發(fā)布時間：2018-01-07 11:19

  本文關(guān)鍵詞：電催化反硝化去除水中硝酸鹽實驗研究　出處：《沈陽工業(yè)大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 電催化反硝化 雙金屬電極 硝酸鹽 選擇性

【摘要】：隨著工農(nóng)業(yè)的快速發(fā)展,全國各地水體中硝酸鹽的污染日益嚴(yán)重,給人類健康帶來極大的危害,所以我國飲用水衛(wèi)生標(biāo)準(zhǔn)嚴(yán)格規(guī)定硝酸鹽的濃度要低于10 mg/L。由于硝酸鹽在還原過程中會產(chǎn)生一些副產(chǎn)物,很難將硝酸鹽全部轉(zhuǎn)化為氮氣,因此開發(fā)一種高效、高選擇性、低成本的硝酸鹽處理方法成為值得關(guān)注的研究方向。近年來電催化反硝化技術(shù)以其綠色環(huán)保的優(yōu)勢日漸受到研究者的關(guān)注。在電催化反硝化陰極材料中,雙金屬材料的研究逐漸發(fā)展為一種趨勢,雙金屬電極在電催化活性和反應(yīng)選擇性方面有很高的可塑性,應(yīng)用前景良好。本課題采用恒電流電鍍法制備了Cu-M(M代表Bi和Sn)兩種雙金屬電極,其中Cu-Bi電極在電催化反硝化領(lǐng)域鮮有研究,是一種新型電催化反硝化電極。同時優(yōu)化了兩種電極的制備條件,深入研究了兩種電極的電催化反硝化性能。實驗按照相應(yīng)的配方配制鍍液并恒電流電鍍雙金屬鍍層,考察了電鍍電流密度對電極鍍層的穩(wěn)定性和元素組成的影響,通過在單室反應(yīng)器中恒電流電解硝酸鈉模擬廢水,詳細(xì)分析討論了電流密度、初始pH值和硝酸鹽初始濃度對硝酸鹽去除效果和還原產(chǎn)物組成的影響,比較了Cu-Bi和Cu-Sn兩種電極的電催化反硝化性能。通過以上實驗研究結(jié)果進行分析討論,得到以下結(jié)論:(1)電鍍電流密度對電極鍍層的穩(wěn)定性影響較大。采用自制Cu-Bi電極的新配方鍍液,電鍍Cu-Bi電極的最佳電流密度為6 mA/cm~2,得到的鍍層表面致密均勻、穩(wěn)定性較好,無燒焦現(xiàn)象。電鍍Cu-Sn雙金屬電極的最佳電流密度為4 mA/cm~2,得到的鍍層表面顆粒均勻一致、粗糙度較高,有利于催化。(2)以Cu-Bi雙金屬電極為陰極,釕銥電極為陽極,硝酸鹽氮初始濃度為100 mg/L,Na2SO4濃度為0.125 mol/L,電流密度為6 mA/cm~2,初始pH值為7的條件下,電催化還原處理4 h后,硝酸鹽氮的去除率達87.5%,總氮去除率為60.7%,生成的亞硝酸鹽氮濃度為3.74 mg/L,氨氮濃度為16.95 mg/L,電流效率約為34%。(3)以Cu-Sn雙金屬電極為陰極,釕銥電極為陽極,硝酸鹽氮初始濃度為100 mg/L,Na2SO4濃度為0.125 mol/L,電流密度為10 mA/cm~2,電解液為堿性的條件下,電催化還原處理4 h后,硝酸鹽氮的去除率為34%,產(chǎn)物中沒有檢測到亞硝酸鹽氮,氨氮的選擇性為100%,電流效率為8%。(4)Cu-Bi雙金屬電極電催化反硝化去除硝酸鹽的效果明顯優(yōu)于Cu-Sn雙金屬電極,而Cu-Sn電極可將硝酸鹽氮全部轉(zhuǎn)化為氨氮,沒有其他副產(chǎn)物。Cu-Bi電極在中性條件下效果更好,而Cu-Sn電極在堿性條件下效果較好。(5)Cu-Bi雙金屬電極對硝酸鹽的還原伴隨著析氫反應(yīng)的發(fā)生,Cu-Sn雙金屬電極還原硝酸鹽的反應(yīng)在析氫反應(yīng)之前發(fā)生。鍍層中銅元素的含量的增加有助于提高電極的電催化活性。
[Abstract]:With the rapid development of industry and agriculture, water nitrate pollution in the country is becoming increasingly serious, bring great harm to human health, so our country's drinking water standard, strict rules of nitrate concentration lower than 10 mg/L. due to nitrate will produce some by-products in the reduction process, it is difficult to be completely transformed into nitrate nitrogen, therefore the development of a high efficiency, high selectivity, low cost nitrate treatment method has become a research direction of concern. In recent years the catalytic denitrification technology with its green advantages have become increasingly concerned. In the electro catalytic denitrification in cathode materials, the research of double metal materials gradually developed into a trend double metal electrode, high plasticity in the electrocatalytic activity and selectivity, good application prospect. This paper adopts constant current electroplating method to prepare Cu-M (M Bi and Sn) two Double metal electrode, the Cu-Bi electrode in a few studies of electro catalytic denitrification field, is a new type of catalytic