铱基pH 电极的构建及其在浑浊水体监测中的应用
周正文
学位类型硕士
导师潘大为
2021-05
培养单位中国科学院烟台海岸带研究所
学位授予单位中国科学院大学
学位授予地点中国科学院烟台海岸带研究所
学位名称工程硕士
学位专业环境工程
关键词铱基电极浑浊水体pH 监测河口海岸带Iridium based electrodeTurbid waterpH monitoringEstuarineCoastal zone
摘要浑浊水体，一般是指水体浊度值在10 NTU以上或者悬浮颗粒物浓度（SPM）10 g/L 以上的水体。pH 值作为环境监测的必要参数之一，与河口海岸带环境的发展和变迁密切相关。但在河口海岸带区域，河水和海水发生剧烈交换，造成水体再悬浮泥沙颗粒物增加。含泥沙等悬浮颗粒物的浑浊水体容易对传统玻璃 pH电极产生损害，并且影响 pH 光学检测中光路色散。因此，在河口海岸带的浑浊水体中进行直接、准确、稳定的 pH 值监测具有重要意义。常见的固体铱基 pH电极的制备方法有电沉积法和热氧化法等，这些方法需要昂贵的仪器设备和复杂的沉积液，限制了铱基电极的应用。因此，本论文针对 pH 监测的重要性和河口海岸带浑浊水体直接监测困难的现状，开发了新型的固体铱基 pH 电极。该电极借助氧化铱颗粒与电极基质紧密的结合能力，有效减少了泥沙悬浮颗粒物的摩擦影响，保持较长时间的稳定性和快速的响应能力，可实现浑浊水体 pH 值的快速、准确、稳定监测。本论文的工作涉及三个方面：1. 自电沉积构建铱针 pH 电极及性能测试研究本章工作通过 AB 胶将铜导线和铱丝封装组合，外露铱丝在碱性氢氧化钠溶液介质中进行循环伏安氧化还原扫描 4 圈，自电沉积制备得到尺寸为 1 cm×0.25mm 的微型铱针 pH 电极。对制备电极的表面结构、稳定性、响应斜率等进行了探究。构建的微型电极总重约为 10 g，工作电极表层氧化物膜层颗粒尺寸在50~200 nm 之间。三根铱针电极的平均线性响应为-59.67 mV/pH，接近能斯特线性响应。单根电极重复 5 次测量保持良好的重现性（RSD 2.2%）。并且在三种不同 pH 值的标准缓冲溶液中 50 s 内可达到平衡，电极最大偏差 0.1 pH。2. 高稳定性高准确度 Ir/IrO2 pH 电极构建及性能研究自电沉积的铱针电极具有良好的响应能力和快速的平衡能力，但是测试过程中电极还存在偏差大和稳定性稍差的问题。因此，本章工作致力于对先前自电沉积的铱针电极进行优化，以期提高电极的测量性能。优化了制备电极的电沉积液和电沉积圈数条件，结果表明碱性沉积液 pH 13 和电沉积 20 圈为电极制备的最佳条件。对优化制备后的 Ir/IrO2 电极的表面形貌进行扫描电子显微镜（SEM）和X 射线光电子能谱（XPS）分析，证实了表层产物为 IrO2，并对 pH 电极的制备和响应机理进行了进一步地探讨。对 Ir/IrO2 电极进行性能测试，结果显示 pH 值在 1.83~11.97 的范围内电极的平均响应斜率为-65±3.5 mV/pH。电极在三种标准缓冲的偏差分别为 0.05 pH（碱性 pH 9.18）、0.01 pH（中性 pH 6.86）和 0.02 pH（酸性 pH 4.00），测量准确度得到有效提升。实验室内对浑浊水体的测试结果显示 Ir/IrO2 pH 电极比两种传统玻璃 pH 电极更快速达到测量平衡。电极的使用寿命可达 30 d，连续测量 8 小时的漂移为 3.1 mV（0.38 mV/h）。3. 铱基 pH 电极现场监测浑浊水体 pH 值研究将上述铱基电极进行组装和整合，通过接入温度传感器和可进行程序控制的单片机，集成为一个多功能的 pH 检测器。检测器在 pH 监测过程中表现出较好的稳定性。针对黄河河口丰水期和枯水期浑浊水体分别使用检测器进行了定点和走航监测。在丰水期浊度为 750 NTU 的浑浊黄河水在线监测 1 h，水体 pH波动在 8.01~8.15 之间；在枯水期浊度值 20.6~60.5 NTU 的黄河近海口进行走航测试 3 h，浑浊水体 pH 值波动在 7.50~7.61。此外，还针对烟台市入海河流逛荡河（浊度值 16.3~53.1 NTU）水体 pH 值进行了现场检测，结果显示逛荡河河水pH 值整体波动在 7.74 至 8.00 之间。
其他摘要Turbid water generally refers to the water turbidity value of more than 10 NTU or suspended particulate matter concentration (SPM) of more than 10 g/L. As one of the necessary parameters for environmental monitoring, pH value is closely related to the development and change of estuarine and the coastal environment. However, in the estuarine and coastal zone, river water and seawater exchange violently, resulting in the increase of suspended sediment particles. The turbid water containing suspended particles such as sediment is easy to damages the traditional glass pHelectrode and affects the optical path dispersion in pH optical detection. Therefore, direct, accurate, and stable pH monitoring is of great significance in estuarine and coastal turbid water. The common preparation methods of solid iridium-based pH electrode include electrodeposition and thermal oxidation. These methods require expensive equipment and complex deposition solution, which limits the application of iridium-based electrodes. Therefore, in view of the importance of pH monitoring and the difficulty of direct monitoring in estuarine and coastal turbid water, a new type of solid iridium-based pH electrode was developed. The electrode can effectively reduce the friction effect of suspended sediment particles by virtue of the close binding ability of iridium oxide particles and electrode matrix, maintain long-term stability and rapid response-ability, and realize rapid, accurate, and stable pH monitoring of turbid water.(1) Fabrication and characterization of iridium needle pH electrode by self-electrodeposition. In this chapter, the copper wire and iridium wire were packaged and combined by AB glue, and the exposed iridium wire was scanned by cyclic voltammetry in alkaline sodium hydroxide solution for 4 cycles. The micro iridium needle pH electrode with the size of 1 cm×0.25 mm was prepared. Thesurface structure, stability, response slope, and stability of the prepared electrode were investigated. The total weight of the microelectrode is about 10 g, and the particle size of the oxide film on the surface of the working electrode is between 50~200 nm. The average Nernst linear response of three iridium needle electrodes