【摘要】：質(zhì)子耦合電子轉(zhuǎn)移反應(yīng)在生物和化學(xué)過程中普遍存在,對于PCET反應(yīng)過程的研究有助于加強我們對生物反應(yīng)中呼吸、固氮、光合作用以及人工光合作用和燃料電池等能量轉(zhuǎn)換方面的了解。因此對于PCET反應(yīng)過程的研究是非常有意義的。循環(huán)伏安等電化學(xué)方法是研究PCET反應(yīng)過程的最常用和有效手段。在稀溶液中電極表面的pH效應(yīng)引起峰形和其電位改變,甚至導(dǎo)致新峰形成。這是由于緩沖溶液不能完全中和,在PCET反應(yīng)中釋放與吸收的質(zhì)子所引起的。然而,過量的緩沖溶液會造成浪費并引入雜質(zhì)。我們利用循環(huán)伏安法研究對苯二酚,對苯醌,抗壞血酸和多巴胺在磷酸緩沖溶液中的電化學(xué)行為。在稀磷酸緩沖溶液中對苯二酚會出現(xiàn)兩對峰,增加磷酸緩沖溶液的濃度到其中的HPO42-(質(zhì)子受體)的濃度是對苯二酚的2倍的時候,對苯二酚的循環(huán)伏安峰只剩下一對寬峰。此外,當HPO42-的濃度多于對苯二酚濃度的4.5-6倍的時候。對苯二酚的電化學(xué)行為不再受磷酸緩沖溶液的影響。對苯醌在磷酸緩沖溶液中的電化學(xué)行為取決于H2PO4-(質(zhì)子供體)的濃度,得到的結(jié)果與對苯二酚的結(jié)果相似。多巴胺在被電化學(xué)氧化之后,發(fā)生環(huán)化反應(yīng)釋放更多的質(zhì)子。因此,在其反應(yīng)過程中需要更多的緩沖溶液。我們的結(jié)果為電化學(xué)研究PCET反應(yīng)中需要的適宜量的緩沖溶液提供了一個基本的指導(dǎo)。本文中我們利用以上原理進行實驗,我們的結(jié)果為抑制電化學(xué)研究PCET反應(yīng)中的pH效應(yīng)所需要的適宜量的緩沖溶液提供了一個基本的指導(dǎo)。土壤堿化本來是一個緩慢的過程,然而由于近年來工業(yè)高速發(fā)展和人類農(nóng)業(yè)生產(chǎn)活動,使環(huán)境與生態(tài)受到不良影響而加速了土壤的堿化過程,土壤堿化使土壤穩(wěn)態(tài)系統(tǒng)與酸堿平衡被打破,導(dǎo)致土壤中營養(yǎng)元素缺乏,農(nóng)作物減產(chǎn),因此預(yù)防和監(jiān)測土壤堿化成了關(guān)鍵問題,緩沖容量可以反應(yīng)土壤系統(tǒng)的整體狀態(tài),通過檢測土壤緩沖容量可以監(jiān)測土壤堿化問題,而傳統(tǒng)的檢測緩沖容量的方法復(fù)雜且周期長,因此需要尋找一個方便快捷的方法,在本文中我們利用電化學(xué)方法檢測堿性土壤的緩沖能力,這種方法無需加入酸,也無需達到酸堿平衡,檢測速度快,靈敏度高,是比較有實際應(yīng)用意義的一種測定土壤緩沖能力的新方法。為平衡土壤酸堿性,保持土壤肥力提供依據(jù)。
[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.
【學(xué)位授予單位】：遼寧大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：O646

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