高级氧化法降解呋虫胺的研究

发布时间：2017-12-31 07:03

本文关键词：高级氧化法降解呋虫胺的研究　出处：《河南师范大学》2015年硕士论文　论文类型：学位论文

【摘要】：呋虫胺(dinotefuran),化学名称:(RS)-1-甲基-2-硝基-3-[(3-四氢呋喃)甲基]胍,是一种新型的烟碱类杀虫剂,因其具备众多优点而逐渐被人们熟知,有望成为全世界广泛使用的农药。本文分别采用4种不同的高级氧化方法降解呋虫胺,考察了呋虫胺在不同氧化方式下的降解情况,研究了不同因素对呋虫胺降解的影响,并推测其氧化降解机理。Fenton法降解呋虫胺的实验考察了不同p H条件和不同温度对呋虫胺降解的影响,结果表明:在温度一定的条件下,p H对呋虫胺降解的影响较大,当初始p H为3时最利于呋虫胺的降解,p H的升高或降低均不利于呋虫胺的降解;在初始p H一定的条件下,呋虫胺的降解率随着温度的升高而增加,但是增加幅度并不大,温度从15℃升到30℃,呋虫胺的降解率仅提高了5.38%。在温度和p H一定的条件下,通过添加不同浓度的H2O2,考察了氧化剂的量对于Fenton法降解呋虫胺的影响,结果表明当呋虫胺浓度为100 mg/L时,H2O2的最佳投加浓度为0.2 mol/L,氧化剂的浓度过高或过低均不利于呋虫胺的降解;在反应的温度、初始p H和氧化剂的量均一定的条件下,通过改变溶液中Fe2+的浓度,考察了不同浓度的催化剂对呋虫胺降解的影响,结果表明当呋虫胺的浓度为100 mg/L、H2O2的投加浓度为0.2 mol/L时,Fe2+的最佳浓度为0.06 mmol/L。对呋虫胺在不同条件下的降解情况进行动力学拟合分析,可知Fenton法降解呋虫胺的反应符合二级动力学规律。通过高效液相色谱和质谱联用技术(HPLC-MS)对产物进行分离鉴定,可知呋虫胺只有一种降解产物,可能为1-甲基-3-(四氢-3-呋喃甲基)脲。Fenton法联合光照降解呋虫胺的实验考察了温度、p H、氧化剂的量及催化剂的量等因素对呋虫胺降解的影响,鉴于目前实际工程中的废水处理大多以COD为检测标准,故本节实验以COD的降解率为指标。实验结果表明,当呋虫胺的初始浓度为200 mg/L时,光照联合Fenton降解呋虫胺的最佳条件为:温度30℃,p H为3.0,Fe2+浓度为0.2mmol/L,H2O2的浓度为32 mmol/L。H2O2投加方式也对Fenton法降解呋虫胺的过程有影响,实验结果表明当总投加量一定时,采用分批次投加且先多量后少量的投加方式更利于COD的降解。超声联合Fenton法考察了不同频率的超声波对COD降解的影响,结果表明低频率超声促进COD的降解,高频率超声反而抑制COD的降解。热活化过硫酸钾降解呋虫胺的实验结果表明,温度越高,呋虫胺的降解速率越快,通过对呋虫胺降解的情况进行动力学拟合分析,发现热活化过硫酸钾降解呋虫胺的过程符合一级动力学规律,当温度为40、50、60、70、80℃时,呋虫胺降解的半衰期分别为1732、990、173、22、7 min,通过阿伦尼乌斯方程得过硫酸钾降解呋虫胺的活化能为133.498 k J/mol。通过调节不同的初始p H,可知p H对过硫酸钾降解呋虫胺的影响较小,中性条件下可达最高降解率仅比碱性条件下达到的最低降解率高了6.05%。过硫酸钾的浓度对于呋虫胺的降解影响较大,在温度一定时(70℃),过硫酸钾浓度为2、4、6、8、10、25、50 mmol/L,呋虫胺的降解半衰期分别为173、90、77、45、28、9、6 min。Cl-和HCO3-对反应的影响较为复杂,当溶液中的Cl-浓度和HCO3-浓度较低时,均能够促进呋虫胺的降解,当其浓度超过某拐点浓度时呋虫胺的降解则逐渐受到抑制。超声的存在能够明显促进呋虫胺的降解。通过添加自由基捕获剂探究其降解机理,结果表明,该反应体系中同时存在着硫酸根自由基·SO4-和羟基自由基·OH,两种自由基均参与了呋虫胺的降解,且起主要作用的为·SO4-。
[Abstract]:Dinotefuran (dinotefuran), chemical name: (RS) -1- methyl -2- nitro -3-[(3- tetrahydrofuran) methyl] guanidine, is a new type of neonicotinoid insecticides, because it has many advantages and have been gradually known, is expected to become widely used pesticides in the world. This paper uses 4 kinds of advanced oxidation method different degradation dinotefuran, investigated the degradation of dinotefuran in different oxidation conditions, the effects of different factors on the degradation of dinotefuran, and speculated that the degradation mechanism of.Fenton degradation by dinotefuran studied P H, different conditions and different temperature on the degradation of dinotefuran the results show that under certain temperature condition, effect of P H on dinotefuran degradation is larger, the initial P H 3 the degradation most beneficial to dinotefuran, degradation of P H increased or decreased was not conducive to dinotefuran; in the initial P H, degradation of furosemide worm amine The rate increases with the increase of temperature, but the increase is not large, the temperature from 15 DEG C to 30 DEG C, the degradation rate of only dinotefuran increased 5.38%. in temperature and P H under certain conditions by adding different concentrations of H2O2, the effects of the amount of oxidant for Fenton degradation of dinotefuran the results show that when the dinotefuran concentration was 100 mg/L, H2O2 dosage was 0.2 mol/L and the concentration of oxidant concentration was too high or too low is not conducive to the degradation of dinotefuran; in the reaction temperature, the initial P H and oxidant amount under certain conditions by changing the concentration of solution in Fe2+, we investigated the effect of different concentration of dinotefuran degradation, the results showed that when the