Agriculture Reference
In-Depth Information
iso-alcohol in NF
4
-H
2
O solution to prepare a nanocrystalline catalyst with high
catalytic activity. The results obtained showed that F doping increased anatase
crystallinity and suppressed the generation of brookite and transition from anatase
to rutile with increasing doping dosage of F. In addition, the catalytic activity of this
photocatalyst on acetone in air was higher than that of P-25, the width of the band
gap was significantly decreased, and a strong absorption performance was noted in
the UV-vis range.
12.7 Photocatalytic Degradation of Antibiotics
by Nano-TiO
2
Numerous studies have shown that unlike conventional water treatment technolo-
gies, advanced oxidation technologies can remove organic pollutants with chemical
stability and low biodegradability in a short period of time and are considered as
very promising treatment methods. Photocatalytic oxidation technology can effec-
tively and rapidly remove trace organic pollutants in mild environment with no
secondary pollution. In recent years, many scholars have conducted studies on
photocatalytic degradation of a variety of antibiotics, such as amoxicillin (AMX),
ampicillin (AMP), cloxacillin (CLX), SMX, TC, chloramphenicol, sulfamethazine
(SMZ), and other sulfa drugs. In addition, investigations on the conditions of
photocatalytic degradation, intermediate generation, degradation pathway, degra-
dation dynamics, and other aspects have drawn much attention.
In the photocatalytic antibiotic degradation process, many environmental factors
affect the degradation efficiency, including the use of catalysts and their concen-
trations, wavelength of light used, irradiation time, pH, H
2
O
2
, initial contamination
concentration, and other active parameters. Furthermore, the photocatalytic degra-
dation process produces a variety of plasma, whose status and quantity are affected
by the pH value, which, in turn, significantly influence the degradation perfor-
mance. The molecule of antibiotics such sulfonamides, TCs, and fluoroquinolones
contains acid and alkali dissociation groups that can be remarkably disturbed. These
dissociating groups occur in different forms in the solution at different pH, resulting
in significantly different chemical reactivities. However, the effect of solution pH
on the photochemical behavior of different types of antibiotics is varied, because
different forms of the antibiotic molecule have different absorption spectra and
photolysis quantum yield. As a result, a difference in the rate constant of photolysis
occurs, indicating that the photochemical behavior of antibiotics is influenced by
the pH-affected status and chemical properties of the antibiotics.
Photocatalyst has an integral role in the photocatalytic reaction. Often, previous
studies have explored the effect of the concentration of photocatalyst on the
efficiency of photocatalytic antibiotics degradation and tried to determine the
optimal concentration. Numerous studies have reported an optimal TiO
2
concen-
tration and observed that the degradation rate of pollutants increased with the
