乙酰甲胺磷农药的纳米TiO2光催化降解特性研究

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3.0 陈辉 2024-11-19 6 4 2.15MB 97 页 15积分

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摘要

本研究以乙酰甲胺磷为底物，首先对磷钼蓝分光光度法测定有机磷农药残留

量这种方法进行了改进。在此基础上，对降解过程中的内外界影响因素进行了探

讨，并通过响应曲面试验及反应动力学研究，给出了总体的最优控制条件。主要

研究结果如下：

对磷钼蓝分光光度测定法进行了改进。当检测波长为 890nm；反应体系为

2.0mL 钼酸铵溶液(26g/L)、1.0mL 抗坏血酸溶液(100g/L)并添加 0.4g/L EDTA；45℃

水浴条件下显色 10min。在此条件下，测定吸光度与质量呈线性关系，PO43-的量

在0～160μg 范围内符合比耳定律，磷酸盐测定回归方程为 Y=0.00453X-0.00229，

相关系数(R2)=0.99984，表观摩尔吸光系数为 2.118×104L/(mol·cm)，方法回收率为

95.199%～102.097%。此方法操作简单，可满足有机磷农药残留量的检测要求。

光催化降解反应器的合理优化对于提高有机磷农药的光催化降解效率有重要

作用。以石英材质加工冷阱部分、钠钙玻璃加工外层反应瓶的内照式反应器配以

450W、主波长 365nm 的高压汞灯搭建的反应平台，经评估，反应 60min 可使乙酰

甲胺磷农药降解率达 96.55%。

本文研究了 UV-纳米 TiO2光催化降解乙酰甲胺磷的可行性，当添加 0.1g/L 的

纳米 TiO2(德国 P25)，乙酰甲胺磷的起始浓度为 20mg/L，温度控制在 25℃，调节反

应体系的 pH 为11 时，以高压汞灯持续照射 80min 即可实现对乙酰甲胺磷 99.9%

的光催化降解。在此基础上进一步探讨外界条件的影响，结果表明，氧气比例相

对较高的反应气体比例、添加 H2O2、Fe3+、Cu2+能促进乙酰甲胺磷的光催化降解；

而乙醇、丙酮的添加不利于乙酰甲胺磷的光催化降解。在前期确定的乙酰甲胺磷

的UV-纳米 TiO2反应体系中，当反应体系中的氧气比例达 80%时，添加 0.2mmol/L

的Cu2+和10mmol/L 的H2O2时，仅反应 20min 后，乙酰甲胺磷的光催化降解率即

可达 98.03%。

利用响应面法对影响光催化降解乙酰甲胺磷农药的关键性因子及交互作用分

析结果表明，光催化氧化法处理对影响值降解率均有较为显著的影响，适宜的控

制条件为：半导体催化剂纳米 TiO2的用量为 0.1g/L，H2O2:Cu2+添加比例为 26.34，

乙酰甲胺磷农药的初始浓度为 23.09 mg/L，降解时间为 25.42min 时，在此条件下，

光催化降解乙酰甲胺磷农药的理论值可达 100.414％，其验证试验中的测定值为

99.99%，此模型可满足推测光催化降解乙酰甲胺磷的要求。

光催化降解乙酰甲胺磷符合 Langmuir-Hinshwood 动力学规律。即随底物浓度

减少，反应级数的变化为由零级反应逐渐过渡到一级反应。就催化剂用量、温度、

初始 pH、反应体系中气体比例对 20 mg/L 乙酰甲胺磷光催化降解过程的影响而言，

均符合零级反应动力学；添加 H2O2及Cu2+对20 mg/L 乙酰甲胺磷光催化降解过程

的影响较符合一级反应动力学方程。

关键词：磷钼蓝分光光度法乙酰甲胺磷改进光催化反应器降解影响因素纳

米TiO2响应曲面反应动力学

ABSTRACT

In order to improve the degradation rate of acephate, an organophosphorus

pesticide, based on the improvement of photocatalytic degradation reactor and the

spectrophotometric determination method of organic phosphorus pesticide by

phospho-molybdenum blue. The effects of factors, such as radiation mode and duration,

TiO2type and concentration, initial acephate concentration, temperature, initial pH

value, H2O2, metal ions and gas ratio on the photodegradation efficiency have been

systematically examined. Furthermore, optimization of the process has been conducted

through the Response Surface Methodology (RSM) and Reaction-Dynamics analysis.

