电化学法检测水中硝基化合物

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题名	电化学法检测水中硝基化合物
作者	刘晨明
学位类别	博士
答辩日期	2008-06-01
授予单位	中国科学院过程工程研究所
授予地点	过程工程研究所
导师	张懿
关键词	硝基化合物硝基还原酶生物传感器电化学环境监测
其他题名	Determination of Nitro Compounds in Water by Electrochemistry Sensors
学位专业	环境工程
中文摘要	难降解有机污染物的准确、快速、在线监测一直是环境监测领域中的热点和难点，其中含硝基的化合物是一类广泛使用的化工原料，且具有较高的毒性，因此受到了广泛的关注。本文选择典型的硝基化合物硝基苯为研究对象，制备了检测水中硝基化合物的化学修饰电极和电化学生物传感器，并研发出实用化的配套集成方法。主要研究内容和结果如下： 1．研制出高活性的碳纳米管修饰电极。研究了碳纳米管的管径和管长度对其电化学性质的影响，并通过交流阻抗实验研究了影响碳纳米管修饰电极活性的因素。对于修饰电极，S型碳纳米管性能优于相同管径的L型碳纳米管，中等管径的碳纳米管对电极的催化性能改善最明显，其中采用S.MWNTs－1030型碳纳米管修饰电极，能够最大限度地提高电极对硝基苯还原的催化活性。强酸氧化处理后的碳纳米管表面含氧基团能够催化水中硝基苯的还原，是影响催化能力的主要因素，而传导电阻对催化性能影响很小。 2．建立了用于碳纳米管氧化的电化学阳极氧化法，解决了目前常用的强酸氧化法存在的污染重、能耗高等技术问题。碳纳米管在氯化钠溶液中，当阳极电位大于1.7 V（vs. SCE）的情况下能够被阳极氧化。阳极氧化法能够改变碳纳米管的形貌和化学性质，其表面含氧基团的种类和数量可以通过电氧化时间控制。等效电路模型拟合结果显示，随着氧化时间的增加，碳纳米管表面传导电阻降低，而双电层电容和法拉第电容量升高。对于电化学分析，氧化时间控制在10～30 min可获得较高活性，此时获得的碳纳米管修饰电极在定量分析中具有良好的性能，其对硝基苯的响应值最高可达强酸氧化法处理的碳纳米管响应值的15倍。 3．在碳纳米管电极上使用恒电流沉积法制备出纳米金颗粒，并直接固定在电极表面，形成纳米金－碳纳米管复合修饰电极，结合了纳米金的高催化能力和碳纳米管较大的比表面积的优点。复合修饰的线性范围很宽，在硝基苯浓度4～1000 mg/L的三个数量级内，还原峰电流与硝基苯浓度呈线性关系，检测上限超过液相色谱法的线性范围。线性相关系数0.9991，检出限为0.3 mg/L，方法准确度和精密度良好，抗干扰能力强，稳定性好，可以应用于工业废水中硝基苯的检测。 4．采用吸附、包埋、交联等多种方法在电极上修饰硝基还原酶（NR），发现在碳纳米管电极上使用吸附法修饰NR对其活性保持最为有利，添加DDAB对电子传递能够起到促进作用。NR与电极之间的结合作用结合了范德华力和共价键两种机理。使用该电极进行的电催化硝基苯还原反应为不可逆反应，电极反应的控制步骤为硝基苯在电极表面的扩散，扩散系数D＝6.26×10－7cm2/s。硝基苯在电极上还原反应的速率常数ks＝1.13×10-2 s-1。该电极在低浓度硝基苯的检测中具有良好的性能，检出限达到0.4 μg/L，NR的修饰可提高电极灵敏度29.1%。考察了pH和富集时间对检测结果的影响，并建立了NR碳纳米管修饰电极检测水中硝基苯方法。 5．建立了采用宽电位阶跃排除干扰物、窄电位阶跃检测底物的三次阶跃计时库仑法（TPSC），该方法改进了传统电位阶跃法选择性差的问题，通过控制电位阶跃方法并采用酶修饰电极提高了选择性。该方法在10 s之内可以完成任意一种组分的电化学定量分析，而目前采用的色谱法至少需要数分钟才能够完成，因此TPSC在实时检测领域有很大的优势。与循环伏安和高效液相色谱方法的分析结果使用统计方法进行比较，结果无显著性差异，TPSC方法未见系统误差，可靠性良好。 6．制备了碳纳米管丝网印刷电极，并应用于硝基苯的检测，碳纳米管的添加提高了丝网印刷电极检测硝基苯的还原峰电流30％以上。研究了印刷版面设计对于电极性能的影响，建立了丝网印刷碳纳米管电极检测水中硝基苯的方法，并考察了干扰物对印刷电极的影响。丝网印刷电极成本较低，批次一致性较好，适用于批量生产，具有广阔的实际应用前景。
英文摘要	The precise, fast and online determination of refractory organic pollutants is a hotspot and difficulty in environmental monitoring, especially the nitro compounds, which is toxicity and widely used in chemical industries. This work developed kinds of chemical modified electrodes and biosensors, and which were applied in the determination of a typical nitro compound, nitrobenzene. The main contents and results of this work are listed as follows. 1．High performance carbon nanotubes (CNTs) modified electrodes were prepared. The effect of diameter and length of CNTs to their electrochemical properties was studied. The results show that short CNTs are better than long CNTs, and the average diameter of CNTs modified electrode has the best catalytic activity. The S.MWNTs-1030 modified electrode furthest improved the nitrobenzene electrochemical reduction current. Oxidation with strong acid could add the oxygen containing groups on CNTs, improving its hydrophilicity and catalysis activity for nitrobenzene reduction. The oxygen-containing functional groups on CNTs could catalyze the reducing reaction of nitrobenzene, and the catalysis activity is affected by amount of oxygen-containing functional groups, however the resistance is not the main influence factor. 