离子选择膜技术及其土壤硝态氮检测应用研究

发布时间：2018-04-25 13:16

  本文选题：离子选择膜技术 + 全固态离子选择电极　； 参考：《中国农业大学》2016年博士论文

【摘要】：化肥是重要的农业生产资料对粮食增产起到不可替代的作用。近年来,因盲目追求高产、稳产而导致的化肥尤其氮肥的过量施用造成了严重的农业面源污染和经济效益下降。研究符合国情的土壤硝态氮前端感知技术,为测土施肥提供技术保障具有重要意义。基于聚合物敏感膜电极的硝态氮测量研究日益受到学界重视,通过国际合作攻关机制,研究课题组在全固态硝酸根掺杂聚吡咯膜电极的研究方面取得了阶段性突破但电极的稳定性及抗干扰性问题成为了电极数据解译与实际应用的瓶颈。本文以离子选择性敏感膜表面微形貌调控为切入点,系统开展微形貌特征提取、量化、调控等制备技术研究,揭示离子敏感膜微形貌与其土壤硝态氮检测性能间的作用机理及模型,进一步加深了对聚合物选择性敏感膜的响应机理及过程的理解,对拓展基于全固态聚合膜电极的硝态氮快速低成本检测技术研究具有重要的学术价值和现实意义。具体研究工作包括：1、研究了硝酸根掺杂聚吡咯膜的分形特征,探讨了分形特征与传感器性能之间的关系。通过改变聚合电流密度,在玻碳基底(GC)上制备不同形貌特征的NO3掺杂聚吡咯膜(PPy-NO3-),对膜进行分形分析,探讨了分形维数与电极电化学、传质动力学性能的关系。研究结果表明：PPy-NO3膜具有分形特性,改变聚合电流密度能够明显改变膜的形貌；分形维数(Df)能更准确地表征膜的微观综合复杂程度;在一定范围内分形维数与电极的线性范围、响应速率、检测下限性能具有正相关关系,分形维数越大离子的膜相扩散系数越高：1.2mA·cm-2聚合电流下膜的Df=2.58、扩散系数D=7.48×10-11 crn2·s-1,相应电极的线性范围5.0×10-5-1.0×10-1M、响应斜率-53.3mV·decade-1、响应时间60 s,对主要干扰离子的选择系数均达到10-2数量级。2、解析了水层形成导致响应电势漂移的机理,研制了以PPy-NO3-和石墨烯(GR)复合材料(PPy-NO3-/GR)为离子敏感膜的全固态离子选择电极,有效抑制了电势漂移。采用电化学还原法在GC表面直接修饰GR层,通过脉冲聚合法实现PPy-NO3-膜的聚合及与GR的复合并制备传感器。研究结果表明：所制备的传感器具备良好的电化学分析性能,包括：响应斜率为-56.2mV·decade-1、线性范围为10-5-1.0×10-1M、检测下限为0.63×10-5M、响应时间15 s及logKNO3-,Cl-=-2.5。响应电势稳定性得到较大提升,ΔE·△t-1达到了0.67±0.05 mV·h-1。实际土样测量结果显示,该传感器具有较高的准确性且能在土壤泥浆直测方式下保持较好的稳定性。3、理论解析了膜极化对电极响应电势稳定性的影响,提出了抑制极化的微结构调整方向,制备了具有纳米管状微形貌结构的PPy-NO3--(T)膜,构建了相应的PPy-NO3-- (T) /GR/GC全固态离子选择电极。利用直链淀粉分子模板诱导吡咯单体定向聚合生长,实现了纳米管状聚吡咯微结构可控制备。实验结果表明：所制备的纳米管状微结构能极大提高了离子敏感膜的离子传输速率,Rct到了95.7Ω,电化学电容Cem达到了0.98 mF、Cdl达到了4.5×10-6 mF,所制备的电极具备较高的稳定性,ΔE·△t-1达到了80±6 μV·h-1。4、建立了适用于PPy-NO3-(T)/GR/GC电极在高浓度干扰离子存在、大范围温度变化情况下的干扰校正ANN模型。模型的输入为氯电极、PPy-NO3--(T)/GR/GC电极的响应电动势和测试温度,输出为NO3--N浓度,利用响应面法解析模型参数及其交互作用对模型预测能力的影响并优化计算相应参数值。研究结果表明：ANN拓扑3-8-1、动量系数0.73、学习率0.33所对应的模型具有较好的预测能力(RMSET=2.75mg·kg-1, R2=0.97),对高Cl-干扰情况下的校正效果要优于传统能斯特方程标定法,其有望用于农田土壤硝态氮的实际测试。
[Abstract]:Chemical fertilizer is an important agricultural production material which plays an irreplaceable role in increasing grain yield. In recent years, the excessive application of chemical fertilizer, especially nitrogen fertilizer, caused by blind pursuit of high yield and stable yield, has caused serious agricultural non-point source pollution and economic benefit decline. The study on the measurement of nitrate nitrogen based on the polymer sensitive membrane electrode has attracted more and more attention. Through the international cooperation mechanism, the research group has made a breakthrough in the research of all solid state nitrate doped polypyrrole membrane electrode, but the electrode stability and anti-interference problems have become the number of electrodes. According to the bottleneck of the interpretation and practical application, this paper takes the surface micromorphology of the ion selective sensitive membrane as the breakthrough point, and studies the preparation technology of the micro morphology feature extraction, quantification and regulation, and reveals the mechanism and model of the micromorphology of the ion sensitive membrane and the detection performance of soil nitrate nitrogen, and further deepens the selection of the polymer. The understanding of the response mechanism and process of the sensitive membrane is of great academic and practical significance for expanding the rapid and low cost detection technology of nitrate nitrogen based on all solid state polymeric membrane electrodes. The specific research work includes: 1, the fractal characteristics of the nitrate doped polypyrrole film are studied, and the fractal characteristics are discussed between the properties of the sensor and the performance of the sensor. By changing the polymerization current density, the NO3 doped polypyrrole film (PPy-NO3-) with different morphologies was prepared on the glass carbon substrate (GC). The fractal analysis of the membrane was carried out. The relationship between the fractal dimension and the electrode electrochemistry and the mass transfer kinetics was discussed. The results show that the PPy-NO3 film has the fractal