Environmental Engineering Reference
In-Depth Information
N
S
.
.
.
S
.
N
.
N
N
SR
S
r.t.
+2
Co
Co salt
S
N
N
S
N
figure 7.23
Synthesis of nano dithiocarbamate (DTC) complex.
results. In addition, a nano DTC complex was prepared (Fig. 7.23) by reaction between DTC and a metal salt under ultrasound
irradiation [58]. The antibacterial activity of its NP derivatives was tested against microorganisms (
E. coli
,
Klebsiella
pneumoniae
,
S. aureus
, and
Bacillus subtilis
) using the disk diffusion method and compared with non-nano conditions. The
compounds showed significant antibacterial activity against bacterial strains within the zone of inhibition, 23 mm at MIC of
30.0 µg/disk.
7.7
p-CoNtaiNiNg ligaNds
In addition to nanocomposites with sulfur-containing ligands, use of phosphorus-containing ligands in environmental appli-
cations as nanocomposites or their precursors is rare. Thus, the nanostructured conjugated polymer poly[1,1′-bis(ethynyl)-4,4′-
biphenyl-(bis-tributylphosphine)Pd(II)], known as Pd-diethynylbiphenyl (DeBP), and the hybrid system Pd/Pd-DeBP,
obtained by the dispersion of Pd(0) nanoclusters into the organometallic conjugated polymer Pd-DeBP, was studied as an
active membrane for the development of surface acoustic wave (SAW)-based chemical sensors [59]. The sensors based on
Pd-DeBP and Pd/Pd-DeBP membranes showed an rh (relative humidity) sensitivity of 600 and 320 hz/rh%, and a h
2
sensitivity of 650 and 670 hz/ppm, respectively. These values, compared with literature data, showed an enhancement of
sensitivity in the low rh range of 0-30%. There is a strong chelating ability between phosphates and metal ions that can be
used for generating biosensors. Thus, a porous nanomaterial on the basis of zirconium phytate (derivative of phytic acid,
Fig. 7.24) was synthesized [60] by direct precipitation, and its nanoporous film was employed as a substrate for making an
horseradish peroxidase (hrP)-based biosensor by the drop-coating method and investigating the electrochemical behavior of
enzyme. It was shown that the absorbed hrP retained its bioactivity and realized direct electron transfer due to improved
biocompatibility of zirconium phytate. Moreover, the biosensor displayed good bioelectrocatalytic ability toward the reduction
of h
2
O
2
with a linear response to h
2
O
2
over a concentration range from 6.67 × 10
−7
to 6 × 10
−6
mol/l, and a detection limit of
5.3 × 10
−7
mol/l at a signal to noise ratio (S/N) = 3. This biosensor exhibited a low detection limit, high enzymic activity, and
good reproducibility and stability. Silica polyamine composites (SPC) made from silanized amorphous nanoporous silica gel
and poly(allylamine) (BP-1) were functionalized [61] with phosphorus acid using the Mannich reaction, resulting in a
phosphonic acid-modified composite (BPAP). Zr(IV) was immobilized on BPAP with a loading of 1.12 mmol/g. Zr loading
was analyzed by mass gain, ICP/atomic emission spectrometry (AeS), and scanning electron microscopy (SeM)/dispersive
x-ray spectroscopy (eDx). Arsenate anions were found to be strongly adsorbed on the ZrBPAP composite at ph 2-8, while
arsenite only adsorbed well at ph 10. The sorption mechanism (a chelation between arsenate or arsenite and the Zr(IV)-
phosphonic acid complex of BPAP) is discussed.
