Nanoparticles for Trace Analysis of Toxins: Present and Future Scenario - Advanced Materials for Agriculture, Food and Environmental Safety - page 182

particulates and geological samples; and also physical modii cation with
diethyldithiocarbamate (DDTC), 1-(2-pyridylazo)-2-naphthol (PAN),
dithizone and 8-hydroxyquinolone used for the separation and extrac-
tion of Cr,Cu, Pb, Zn,Fe, Al, Y, Yb from natural, waste and environmental
water samples, biological samples and also in food samples [26-34].
Since the expression of super-hydrophilicity with TiO 2 photocatalyst
was presented in 1997 by Hashimoto et al. research into this feature has
been active. Consequently, it has been increasingly applied to fog-prooi ng
and self-cleaning applications for mirrors, including road mirrors (curve
mirrors) and door mirrors on cars, as well as window glass panels. Since
the hydrophilicity of TiO 2 photocatalysts is more positively maintained by
the addition of SiO 2 or a more porous structure of TiO 2 particles, improve-
ment in the composition and layer-forming method for TiO 2 photocata-
lysts is now underway. Air purii cation is one example of the most advanced
application of TiO 2 photocatalysts. For example, photocatalysts are used in
deodorizing i lters in air-purii ers, incorporating UV lamps to eliminate
aldehyde or VOC in indoor air. Since then, there has been a report con-
cerning the successful elimination of low-concentration NOx in outdoor
environments. A TiO 2 photocatalyst oxidizes NO into NO 2 and eventually
into NO 3 _ , hence removing NO from the air [35]. Nanogold supported on
TiO 2 -coated glass i ber was used for removing toxic CO gas from air. h e
outstanding catalytic activities of nanogold for oxidizing CO at low tem-
perature, and various reactions of nanogold catalysts have been studied.
h ese include CO oxidation, preferential oxidation of CO in the presence
of excess hydrogen (PROX), water-gas shit reaction (WGSR), hydrogena-
tion and oxidation.

7.3 Gold Nanoparticles for Nanoremediation

Gold nanoparticles (AuNPs), one of the wide varieties of core materials
available, coupled with tunable surface properties in the form of inorganic
or inorganic-organic hybrid, have been reported as an excellent platform
for a broad range of analytical methods. h e modii cation of the Au sur-
face with appropriate chemical species can improve the separation and
preconcentration ei ciency, analytical selectivity, and method reliability.
Because of their high surface-to-volume ratio, easy surface modii cation,
and simple synthesis methods, gold nanoparticles (AuNPs) are becom-
ing an attractive material as an alternative to conventional solvent extrac-
tion and solid-phase extraction. h rough covalent bond formation (Au-S
bonds), electrostatic attraction, hydrophobic adsorption, and molecular