PCET反应电化学过程中pH效应与缓冲容量的研究及其应用

发布时间：2018-12-28 15:38

【摘要】：质子耦合电子转移反应在生物和化学过程中普遍存在,对于PCET反应过程的研究有助于加强我们对生物反应中呼吸、固氮、光合作用以及人工光合作用和燃料电池等能量转换方面的了解。因此对于PCET反应过程的研究是非常有意义的。循环伏安等电化学方法是研究PCET反应过程的最常用和有效手段。在稀溶液中电极表面的pH效应引起峰形和其电位改变,甚至导致新峰形成。这是由于缓冲溶液不能完全中和,在PCET反应中释放与吸收的质子所引起的。然而,过量的缓冲溶液会造成浪费并引入杂质。我们利用循环伏安法研究对苯二酚,对苯醌,抗坏血酸和多巴胺在磷酸缓冲溶液中的电化学行为。在稀磷酸缓冲溶液中对苯二酚会出现两对峰,增加磷酸缓冲溶液的浓度到其中的HPO42-(质子受体)的浓度是对苯二酚的2倍的时候,对苯二酚的循环伏安峰只剩下一对宽峰。此外,当HPO42-的浓度多于对苯二酚浓度的4.5-6倍的时候。对苯二酚的电化学行为不再受磷酸缓冲溶液的影响。对苯醌在磷酸缓冲溶液中的电化学行为取决于H2PO4-(质子供体)的浓度,得到的结果与对苯二酚的结果相似。多巴胺在被电化学氧化之后,发生环化反应释放更多的质子。因此,在其反应过程中需要更多的缓冲溶液。我们的结果为电化学研究PCET反应中需要的适宜量的缓冲溶液提供了一个基本的指导。本文中我们利用以上原理进行实验,我们的结果为抑制电化学研究PCET反应中的pH效应所需要的适宜量的缓冲溶液提供了一个基本的指导。土壤碱化本来是一个缓慢的过程,然而由于近年来工业高速发展和人类农业生产活动,使环境与生态受到不良影响而加速了土壤的碱化过程,土壤碱化使土壤稳态系统与酸碱平衡被打破,导致土壤中营养元素缺乏,农作物减产,因此预防和监测土壤碱化成了关键问题,缓冲容量可以反应土壤系统的整体状态,通过检测土壤缓冲容量可以监测土壤碱化问题,而传统的检测缓冲容量的方法复杂且周期长,因此需要寻找一个方便快捷的方法,在本文中我们利用电化学方法检测碱性土壤的缓冲能力,这种方法无需加入酸,也无需达到酸碱平衡,检测速度快,灵敏度高,是比较有实际应用意义的一种测定土壤缓冲能力的新方法。为平衡土壤酸碱性,保持土壤肥力提供依据。
[Abstract]:Proton coupled electron transfer reactions are widespread in biological and chemical processes, and the study of the PCET process helps to enhance our breathing and nitrogen fixation in biological reactions. Understanding of photosynthesis and energy conversion such as artificial photosynthesis and fuel cells. Therefore, the study of PCET reaction process is very meaningful. Cyclic voltammetry and other electrochemical methods are the most common and effective methods to study the process of PCET reaction. The pH effect on the electrode surface in dilute solution results in the change of peak shape and potential, and even the formation of new peak. This is due to the fact that the buffer solution can not be completely neutralized and the protons released and absorbed in the PCET reaction. However, excessive buffer solution can cause waste and introduce impurities. The electrochemical behavior of hydroquinone, p-benzoquinone, ascorbic acid and dopamine in phosphoric acid buffer solution was studied by cyclic voltammetry. In dilute phosphoric acid buffer solution, there are two peaks of hydroquinone. When the concentration of phosphoric acid buffer solution is increased to 2 times the concentration of HPO42- (proton receptor), the cyclic voltammetry of hydroquinone leaves only a wide pair of peaks. In addition, the concentration of HPO42- was 4.5-6 times higher than that of hydroquinone. The electrochemical behavior of hydroquinone is no longer affected by phosphoric acid buffer solution. The electrochemical behavior of p-benzoquinone in phosphoric acid buffer solution depends on the concentration of H _ 2PO _ 4- (proton donor), and the result is similar to that of hydroquinone. Dopamine releases more protons by cyclization after electrochemical oxidation. Therefore, more buffer solution is needed during the reaction. Our results provide a basic guidance for the electrochemical study of the appropriate amount of buffer solution in PCET reaction. In this paper, we use the above principle to carry out experiments. Our results provide a basic guidance for restraining the suitable amount of buffer solution needed for electrochemical study of pH effect in PCET reaction. Soil alkalification was originally a slow process. However, because of the rapid development of industry and human agricultural production in recent years, the environment and ecology have been adversely affected and the soil alkalization process has been accelerated. Soil alkalization breaks the balance between soil steady state and acid-base, which leads to the lack of nutrient elements in soil and the reduction of crop yield. Therefore, the prevention and monitoring of soil alkalinity becomes a key problem, and the buffer capacity can reflect the whole state of soil system. The problem of soil alkalinity can be monitored by measuring the buffer capacity of soil, but the traditional method of detecting buffer capacity is complex and has a long period, so it is necessary to find a convenient and quick method. In this paper, we use the electrochemical method to detect the buffer capacity of alkaline soil, this method does not need to add acid, nor need to achieve acid-base equilibrium, the detection speed is high, the sensitivity is high. It is a new method to measure soil buffer capacity. It provides the basis for balance of soil acidity and alkalinity and maintenance of soil fertility.
【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O646

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