Chemistry Reference
In-Depth Information
during the treatment, by means of quadrupole time-of-flight tandem mass spectrometry coupled to ultra-high
performance liquid chromatography system.
19.9
Continuous monitoring of photocatalytic treatment
In a work reported several years ago [77] the continuous flow degradation of carbaryl under UV light
irradiation using a pumped TiO
2
slurry was examined. Other different manifolds were successively developed
and proposed for the photo-assisted catalytic detoxification of propoxur [78], resorcinol [79] and formetanate
[80] and of the reagents employed for their colourimetric determinations.
The flow injection approach can be also exploited for the monitoring of photocatalytic treatments of
laboratory wastes, performed in batch photoreactors. For example, the degradation of aqueous wastes
containing low concentrations of the pesticide dicamba has been followed continuously using a suitable flow-
injection manifold [81] allowing a frequent sampling of low volumes of dispersion (ca. 300
μ
l) and the
on-line filtration of TiO
2
before flowing through the UV detector.
The pesticide degradation was followed at two wavelengths (220 nm and 274 nm), corresponding to the
maximum of the dicamba UV-Vis spectrum. The measurements made at the shorter wavelength evidenced
that there is a neat removal (after ca. 75 min) of the herbicide and its by-products.
The described on-line procedure can be proposed in many cases as a suitable and cheap tool for monitoring
the photocatalytic degradation process and for a rapid evaluation of the main experimental parameters
affecting the treatment.
References
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