Environmental Engineering Reference
In-Depth Information
100 nm
figure 11.3
Typical transmission electron microscopy (TEM) micrograph of NCMC (Ti).
11.4.2
laboratory tests
The photodegradation ability of aldrin, lindane, DDT, and PCBs by NCMC (Ti) was investigated in laboratory conditions.
Colloidal solutions of NCMC (Ti) were added to two Petri dishes containing water with aldrin. The first sample was irradi-
ated by UV lamp. The second Petri dish was irradiated by sunlight for 2 days from 11 a.m. to 4 p.m. The third sample did not
contain NCMC (Ti) and was irradiated by a UV lamp. Concentrations of NCMC (Ti) and aldrin in solutions were 5 and 10 µg/l,
respectively. The temperature of solutions during irradiation under UV lamp was 25°C and under sunlight was 26-30°C.
Dependences of aldrin concentrations in water samples against exposure time are given in figure 11.4. The results show that
aldrin in water is degraded in 5-6 h. we did not observe any degradation of aldrin without NCMC (Ti). In another experiment,
emulsion of a fine powder of aldrin with particle size of about 10 µm was dispersed to reach a surface density 10 µg/cm
2
on the
bottom of two Petri dishes containing water and NCMC (Ti). The concentration of NCMC (Ti) was 10 µg/l, and the water
layer thickness was 5 mm. Dependences of aldrin surface density in samples irradiated by UV lamp and sunlight against
exposure time are given in figure 11.5. The results show that aldrin powder in water is degraded in 8-10 h.
for the investigating photodegradation of lindane, colloidal solutions of NCMC (Ti) were added to two Petri dishes contain-
ing water with lindane. The first sample was irradiated by UV lamp. The second Petri dish was irradiated by sunlight for 2 days
from 11 a.m. to 4 p.m. The third sample did not contain NCMC (Ti) and was irradiated by UV lamp. Concentrations of NCMC
(Ti) and lindane in solutions were 1 and 8 mg/l, respectively. The temperature of solutions during irradiation under UV lamp
was 25°C and under the sunlight it was 26-30°C. The dependencies of lindane concentrations in water samples against exposure
time are given in figure 11.6. The results show that lindane in water is degraded in 6-7 h. we did not observe any degradation
of lindane without NCMC (Ti). Trichlorobenzenes are formed as reaction products during the first 2 h of irradiation, but they
are destroyed 3 h after the start of the irradiation process. In another experiment, a fine powder of lindane with particle size of
about 10 µm was dispersed to reach a surface density of about 8 mg/cm
2
on the bottom of two Petri dishes containing water and
NCMC (Ti). The concentration of NCMC (Ti) was 1 mg/l, and the water layer thickness was 5 mm. Dependences of lindane
surface density in samples irradiated by UV lamp and sunlight against the exposure time are given in figure 11.7. The results
show that lindane powder in water is degraded in 8-10 h.
we investigated the photodegradation of DDT powder with particle size of about 10 µm under UV lamp and sunlight. The
powder was dispersed on the bottom of two Petri dishes containing water and NCMC (Ti). The concentration of NCMC (Ti)
was 1 mg/l, the thickness of water was 5 mm, and the surface density of the powder was about 5 mg/cm
2
. Dependences of DDT
surface density in samples irradiated by UV lamp and sunlight against exposure time are given in figure 11.8. The results show
that the surface density of DDT powder in water decreases by two times in 8-10 h.