denitrification electrode. At the same time, two kinds of electrode preparation conditions were optimized, in-depth study of the electro catalytic denitrification performance of two kinds of electrodes. In accordance with the corresponding experimental formula of plating solution and plating metal double constant current the effects of coating, electroplating current density on electrode coating stability and elemental composition, the single chamber reactor in constant current electrolysis of sodium nitrate wastewater, analysed and discussed the influence of current density, initial pH value and initial concentration of nitrate on nitrate removal and reduction of product composition, electric catalysis Cu-Bi Cu-Sn and nitrification performance of two kinds of electrodes were compared. Through the above analysis and discussion of experimental results, obtained the following conclusions: (1) the plating current density on the stability of electrode coating is greatly affected by. The new formula of self-made Cu-Bi electrode plating solution, plating electrode Cu-Bi optimum current density is 6 mA/cm~2, the coating surface compact uniform, good stability, no burning phenomenon. The optimal current density of electroplating Cu-Sn double metal electrode is 4 mA/cm~2, the coating particles are uniform, high roughness, is conducive to catalysis. (2) to Cu-Bi double metal electrode as cathode, ruthenium and iridium electrode as anode, the initial concentration of nitrate nitrogen was 100 mg/L, the concentration of Na2SO4 was 0.125 mol/L, the current density is 6 mA/cm~2, the initial pH value is 7, the electrocatalytic reduction of H 4, the nitrate nitrogen removal rate of 87.5% and the total nitrogen removal rate was 60.7%, nitrite nitrogen concentration generated for 3.74 mg/L, the concentration of ammonia nitrogen is 16.95 mg/L, the current efficiency is about 34%. (3) Cu-Sn double metal electrode as cathode, ruthenium and iridium electrode as anode, the initial concentration of nitrate nitrogen was 100 mg/L, the concentration of Na2SO4 was 0.125 Mol/L, the current density is 10 mA/cm~2, the electrolyte is alkaline conditions, the electrocatalytic reduction after 4 h treatment, the nitrate nitrogen removal rate was 34%, the product was not detected in the nitrite nitrogen, ammonia nitrogen selectivity was 100%, the current efficiency is 8%. (4) Cu-Bi double metal electrode catalytic denitrification removal of nitric acid salt is better than that of Cu-Sn double metal electrode and Cu-Sn electrode can be converted to ammonium nitrate and other byproducts of.Cu-Bi electrode have better performance under neutral conditions, and better effect of Cu-Sn electrode in alkaline condition. (5) