
recorded as 56 m
2
/g .
37.3.2.4 Silver Nanoparticles
Figure 37.5 shows an XRD pattern that can be indexed on the basis of the structure of silver.
The XRD pattern thus obtained clearly shows [111,200,220], and [311] planes, and demon-
strates that the synthesized AgNPs by the
Bacillus
were crystalline in nature. The diffrac-
tion peaks were found to be broad around their bases, indicating that the silver particles
are nanoscale. The peak broadening at half-maximum intensity of the XRD lines is due to
a reduction in crystallite size, lattening, and microstrains within the diffracting domains.
The TEM image of a nanoparticle that was synthesized by
B. megaterium
indicated that the
nanoparticles were in the size range of 10-20 nm and well crystalline [57]. In addition, the
surface area of the AgNP was recorded as 25.0 m
2
/g .
Figure 37.6 shows the appearance of the 1 g/l of each nanoparticle suspension at 0 day
and after 30 days. According to visual observations, there is no color change after 30 days
(a)
(b)
111
1000
200
200
311
220
500
222
10 nm
0
0.4
0.6
0.8
1.0
b (1/A)
FIGURE 37.5
XRD pattern (a) and TEM image (b) for synthesized AgNPs. Scale bar represents 10 nm.
(a)
(b)
(i)
(ii)
(iii)
(iv)
FIGURE 37.6
Photographs of changing colors in different 1 g/l nanoparticle suspension: (a) initial appearance and (b) after 1
month of (i) S-NZVI, (ii) IONP, (iii) GNP, and (iv) AgNP.