characteristics and the polymerization current density can be changed. The morphology of the membrane is obviously changed, and the fractal dimension (Df) can more accurately characterize the micro comprehensive complexity of the membrane. In a certain range, the fractal dimension has a positive correlation with the linear range of the electrode, the response rate and the lower limit performance. The larger the fractal dimension is, the higher the membrane diffusion coefficient of the ions is: the Df=2.58 of the film under the polymerization current of 1.2mA. Cm-2. The diffusion coefficient is D=7.48 x 10-11 crn2. S-1, the linear range of the corresponding electrode is 5 x 10-5-1.0 x 10-1M, the response slope -53.3mV decade-1 and the response time 60 s, the selection coefficients of the main interfering ions are all 10-2 orders of magnitude.2, and the mechanism of the water layer formation in response to the drift of the response potential is analyzed, and the PPy-NO3- and the GR (PPy) composite material (PPy) is developed. -NO3-/GR) is an all solid ion selective electrode for the ion sensitive membrane, which effectively inhibits the drift of the potential. The electrochemical reduction method is used to modify the GR layer on the surface of the GC directly. The polymerization of the PPy-NO3- film and the composite of the GR with the GR are realized by the pulse polymerization. The results show that the prepared sensor has good electrochemical analysis. The results are as follows: the response slope is -56.2mV decade-1, the linear range is 10-5-1.0 x 10-1M, the detection limit is 0.63 x 10-5M, the response time is 15 s and logKNO3-, the Cl-=-2.5. response potential stability is greatly improved. The delta E / delta T-1 reaches 0.67 + 0.05 mV. The actual soil sample measurement of the h-1. is high accuracy and can be in the soil. A good stability.3 was maintained under the direct measurement of soil mud. The effect of membrane polarization on the stability of electrode response potential was theoretically analyzed. The direction of microstructural adjustment was proposed. The PPy-NO3-- (T) membrane with nanotubular micromorphology was prepared, and a corresponding PPy-NO3-- (T) /GR/GC all solid state ion selective electrode was constructed. The amylose molecular template induced the directional polymerization of pyrrole monomer and realized the controlled preparation of the nanotubular polypyrrole microstructure. The experimental results show that the nano tubular microstructures can greatly improve the ion transmission rate of the ion sensitive membrane, Rct to 95.7 Omega, the electrochemical capacitance of Cem reached 0.98 mF, and the Cdl reached 4.5 * 10-6 mF. The prepared electrode has high stability, and the delta E. Delta T-1 reaches 80 + 6 V. H-1.4. The interference correction ANN model is established for the PPy-NO3- (T) /GR/GC electrode under the presence of high concentration interfering ions and large range of temperature changes. The input of the model is the chlorine electrode, the PPy-NO3-- (T) /GR/GC electrode is the response electromotive force and the test temperature, the output is NO3--N concentration, the response surface method is used to analyze the influence of model parameters and their interaction on the model prediction ability and to optimize the calculation of the corresponding parameters. The results show that the ANN topology 3-8-1, the momentum coefficient 0.73, the learning rate 0.33 corresponding models have good prediction ability (RMSET= 2.75mg. Kg-1, R2=0.97), and the high Cl- interference condition correction. The positive effect is better than the traditional Nernst equation calibration method, which is expected to be applied to the practical test of nitrate nitrogen in farmland soil.

【学位授予单位】：中国农业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：S151.9
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本文编号：1801498