發(fā)布時(shí)間：2018-06-02 19:10

  本文選題：硝酸鹽 + 電化學(xué)還原��； 參考：《中國(guó)地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：地下水是世界各國(guó)重要而又寶貴的資源,在人類生產(chǎn)生活中扮演著至關(guān)重要的角色。隨著經(jīng)濟(jì)高速發(fā)展,過(guò)度的人類活動(dòng)引發(fā)了地下水硝酸鹽污染,成為世界所共同關(guān)注的環(huán)境問(wèn)題。地下水中硝酸鹽污染主要是由于氮肥的過(guò)度施用,還包括生活污水及工業(yè)廢水的排放、污水灌溉、固體廢棄物的淋濾下滲等。高濃度硝酸鹽的地下水對(duì)人體健康有極大的潛在危害,故去除地下水中硝酸鹽使其滿足飲用水標(biāo)準(zhǔn)顯得至關(guān)重要。電化學(xué)法去除地下水硝酸鹽因具有處理周期短、環(huán)境友好以及投資成本低等優(yōu)勢(shì)而備受關(guān)注。然而,電化學(xué)方法在目前實(shí)際應(yīng)用中存在能耗高、處理量少等問(wèn)題,使其大規(guī)模的推廣和應(yīng)用受到了限制。本研究基于電化學(xué)法還原地下水中硝酸鹽的理論,以Ti板為陰極,Ti/Ir O2-Pt為陽(yáng)極,并向電化學(xué)系統(tǒng)中加入金屬顆粒,建立雙極性金屬顆粒強(qiáng)化電化學(xué)系統(tǒng)。研究目的在于探討Na Cl投加量、電流密度以及金屬顆粒材料對(duì)金屬顆粒強(qiáng)化電化學(xué)系統(tǒng)的影響,確定強(qiáng)化系統(tǒng)的最佳運(yùn)行參數(shù);通過(guò)比較不同金屬顆粒填充方式下系統(tǒng)性能差異,揭示雙極性金屬顆粒的工作機(jī)理并驗(yàn)證其強(qiáng)化作用,深入闡述雙極性金屬顆粒強(qiáng)化電化學(xué)系統(tǒng)對(duì)地下水硝酸鹽的去除機(jī)理,為金屬顆粒強(qiáng)化電化學(xué)系統(tǒng)去除地下水中硝酸鹽的實(shí)際應(yīng)用提供理論基礎(chǔ)。結(jié)果表明,Na Cl投加量為0.5 g/L,電流密度為20 m A/cm2為雙極性金屬顆粒強(qiáng)化電化學(xué)系統(tǒng)的最佳運(yùn)行條件,Cu-Zn顆粒為該系統(tǒng)的最適填充材料。在此條件下,硝酸鹽去除率為93.94%,能量損耗為58.60 k Wh/n-NO3--N,氮?dú)膺x擇性為80.43%。同時(shí),驗(yàn)證了金屬顆粒對(duì)電化學(xué)系統(tǒng)去除硝酸鹽的強(qiáng)化作用,金屬顆粒的添加使系統(tǒng)硝酸鹽去除率提高了62.36%~78.9%,能量損耗減少3~5倍。通過(guò)比較不同金屬顆粒填充方式下的系統(tǒng)性能發(fā)現(xiàn),金屬顆粒發(fā)生極化后,形成多個(gè)微小而又獨(dú)立的電解池,在陰極半球表面發(fā)生還原反應(yīng),同時(shí)在陽(yáng)極半球表面發(fā)生氧化反應(yīng),提供更多的反應(yīng)表面,有效提高硝酸鹽的去除速率和電流利用率,降低能量損耗,對(duì)電化學(xué)系統(tǒng)起到強(qiáng)化作用。同時(shí),硝酸鹽的還原和還原副產(chǎn)物的氧化也分別發(fā)生在陰極和陽(yáng)極表面。
[Abstract]:Groundwater is an important and valuable resource in the world and plays a vital role in human production and life. With the rapid development of economy, excessive human activities have caused nitrate pollution in groundwater, which has become a common environmental problem in the world. Nitrate pollution in groundwater is mainly due to the excessive application of nitrogen fertilizer, including the discharge of domestic sewage and industrial wastewater, sewage irrigation, leaching and infiltration of solid waste, etc. The groundwater with high nitrate concentration has great potential harm to human health, so it is very important to remove nitrate from groundwater to meet the drinking water standard. Electrochemical removal of nitrate from groundwater has attracted much attention due to its advantages of short treatment period, environmental friendliness and low investment cost. However, the application of electrochemical method is limited because of its high energy consumption and low treatment capacity. Based on the theory of electrochemical reduction of nitrate in groundwater, Ti plate was used as cathode and Ti / ir O2-Pt as anode, and metal particles were added to electrochemical system to establish bipolar metal particle enhanced electrochemical system. The purpose of this study is to investigate the effects of NaCl dosage, current density and metal particle material on the electrochemical system strengthened by metal particles, and to determine the optimal operating parameters of the strengthening system. By comparing the system performance differences under different metal particle filling modes, the working mechanism of bipolar metal particles was revealed and its strengthening effect was verified, and the mechanism of nitrate removal from groundwater by electrochemical enhanced electrochemical system with bipolar metal particles was discussed in depth. It provides a theoretical basis for the practical application of metal particle enhanced electrochemical system to remove nitrate from groundwater. The results show that the best operation conditions of bipolar metal particle enhanced electrochemical system are the dosage of NaCl 0.5 g / L and the current density of 20 m A/cm2. The Cu-Zn particles are the most suitable filling materials for the system. Under these conditions, the removal rate of nitrate is 93.94 and the energy loss is 58.60k / n-NO3-N, and the selectivity of nitrogen is 80.43. At the same time, the enhancement effect of metal particles on the removal of nitrate in electrochemical system was verified. The removal rate of nitrate in the system was increased by 62.36 and 78.9, and the energy loss was reduced by 3 ~ 5 times with the addition of metal particles. By comparing the system performance of different metal particle filling methods, it is found that after the polarization of the metal particles, a number of small and independent electrolytic cells are formed and the reduction reaction takes place on the surface of the cathode hemisphere. At the same time, oxidation reaction takes place on the surface of the anode hemisphere to provide more reactive surfaces, which can effectively improve the removal rate of nitrate and current utilization, reduce the energy loss, and strengthen the electrochemical system. At the same time, the reduction of nitrate and the oxidation of reductive by-products also occur on the cathode and anode surface, respectively.
【學(xué)位授予單位】：中國(guó)地質(zhì)大學(xué)(北京)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：X523

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本文編號(hào)：1969869