The main research results were as following:

The improvement of spectrophotometric determination of organic phosphorus

pesticide by phospho-molybdenum blue was studied. The results indicated that when the

detection wavelength was chosen as 890 nm, adding 2.00 mL ammonium molybdate

solution (26 g/L), and 1.00 mL ascorbic acid (100g/L , containing 0.4 g/L EDTA), and

incubated at 45℃for 10min, a good linear relationship between absorbance (A) and

phosphate mass (μg) was observed, which could be expressed as Y=0.00453X-0.00229

(R2= 0.99984),and the apparent molar absorptivity is 2.118×104L/(mol·cm).The mass

concentration of PO43- is 0-160 μg and conforms to Beer’s law.Mean recoveries of

phosphate varied from 95.199% to 102.097%.The method has the merits of easy

operation, and therefore is applicable to the requirements of organophosphorus pesticide

residues detection.

Improvement of photocatalytic degradation reactor plays an important role in the

oxidation of organic phosphorus pesticide. Utilized the degradation of acephate as an

object, we fistly discussed about illuminant species, reactor material, reactor structure,

and the way to combine illuminator with the reactor, experiments have also been

conducted to find out the optimal conditions for the design of photocatalytic

degradation reactor. Besides, the new reactors have been build with quartz cryotrapping

part, sodium calcium glass outer reactior and 450W, 365 nm high-pressure mercury

lamp. The evaluation suggested that photocatalysis of acephate pesticide for 60min was

96.55%.

The effects of radiation mode and duration, TiO2type and concentration, initial

acephate concentration, temperature and initial pH value on the photodegradation

efficiency have been examined. The photocatalytic effect was more efficient when the

initial acephate concentration was 20 mg/L and in a suspension containing 0.1 g/L

Degussa P25 TiO2, while keeping the reaction solution at 25 ℃and continuously

irradiated for 80min was found to be favorable for the degradation. It seems that an

alkaline solution (pH=11) could improve the photodegradation efficiency of acephate.

The addition of gas with higher oxygen ratio, H2O2, Fe3+ or Cu2+ would be favorable for

the degradation, while the addition of ethanol or acetone would hinder the process.

Accordingly, a degradation of more than 98.03% of acephate would be achieved when

adding 0.2mmol/L Cu2+, 10mmol/L H2O2to the optimal operational conditions after 20

min irradiation, provided the oxygen ratio is 80%.

Response surface methodology (RSM) was utilized to explore the main factors

influencing UV-TiO2photocatalytic degradation of acephate. A quadratic curved

surface model was obtained using Design-Expert software. When the initial acephate

concentration was 23.09mg/L and in a suspension containing 0.1 g/L P25 TiO2, while

keeping the H2O2:Cu2+ ratio at 26.34:1, a degradation of more than 99.99% of acephate

would be achieved after 25.42 min irradiation The regression analysis showed that the

model was highly coincided with the experimental results(R2=0.9996).

The kinetics of the photocatalytic degradation of acephate could be well described

by Langmuir-Hinshwood model. The photocatalytic degradation rate of acephate

follows the first-order reaction kinetics under lower initial concentration conditions,

while under higher initial concentration, the degradationwould confirm to zero-order

reaction. At the same time, the kinetics of reaction are significantly influenced by the

catalyst amount, temperature, pH, air condition intensity, and the addition of H2O2and

Cu2+ obviously, which would follow the first-order reaction kinetics.

Key Word：

Phosphp-molybdenum blue, Spectrophotometry, Acephate,

improvement, Photocatalytic degradation, Reactor, Degradation,

Influencing factor, Nanometer TiO2, Response surface methodology

(RSM), Reaction-dynamics research

摘要

ABSTRACT

第一章绪论.................................................................................................................1

§1.1 有机磷农药的概述 ............................................................................................. 1

§1.1.1 有机磷农药在农药体系的地位...................................................................1

§1.1.2 有机磷农药的分类.......................................................................................1

§1.1.3 有机磷农药残留与食品安全现状...............................................................3

§1.2 光催化氧化处理有机污染物的基本原理 ......................................................... 3

§1.2.1 光催化氧化还原机理...................................................................................4

§1.2.2 光催化反应的动力学研究...........................................................................6

§1.3 影响光催化反应活性的因素 ............................................................................. 8

