基于金属钼的磷酸根离子选择电极的研究与开发
发布时间：2018-11-06 20:56
【摘要】：磷作为水生物生长不可缺少的物质,在整个生物过程扮演很重要的角色。水中所含磷的浓度决定着水体质量,太高会使得藻类疯长甚至导致富营养化。随着经济的不断发展,大量未经处理的工农业污水被直接排入河水中,使得总磷浓度超过了标准含量,导致水污染甚至危害着动植物的生存。因此准确监测水中总磷浓度及时控制磷含量成为水环境保护的首要任务。离子选择电极具有选择性好、操作简单、成本效益高而且易小型化、适合实时测量等优点,并逐渐被大量用于测量磷酸盐浓度的研究。本文在敏感物质金属钼的基础上开发了一种新型电极,并用于磷的测量,主要研究成果如下:(1)研究了一种基于钼的磷酸根离子选择电极,电极测量磷酸一氢根(2-4HPO)的原理是通过钼在碱性条件下与2-4HPO反应来实现的。实验结果显示钼电极在溶液pH值为8.5条件下对磷酸氢二钠(42HPONa)在/10-10Lmol1-5-线性范围内响应斜率可以达到?/5.026.9-decm V(近能斯特Nernst斜率);检测下限达到/109.1Lmol-6?;响应时间小于50s;在连续测量中响应电位标准偏差为2mV;在不同浓度待测溶液的往复测量中电位标准偏差均小于2m V;而且除了-OH对测量有一定的影响外,钼电极对2-4HPO有很好的选择性。测量数据显示该电极至少可以使用三个月。电极制造工艺简单而且廉价,适用于水中磷酸盐的定量分析。(2)根据2-4HPO离子浓度(即磷酸盐分布系数)以及钼电极测量电位所受p H的影响,将分布系数和p H线性补偿项引入Nernst方程,建立磷酸根离子选择电极的测量模型,以克服p H对电极测量的影响。实验结果显示电极对42HPONa溶液在2-4HPO对应/10-10Lmol-1-6的线性范围内响应斜率可以达到/5.032.24-?decm V,检测下限达到/1017.1Lmol-6?,并表现出很好的线性响应特性。电极能满足磷酸盐离子的测量要求,可以用于实际水样中磷含量的在线监测。(3)针对传统总磷在线分析技术测量复杂且需要昂贵设备和使用化学试剂等缺点,研究采用实验室已有的基于3/OUV的氧化消解技术与基于钼的磷酸根离子选择电极相结合来解决,通过建立的模型优化测量效果。实验发现基于3/OUV的氧化消解技术消解后的溶液主要呈现酸性,不满足钼电极的碱性测量要求,需要采用电解自来水来调节消解溶液p H值。实验结果显示p H调节的高低对电极的测量效果有很大的影响,需要根据实际测量需求选择p H的调节值,当pH值调节整体高于7.5的情况下,电极在/109.7-1068.2Lmol-5-6??范围内达到/5.026.092-?decm V的近Nernst斜率,检测下限为/1068.2Lmol6-?;pH值调节整体低于7后,电极响应斜率降低为/0.524.622-?decm V,但线性范围变宽到/101.01-101.14Lmol-4-6??,检测下限也随之降低到/1014.1Lmol-6?。与此同时,实验发现p H调节在不同浓度下添加的电解自来水体积不同,需要依据溶液p H值来决定。
[Abstract]:Phosphorus, as an indispensable substance for the growth of aquatic organisms, plays an important role in the whole biological process. The concentration of phosphorus in the water determines the quality of the water, too high will cause algae to grow and even lead to eutrophication. With the continuous development of economy, a large number of untreated industrial and agricultural sewage is discharged directly into the river water, which makes the total phosphorus concentration exceed the standard content, leading to water pollution and even endangering the survival of animals and plants. Therefore, accurate monitoring of total phosphorus concentration in water and timely control of phosphorus content has become the primary task of water environmental protection. Ion selective electrode has many advantages such as good selectivity, simple operation, high cost benefit and easy miniaturization. It is suitable for real-time measurement and has been widely used in the study of phosphate concentration measurement. In this paper, a new type of electrode has been developed on the basis of molybdenum, which has been used in the measurement of phosphorus. The main results are as follows: (1) A kind of phosphate ion selective electrode based on molybdenum has been studied. The principle of electrode measurement of monohydrogen phosphate (2-4HPO) is achieved by the reaction of molybdenum with 2-4HPO in alkaline condition. The experimental results show that the molybdenum electrode has a slope of? / 5.026.9-decm V (near Nast Nernst slope) in the linear range of / 10-10 Lmol1-5- to sodium hydrogen phosphate (42HPONa) when the solution pH value is 8.5. The detection limit reached / 109.1 Lmol-6, the response time was less than 50 s, the standard deviation of response potential was 2 MV in continuous measurement, and the standard deviation of potential in reciprocating measurement of different concentrations of solution was less than 2m V. Besides-OH, molybdenum electrode has good selectivity to 2-4HPO. Measurements show that the electrode can be used for at least three months. The electrode manufacturing process is simple and cheap, which is suitable for quantitative analysis of phosphate in water. (2) according to the concentration of 2-4HPO ion (i.e. phosphate distribution coefficient) and the influence of pH on the potential measured by molybdenum electrode, The distribution coefficient and pH linear compensation term are introduced into Nernst equation to establish the measurement model of phosphate ion selective electrode to overcome the influence of pH on electrode measurement. The experimental results show that the response slope of the electrode to 42HPONa solution can reach / 5.032.24-?decm V in the linear range of 2-4HPO / 10-10Lmol-1-6, and the detection limit reaches / 1017.1 Lmol-6. It also shows good linear response characteristics. The electrode can meet the requirements of phosphate ion measurement and can be used for on-line monitoring of phosphorus content in real water samples. (3) in view of the disadvantages of traditional on-line total phosphorus analysis technology such as complex measurement and expensive equipment and the use of chemical reagents. In this study, the existing oxidation digestion technology based on 3/OUV and the molybdenum based phosphate ion selective electrode were used to solve the problem, and the measurement results were optimized by the established model. It was found that the solution after digestion based on 3/OUV was mainly acidic and could not meet the requirement of alkaline measurement of molybdenum electrode. Electrolytic tap water was needed to adjust pH value of digestion solution. The experimental results show that the pH regulation has a great influence on the measuring effect of the electrode. It is necessary to select the pH adjustment value according to the actual measurement demand. When the pH value is higher than 7.5, Electrode at / 109.7-1068.2 Lmol-5-6? In the range of / 5.026.092-?decm V, the near Nernst slope was reached, and the detection limit was / 1068.2 Lmol 6-buff; When the pH value is lower than 7, the electrode response slope is reduced to / 0.524.622-?decm V, but the linear range is widened to / 101.01-101.14Lmol-4-6, and the detection limit is reduced to / 1014.1 Lmol-6. At the same time, it was found that the volume of electrolytic tap water added with different concentration of pH was different, which should be determined by pH value of solution.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.1