2． An electrochemical anode oxidation method was established and applied in CNTs oxidation. This method is clean, safe and controllable. In NaCl solution, CNTs could be oxidized at anode potential over 1.7 V (vs. SCE). The electrochemical oxidation method could change the appearance and surface chemical properties, and the oxygen containing groups could be controlled by anode oxidizing time. The surface resistance reduced and the surface capatance increased with the oxidizing time prolonging. The time between 10 and 30 min is a proper period for preparation a CNTs-based sensor, which has much higher response to nitrobenze than the acid oxidized CNTs. 3．Gold nanoparticles were directly deposited on CNTs modified electrode with constant current technology, the gold nanoparticles could fix on electrode firmly and a gold nanoparticles/CNTs complex modified electrode was fabricated. This electrode was used to analyze nitrobenzene in water, and the nitrobenze reduction peak current has the linear relation with nitrobenzene concentration, the linear range is 4 – 1000 mg/L of nitrobenzene, the correlation coefficient is 0.9991, the detection limit is 0.3 mg/L. The accuracy, precision, stability and anti-interference ability of this method are excellent. 4．Nitroreductase (NR) was modified on CNTs-glass carbon electrode with adsorbing, embedding and crosslinking method respectively. Among these methods, adsorbing method could preserve the enzyme activity better than other methods. The addition of DDAB could improve the electron transfer. NR and CNTs were linked with both van der waals force and covalent bond. Nitrobenzene reduction reaction on NR modified electrode is nonreversible, and the controlling step of the reaction is nitrobeneze diffusion, the diffusion coefficient D＝6.26×10－7cm2/s. The reduction reaction rate constant of nitrobenzene ks＝1.13×10-2 s-1。The NR modified is effective in low concentration nitrobenzene analysis, and the detection limit is 0.4 μg/L. The addition of NR on CNTs modified glass carbon electrode improved the sensitivity by 29.1%. The method of nitrobenzene analysis is set up, and the influencing factors for this method, such as pH and gathering time were investigated. 5．A novel electrochemical quantitative analysis method, Triple Potential Step Chronocoulometry (TPSC) was established, with a long potential step for interference elimination and a short potential step for substrate determination. TPSC improved the selectivity of potential step method with controlling the step range and using enzyme modified electrode. TPSC could analyze a component within 10 seconds, which is faster than other methods. The results from TPSC were statistically compared with that of CV and HPLC, and there is no evidence for significant difference between these methods. 6．CNTs-Screen printed electrodes were prepared and used in nitrobenzene determination. The addition of CNTs increased 30% of the nitrobenzene reduction peak current. The different designs of screen printed electrode were compared. The method of nitrobenzene analyzing method was established, and the influence of interference and pH were investigated. Screen printed electrode has the advantages of low-cost, batch consistency and adequate for batch produce, so that it has great potential in practical use.
语种	中文
公开日期	2013-09-13
页码	157
内容类型	学位论文
源URL	[http://ir.ipe.ac.cn/handle/122111/1248]
专题	过程工程研究所_研究所（批量导入）
推荐引用方式 GB/T 7714	刘晨明. 电化学法检测水中硝基化合物[D]. 过程工程研究所. 中国科学院过程工程研究所. 2008.