Studies On Photodegradation Of Acetamiprid

The effects of different types of water,different light sources,pH buffer solution, nitrate and nitrite,two herbicides,H₂O₂,surfactants on the photodegradation of acetamiprid in aqueous solution were studied,the effects of adding dose of isoproturon,soil moisture on photodegradation of acetamiprid on the soil surfaces were studied.With silica gel as soil condition,we studied the photodegradation rules of acetamiprid,we also explored the photoproducts of acetamiprid in acetonitrile.1.The direct photodegradation rate of acetamiprid in aqueous solution by sunlight was slow,the half-life was 147.48h.however it quickly under HPML and UV irradiation, the half-life was 69.30 and 48.13miniutes.the photolysis follow the first order kinetics.2.In strong basic solution,acetamiprid hydrolyzed rapidly to 60.37%,46.98%in pH=9 and pH=11 within 48h at room temperamre,acetamiprid was stable in acidic solution,hydrolyzed to 99.01%within 48h at room temperature;in pure water,acetamiprid was stable.Under HPML,the pH value has significant effect on acetamiprid photolysis.The result showed the photolysis rates increased with the increase of pH value.3.The photolytic rates of acetamiprid in 4 types of water ranged as:distilled water＞Tapped water＞CHaoHu Lake water＞paddy water The half-life of acetamiprid is 69.30 min in the distiLLed water WhiLe82.50min in tapped water,103.43 min in the Chaohu Lake water and 119.48 min in the paddy water.4.The photolytic rates of acetamiprid is also affected by its concentration in laqueous solution,the higher concentration is,the lower photosis rate constant and the longer half-Lives is.In the test,with the increasing concentration of 5.0mg/L,10.0 mg/L,20.0 mg/L,Acetamiprid has half-life of 60.26min,69.30min,92.40min,respectively.5.NO₃^- and NO₂^- showed remarkable photo-quenching effects on the photodegradation of acetamiprid in water,surface.After 250min of illumination,the photo-quenching rates of NO₃^- were 7.15～16.81%,and NO₂^- were 36.35～83.43%.As the adding dose of NO₃^- increased,the photo-quenching effects of NO₃^-,NO₂^- weakened insteadly,and the half-life periods were extended to 1.04,1.08,1.01,1.35,1.12,1.27 times.6.Beta-cypermethrin,diniconazole showed remarkable photo-quenching effects on the photodegradation of acetamiprid in water,surface.After 250min of illumination,the photo-quenching rates of Beta-cypermethrin were 28.48～202.50%,and diniconazole were 186.29～471.60%. 7.Under HPML,the photolysis rates of acetamiprid were improved with H₂O₂.and the effects were stronger with the increses of H₂O₂ concentration.In the test,with the increasing concentration of 5mmol/L,10mmol/L,20mmol/L,Acetamiprid has half-life of 66.00min,63.58min,46.20min,respectively.8.The effect of three kinds of surfactants was also studied,CTAB can photosensitize the photodecomposition of acetamiprid at all the additive dosage ratio.Nongru601 and Nongru603 showed quenching effect.9.Under UV,the half life of photolysis was shortest at 10.00 mg/kg level.The photolytic rate at 5.00 mg/kg and 20.00 mg/kg levels were slower than at10.00 mg/kg level.During the photodegradation of acetamiprid on the soil surface,the photolytic rate in the prophase was obviously faster than in the anaphase.The reason was possibly related to the molecule density on the soil surface.10.The photodegradation of acetamiprid on the soil surface underUV was accelerated with the increasing of soil moisture.At 10.00 mg/kg level,the half-life period fell from21.59 h at 40%of soil moisture to 13.30h at 80%.That was mainly because the water in soil strengthens the mobility of pesticide molecule in soil.11.The photolytic rate of acetamiprid on surface of silica gel under UV is easy.The half life is only 4.015 hours,under sunlight the photodegradation of acetamipeid was very slow.The half life is about 45.89 days.Acetamiprid was stable on silica gel under dark contidion.12.Organic pigments showed remarkable photo-quenching effects on the photolysis of acetamiprid on the surface of silica gel chromatoplate.Dealing with five kinds of pigments,the half life of photolysis is extended to 1.40,1.21,1.20,1.11 and 1.06 times respectively.The order of photo-quenching effects rates is methyl red＞crystal violet＞malachite green＞riboflavin＞methylene blue.13.With silica gel as soil condition,we studied the photodegradation rules of acetamiprid.The dose of spot should be during 100-200ng.Under UV the photolytic rate of fungicide acetamiprid decreased with the increasing of dose.14.Some photolytic products of acetamiprid were identified with LC-MS and the photolytic pathway of acetamiprid in aqeous phase was also disscussed.