Photocatalytic Degradation of Imidacloprid by Phosphotungstic Acid
age of the prepared HPW/MCM-41 is neglected, sug-
gesting the strong interactions between HPW Keggin
unit and the support MCM-41 ensure the little leaching
of the Keggin anions from MCM-41 (Figure 10).
perfect microenvironment for the photocatalytic reac-
tion of imidacloprid by HPW Keggin anions.
Conclusions
A series of solid mesoporous HPW/MCM-41 cata-
lysts with different loading levels are prepared by im-
pregnation method. The composites have regular and
uniform mesopores with average pore diameter above 2
nm. Their BET specific surface areas are much higher
than that of starting phosphotungstic acid. The prepared
heterogeneous catalysts exhibit high photocatalytic ac-
tivity in degradation of a durable pesticide imidacloprid
under irradiation of near-visible 365 nm light. The in-
fluences of loading level, calcined temperature and the
amount of catalysts are discussed and compared. For 50
mL of imidacloprid (10 mg/L), in the optimal reaction
conditions, conversion of imidacloprid using 20 mg of
HPW/MCM-41 with 50 wt% loading level and calcined
at 300 ℃ reaches 58.0% after 5 h irradiation. The high
photocatlytic activity of composites mainly comes from
the uniform mesopores and large specific surface area of
the catalysts.
Figure 9 Influence of the amount of the catalysts on degrada-
tion of imidacloprid. (a)—(d) are 20, 30, 40 and 10 mg, respec-
tively.
Acknowledgement
This work was supported by Institute of Chemicl
Materials, China Academy of Engineering Physics.
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