dinotefuran was 100 mg/L, H2O2 dosage is 0.2 mol/L, the optimal concentration of Fe2+ was 0.06 mmol/L. for the kinetics of degradation of dinotefuran under different conditions Analysis shows that Fenton degradation of dinotefuran reaction with two order kinetics. By high performance liquid chromatography and mass spectrometry (HPLC-MS) and the products were separated and identified, the dinotefuran is only one possible degradation products, 1- methyl -3- (four h -3- methylfuran) urea.Fenton method combined with light the degradation of dinotefuran experiments the effects of temperature, P H, factors affecting the amount of oxidant and catalyst amount on dinotefuran degradation, in view of the current wastewater treatment engineering are based on COD standards, and therefore the experiment with the degradation rate of COD as index. The experimental results show that when the initial the concentration of dinotefuran was 200 mg/L, the best light conditions combined with Fenton degradation dinotefuran: temperature 30, P H 3, Fe2+ concentration is 0.2mmol/L, the concentration of H2O2 was affected 32 mmol/L.H2O2 dosing mode also process of Fenton degradation by dinotefuran, experiments. Results show that when the total dosage when using batches and the first volume and degradation of investment after a small amount of adding more favorable COD. Ultrasound combined with Fenton to investigate the effect of different frequency ultrasonic on COD degradation. The results show that the degradation of low frequency ultrasound to promote the COD degradation of high frequency ultrasonic inhibited COD. The activation of potassium persulfate degradation dinotefuran. The experimental results show that the higher the temperature, the degradation rate of dinotefuran faster, the dynamic fitting through the analysis of the dinotefuran degradation, found that the thermal activation process of potassium sulfate degradation dinotefuran accord with first-order kinetics when the temperature 40,50,60,70,80 C, dinotefuran degradation half-life of 1732990173,22,7 min respectively, through the Arrhenius equation to activation of potassium sulfate degradation dinotefuran to 133.498 K J/mol. by adjusting the different initial P H, P H of persulfate The smaller effect of potassium degradation dinotefuran, minimum degradation under neutral conditions can reach the highest degradation rate than under alkaline conditions reached the rate of high concentration of 6.05%. potassium persulfate for degradation of dinotefuran influence, in a certain temperature (70 DEG C), potassium persulfate concentration was 2,4,6,8,10,25,50 mmol/L, the degradation half-life of furosemide. Amine were unaffected by 173,90,77,45,28,9,6 min.Cl- and HCO3- on the reaction is more complex, when the concentration of Cl- and HCO3- concentration in the solution is low, can promote the degradation of dinotefuran, when the concentration exceeds a certain inflection point when the concentration of degradation dinotefuran is gradually suppressed. The presence of ultrasound can significantly promote the degradation of furosemide. Amine. By adding free radical scavenger on the degradation mechanism, the results show that the exist of the reaction system with sulfate radical and hydroxyl radical - SO4- - OH, two free radicals are involved in the dinotefuran Degradation, and the main effect is. SO4-.

【学位授予单位】：河南师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X592

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