Studies On The Degradation Of Amide Hebicides In Aqueous Solution

Amide hebicides are widely used in agricultural production currently.They can be used in many crops such as corn,soybean and cotton to control annual grass weeds and some broadleaf weeds.The frequent application of amide hebicides can lead to the destruction of environment,which in turn may threaten the health of human.Therefore,the effective removal of amide hebicides in the environment is of great significance to the protection of human life safety and environment.In this thesis,photodegradation and microbial degradation of amide hebicides in aqueous solution were studied.The main results are as follows:1.The degradation of acetochlor in aqueous solution under xenon lamp(without additive,with H2O2 and with H2O2/Fe2)and mercury lamp radiation were investigated by high performance liquid chromatography(HPLC).The degradation products were compared by chromatograms.The degradation rates of acetochlor at the initial concentration of 10 mg/L were 95.33%and 95.15%under the radiation of xenon lamp for 600 min and mercury lamp for 10 min,respectively.Under xenon lamp radiation for 240 min,the degradation rates were 70.61%,84.28%and 92.61%without additive,with H2O2 and with H2O2/Fe2+,respectively.The degradation products of acetochlor without additive,with H2O2 and with H2O2/Fe2+ were different.2.The degradation of alachlor in aqueous solution under xenon lamp(without additive,with H2O2 and with H2O2/Fe2)and mercury lamp radiation were investigated by HPLC.The degradation products were compared by chromatograms.The degradation rates of alachlor at the initial concentration of 10 mg/L were 95.63%and 95.84%under the radiation of xenon lamp for 600 min and mercury lamp for 10 min,respectively.Under xenon lamp radiation for 180 min,the degradation rates were 63.89%,69.57%and 94.51%without additive,with H2O2 and with H2O2/Fe2,respectively.The degradation products of alachlor without additive,with H2O2 and with H2O2/Fe2+ were different.3.The fungal strain Penicillium sp.G3 preserved in the laboratory with a highly effective degradation ability to ?,-cyhalothrin was used to degrade acetochlor.The effects of carbon source species,additive amount of carbon source,strain inoculation,initial concentration of acetochlor,medium pH and cultivation temperature on the degradation characteristics of Penicillium sp.G3 to acetochlor were investigated by HPLC.It showed that the optimal degradation conditions of acetochlor were glucose 0.5%,strain inoculation 0.5 g/L,initial concentration 50 mg/L,pH 7 and temperature 28 ?.The degradation rate of acetochlor by Penicillium sp.G3 was 98.0707%within 3 days under the optimal degrading condition,and the half-life of degradation was 10.68 h.4.An acetochlor-degrading endophytic bacterium strain y61 was screened from the leaves of cinnamon.Based on the results of morphological characteristics,16S rRNA sequence analysis and phylogenetic tree,strain y61 was preliminarily identified as Sphingobium sp..The effects of carbon sources,strain inoculation,initial concentration of acetochlor,medium pH and cultivation temperature on the degradation characteristics of strain y61 to acetochlor were investigated by HPLC.It was found that the best degradation effect was obtained in the condition of lactose 1%,strain inoculation 5%,initial concentration 50 mg/L,pH 7 and temperature 28 ?.The strain y61 was capable of degrading up to 76.90%acetochlor within 7 days under the optimal degrading condition,and the half-life of degradation was 5.34 d.