Study On Degradation Of Acetamiprid By UV/PS And UV/H₂O₂ In Water

Acetamiprid had been widely used because of its rapid onset and strong toxicity.It had gradually occupied a higher proportion in the market.Foranother,acetamiprid and other pesticides also caused serious pollution to water resources,In addition,due to the toxicity of acetamiprid wastewater was high and it was difficult to degrading,so the conventional treatment cannot effectively remove acetamiprid in wastewater.Two advanced oxidationmethods UV/PS and UV/H2O2 had been used to the degradation of the acetamiprid.At the same time,we verified the validity of the two methods for degradation of acetamiprid as well.We also explored the influence of various factors in water on two kinds of methods.The experimental results showed that UV/PS and UV/H2O2 can be used to remove 93.3%and 38.2%of acetamiprid in water by 30min respectively.The degradation rate of acetamiprid in water decreased from 99.9%and 68.4%to 55%and 20.4%respectively when the concentration of acetamiprid increased from O.1mmol/L to 2.5mmol/L within one hour.Degradation rate of acetamiprid increased with the concentration of oxidant improvedin some degree.Whenthe concentration of potassium persulfate increased from 0.5mmol/L to 1.5mmol/L,the degradation rate of acetamiprid increased by 43.2%.But when the oxidant concentration further increased,the degradation effect was not improved much.For UV/H2O2,when the concentration of hydrogen peroxide increased from 0.5mmol/L to 2.5mmol/L,the degradation rate of acetamiprid slowly increased by 22.8%,which did not appear to be stopped because of.the increase of oxidation dose.Acidic environment can promote the degradation of acetamiprid in UV/H2O2.When pHvalue changed,for example,when pH value was 3 and 5,the degradation rate was promoted2.2%and 9.4%respectively.Slight acidity might promote UV/PS(pH=5 degradation rate increased by 4.4%)to degrade acetarmiprid.The alkaline environment affected the degradation of acetamiprid by UV/PS(degradation rate decreased by 17.9%-29.6%)and UV/H2O2(degradation rate decreased by 18.6%-28.2%).The anion in water could cause different effects on the oxidation,the presence of chloride ions(5mmol/L and above)would reduce the UV/PS effect on acetamiprid degradation(decreased 18.8%-35%),while low concentration of.chloride ions would promote UV/H2O2 degradation of acetamiprid(5mmol/L is to promote the 9%),but when chlorine ion concentration was too high,it would reduce the degradation rate(7.1%-8.5%).Bicarbonate ion would cause the inhibition of UV/PS and UV/H2O2,when the bicarbonate concentration increased from 5mmol/L to 15mmol/L,the degree of acetamiprid's degradation rate by two kinds of oxidation decreased by 20.4%-20.8%and 7%-21.4%respectively.The presence of nitrate ions had little effect on the two reactions.There were also natural organic matter degradation of acetamiprid by UV/PS inhibition rate(degradation rate decreased by 14.4%when concentration of natural organic matter is 5mg/L),but the natural organic matter of low concentration could promote the UV/H2O2 reaction(the degradation rate was up to 9.1%),the rise of natural organic matter content(more than 10mg/L)would inhibit UV/H2O2 method(the degradation rate decreased by 1.6%).The quenching experiments verified that sulfate radical and hydroxyl radical played major roles in the UV/PS system,and in UV/H2O2 system,only the hydroxyl radicals worked.the productsof the degradation of UV/PS and UV/H2O2 were analyzed and pathways wereinferredtoo.It was found that the products of UV/PS were more than UV/H2O2,some degradation products of the two methods were deduced.In this study,the actual application of the two methods were analyzed,and the results showed that the TOC removal efficiency of two hours(49.3%)was higher than that of UV/H2O2(26.6%).However,the removal of TOC between these two methods was not very satisfactory.The economic benefit of UV/PS was better than that of UV/H2O2.This experiment also compared theeffects on different water bodies(the Yangtze River,Lake Taihu,industrial waste water),the results wasas follow:the inhibition degree of industrial effluent was very serious.