§1.3.1 光催化反应器的构成...................................................................................8

§1.3.2 催化剂.........................................................................................................13

§1.3.3 有机磷农药的初始浓度.............................................................................15

§1.3.4 反应温度.....................................................................................................15

§1.3.5 溶液 pH 值..................................................................................................16

§1.4 影响光催化反应活性的辅助因素及优化 ....................................................... 16

§1.4.1 通入气体对降解过程的影响.....................................................................16

§1.4.2 添加氧化剂对降解过程的影响.................................................................17

§1.4.3 添加金属离子对降解过程的影响.............................................................17

§1.4.4 光化学降解过程中光敏(猝灭)剂作用研究.............................................. 17

§1.5 课题研究意义及主要内容 ............................................................................... 17

§1.5.1 课题研究意义.............................................................................................17

§1.5.2 课题主要研究内容.....................................................................................18

第二章磷钼蓝分光光度法测定有机磷农药残留量的改进.....................................19

§2.1 引言 ................................................................................................................... 19

§2.2 材料与方法 ....................................................................................................... 19

§2.2.1 材料与仪器.................................................................................................19

§2.2.2 试验方法.....................................................................................................20

§2.2.3 数据分析处理.............................................................................................21

§2.3 结果与分析 ....................................................................................................... 22

§2.3.1 检测波长的选择.........................................................................................22

§2.3.2 还原剂体系的优化.....................................................................................22

§2.3.3 显色体系酸度的确定.................................................................................23

§2.3.4 反应温度及时间对显色液稳定性的影响.................................................24

§2.3.5 共存离子的影响.........................................................................................25

§2.3.6 精密度和加标回收率试验.........................................................................26

§2.3.7 线性范围及方法的灵敏度试验.................................................................26

§2.4 本章小结 ........................................................................................................... 27

第三章适用于有机磷农残降解的纳米 TiO2光催化反应器关键性能参数研究 ... 28

§3.1 引言 ................................................................................................................... 28

§3.2 材料与方法 ....................................................................................................... 29

§3.2.1 材料与仪器.................................................................................................29

§3.2.2 测定方法.....................................................................................................30

§3.2.3 试验方法.....................................................................................................31

§3.2.4 数据分析处理.............................................................................................31

§3.3 结果与分析 ....................................................................................................... 32

§3.3.1 光源对光催化反应器降解效果的影响.....................................................32

§3.3.2 反应器结构对光催化反应器降解效果的影响.........................................33

§3.3.3 应器的材质对光催化反应器降解效果的影响.........................................34

§3.4 本章小结 ........................................................................................................... 35

第四章乙酰甲胺磷 UV-纳米 TiO2光催化降解影响因素的研究........................... 37

§4.1 引言 ................................................................................................................... 37

§4.2 材料与方法 ....................................................................................................... 37

§4.2.1 材料与仪器.................................................................................................37

§4.2.2 试验方法.....................................................................................................38

§4.2.3 数据分析处理.............................................................................................40

§4.3 结果与分析 ....................................................................................................... 40

§4.3.1 单纯光解或氧化作用对乙酰甲胺磷的降解作用.....................................40

§4.3.2 高压汞灯照射时间及方式对乙酰甲胺磷降解效果的影响.....................40

§4.3.3 催化剂种类选择及用量对降解效果的影响.............................................41

§4.3.4 乙酰甲胺磷初始浓度对降解效果的影响.................................................43

§4.3.5 温度对对乙酰甲胺磷降解效果的影响.....................................................44

§4.3.6 pH 值对乙酰甲胺磷降解效果的影响.......................................................45

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摘要：

摘要本研究以乙酰甲胺磷为底物，首先对磷钼蓝分光光度法测定有机磷农药残留量这种方法进行了改进。在此基础上，对降解过程中的内外界影响因素进行了探讨，并通过响应曲面试验及反应动力学研究，给出了总体的最优控制条件。主要研究结果如下：对磷钼蓝分光光度测定法进行了改进。当检测波长为890nm；反应体系为2.0mL钼酸铵溶液(26g/L)、1.0mL抗坏血酸溶液(100g/L)并添加0.4g/LEDTA；45℃水浴条件下显色10min。在此条件下，测定吸光度与质量呈线性关系，PO43-的量在0～160μg范围内符合比耳定律，磷酸盐测定回归方程为Y=0.00453X-0.00229，相关系数(R2)=0.99...

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