本文编号：2315449
[Abstract]:Phosphorus, as an indispensable substance for the growth of aquatic organisms, plays an important role in the whole biological process. The concentration of phosphorus in the water determines the quality of the water, too high will cause algae to grow and even lead to eutrophication. With the continuous development of economy, a large number of untreated industrial and agricultural sewage is discharged directly into the river water, which makes the total phosphorus concentration exceed the standard content, leading to water pollution and even endangering the survival of animals and plants. Therefore, accurate monitoring of total phosphorus concentration in water and timely control of phosphorus content has become the primary task of water environmental protection. Ion selective electrode has many advantages such as good selectivity, simple operation, high cost benefit and easy miniaturization. It is suitable for real-time measurement and has been widely used in the study of phosphate concentration measurement. In this paper, a new type of electrode has been developed on the basis of molybdenum, which has been used in the measurement of phosphorus. The main results are as follows: (1) A kind of phosphate ion selective electrode based on molybdenum has been studied. The principle of electrode measurement of monohydrogen phosphate (2-4HPO) is achieved by the reaction of molybdenum with 2-4HPO in alkaline condition. The experimental results show that the molybdenum electrode has a slope of? / 5.026.9-decm V (near Nast Nernst slope) in the linear range of / 10-10 Lmol1-5- to sodium hydrogen phosphate (42HPONa) when the solution pH value is 8.5. The detection limit reached / 109.1 Lmol-6, the response time was less than 50 s, the standard deviation of response potential was 2 MV in continuous measurement, and the standard deviation of potential in reciprocating measurement of different concentrations of solution was less than 2m V. Besides-OH, molybdenum electrode has good selectivity to 2-4HPO. Measurements show that the electrode can be used for at least three months. The electrode manufacturing process is simple and cheap, which is suitable for quantitative analysis of phosphate in water. (2) according to the concentration of 2-4HPO ion (i.e. phosphate distribution coefficient) and the influence of pH on the potential measured by molybdenum electrode, The distribution coefficient and pH linear compensation term are introduced into Nernst equation to establish the measurement model of phosphate ion selective electrode to overcome the influence of pH on electrode measurement. The experimental results show that the response slope of the electrode to 42HPONa solution can reach / 5.032.24-?decm V in the linear range of 2-4HPO / 10-10Lmol-1-6, and the detection limit reaches / 1017.1 Lmol-6. It also shows good linear response characteristics. The electrode can meet the requirements of phosphate ion measurement and can be used for on-line monitoring of phosphorus content in real water samples. (3) in view of the disadvantages of traditional on-line total phosphorus analysis technology such as complex measurement and expensive equipment and the use of chemical reagents. In this study, the existing oxidation digestion technology based on 3/OUV and the molybdenum based phosphate ion selective electrode were used to solve the problem, and the measurement results were optimized by the established model. It was found that the solution after digestion based on 3/OUV was mainly acidic and could not meet the requirement of alkaline measurement of molybdenum electrode. Electrolytic tap water was needed to adjust pH value of digestion solution. The experimental results show that the pH regulation has a great influence on the measuring effect of the electrode. It is necessary to select the pH adjustment value according to the actual measurement demand. When the pH value is higher than 7.5, Electrode at / 109.7-1068.2 Lmol-5-6? In the range of / 5.026.092-?decm V, the near Nernst slope was reached, and the detection limit was / 1068.2 Lmol 6-buff; When the pH value is lower than 7, the electrode response slope is reduced to / 0.524.622-?decm V, but the linear range is widened to / 101.01-101.14Lmol-4-6, and the detection limit is reduced to / 1014.1 Lmol-6. At the same time, it was found that the volume of electrolytic tap water added with different concentration of pH was different, which should be determined by pH value of solution.
【学位授予单位】：江南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O657.1
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