Photocatalytic Degradation
:
ZnO, and ZnO/SiO
2
microparticles were used as photocatalysts
respectively to degrade Methyle
ne Blue dissolved in
water. Fig
ure
5
shows the relationship between C/C
0
and irradiation time for Methylene Blue in basic
solution photocatalyzed by ZnO and ZnO/SiO
2
microparticles. Within 90 minutes, the photocatalytic
degradation of Methylene Blue is 13
and 68% in the
presence of ZnO, and ZnO/SiO
2
microparticles. This
means that the modified ZnO/SiO
2
microparticles have
higher photocatalytic activity.
Although ZnO
nanoparticles is a quite active photocatalyst, ZnO
reactions with excessive OH
-
in alkaline
medium,
threrefore leading to the failure of photocatalytic
degradation of Methylene Blue. After ZnO was
modified with SiO
2
, the stability of core/shell
structured ZnO/SiO
2
microparticles was improved due
to the reduced contact of ZnO with [OH]
−
[1