is -59.67 mV/pH, which is close to Nernst linear response. The relative standard deviation (RSD) was 2.2%. The maximum deviation of the electrode is about 0.1 pH. (2) Construction and performance of Ir/IrO2 pH electrode with high stability and accuracy. The self-electrodeposited iridium needle electrode has good response-ability and fast balance ability, but there are still some problems in the test process, such as large deviation and poor stability. Therefore, this chapter is devoted to optimizing the self-electrodeposited iridium needle electrode to improve the performance of the electrode. The results showed that the optimal conditions of self-electrodeposition were pH 13 and 20 cycles. Scanning electron microscopy (SEM) and X-rayphotoelectron spectroscopy (XPS) was used to analyze the surface morphology of the optimized electrode. It was confirmed that the surface product was IrO2. Furthermore, the preparation and response mechanism of self-electrodeposited iridium-based pH electrodes were discussed. The performance of the optimized iridium-based electrode was tested, and the results showed that the average response slope of the electrode was -65±3.5 mV/pH in the range of pH 1.83~11.97. The deviation of the electrode in three kinds of the standard buffer is 0.05 pH (pH 9.18), 0.01 pH (pH 6.86), and 0.02pH (pH 4.00), and the measurement accuracy was effectively improved. The measurement of turbid water in the laboratory shows that the optimized electrode can reach the measurement equilibrium faster than the two traditional glass pH electrodes. The long-term life of the electrode is up to 30 days, and the drift is 3.1 mV (0.38 mV/h) for 8 hours. (2) Construction and performance of Ir/IrO2 pH electrode with high stability and accuracy. The self-electrodeposited iridium needle electrode has good response-ability and fast balance ability, but there are still some problems in the test process, such as large deviation and poor stability. Therefore, this chapter is devoted to optimizing the self-electrodeposited iridium needle electrode to improve the performance of the electrode. The results showed that the optimal conditions of self-electrodeposition were pH 13 and 20 cycles. Scanning electron microscopy (SEM) and X-rayphotoelectron spectroscopy (XPS) was used to analyze the surface morphology of the optimized electrode. It was confirmed that the surface product was IrO2. Furthermore, the preparation and response mechanism of self-electrodeposited iridium-based pH electrodes were discussed. The performance of the optimized iridium-based electrode was tested, and the results showed that the average response slope of the electrode was -65±3.5 mV/pH in the range of pH 1.83~11.97. The deviation of the electrode in three kinds of the standard buffer is 0.05 pH (pH 9.18), 0.01 pH (pH 6.86), and 0.02pH (pH 4.00), and the measurement accuracy was effectively improved. The measurement of turbid water in the laboratory shows that the optimized electrode can reach the measurement equilibrium faster than the two traditional glass pH electrodes. The long-term life of the electrode is up to 30 days, and the drift is 3.1 mV (0.38 mV/h) for 8 hours. monitoring and navigation monitoring in the wet season and dry season respectively. In the wet season, the pH value of turbid yellow river water with a turbidity of 750 NTU fluctuates between 8.01 and 8.15 after online monitoring for 1 h; in the dry season, the pH value of turbid yellow river water near estuary with a turbidity of 20.6~60.5 NTU fluctuates between 7.50 and 7.61 after navigation test for 3 h. Besides, the pH value of the Gangdang River (turbidity value 16.3~53.1 NTU) in Yantai city was also detected. The results showed that the pH value of the Gangdang River fluctuated from 7.74 to 8.00.
页数65
语种中文
文献类型学位论文
条目标识符http://ir.yic.ac.cnhttp://ir.yic.ac.cn/handle/133337/29349
专题中科院烟台海岸带研究所知识产出

推荐引用方式
GB/T 7714周正文. 铱基pH 电极的构建及其在浑浊水体监测中的应用[D]. 中国科学院烟台海岸带研究所. 中国科学院大学,2021.


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