Browsing by Author "LU, MC"

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FACTORS AFFECTING THE PHOTOCATALYTIC DEGRADATION OF DICHLORVOS OVER TITANIUM-DIOXIDE SUPPORTED ON GLASS
(1993-12-01)
LU, MC
;
ROAM, GD
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CHEN, JN
;
HUANG, CP
;
環境工程研究所
The photocatalytic degradation of organophosphorus insecticide, dichlorvos, on glass-supported titanium dioxide was investigated. The photoreactor coated with titanium dioxide was illuminated with a 20 W black-light W fluorescent tube. The aqueous solution containing dichlorvos was continuously pumped through the photoreactor. Several factors, such as the initial dichlorvos concentration, dissolved oxygen, electrolytes, flow rate and temperature, affecting the oxidation rate of dichlorvos were studied. The results indicate that photocatalysis can be an effective process for the degradation of dichlorvos. The activated energy for the photocatalytic degradation of dichlorvos is 28.4 kJ mol(-1). The initial quantum yield for the destruction of dichlorvos is 2.67%. Increasing the flow rate and initial dichlorvos concentration increases the dichlorvos degradation rate. Total mineralization requires a much longer illumination time than the disappearance of dichlorvos. Phosphate-containing intermediates are more stable than chloride-containing intermediates. It is shown that the photocatalytic oxidation of dichlorvos follows the Langmuir-Hinshelwood-type behavior, and reaction byproducts display an inhibiting effect on degradation rate.
MICROTOX BIOASSAY OF PHOTODEGRADATION PRODUCTS FROM PHOTOCATALYTIC OXIDATION OF PESTICIDES
(1993-11-01)
LU, MC
;
ROAM, GD
;
CHEN, JN
;
HUANG, CP
;
環境工程研究所
The mineralization of toxicants and the reduction of toxicity were investigated via the photocatalytic reaction. Dichlorvos (an insecticide), 2,4-D (a herbicide) and propoxur (an insecticide) were used as the model compounds in these experiments. Total organic carbon analyzer was used as a measure of mineralization of toxic compounds to assess the efficiency of photocatalytic mineralization. Microtox bioassay was employed in evaluating the toxicity of solutions treated by photocatalysis. The rate of photocatalytic mineralization is more efficient in acidic than in alkaline solution. The degradation pathway and toxicity of pesticides treated in photocatalytic process are pH dependent. Ultraviolet absorption spectra were also used for showing the different characteristics of the compounds undergoing photocatalytic mineralization.
PHOTOCATALYTIC OXIDATION OF DICHLORVOS IN THE PRESENCE OF HYDROGEN-PEROXIDE AND FERROUS ION
(1994)
LU, MC
;
ROAM, GD
;
CHEN, JN
;
HUANG, CP
;
環境工程研究所
The photocatalytic oxidation of dichlorvos has been investigated with two different reactors. The reactor using 254 nm light is a system with TiO2 suspensions. The 360 nm light is used as the light source of the fixed system which was TiO2 coated on the inner surface of the reactor. In terms of quantum yield, the 254 nm radiation is more effective for dichlorvos oxidation than the 360 nm light. The effect of H2O2 on dichlorvos oxidation shows a negative performance. The influence of H2O2 on the photocatalytic oxidation of dichlorvos is greater in the fixed system than that in the suspension system. The ferrous ions can induce the photo-Fenton-type reaction. However, the photocatalytic oxidation of dichlorvos will be inhibited slightly at the concentration of 1.0 x 10(-5) M Fe+2. This result is explained in terms of the net production of hydroxyl radical.
SEMI-SYSTOLIC ARRAY BASED MOTION ESTIMATION PROCESSOR DESIGN
(1995)
LU, MC
;
LEE, CY
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics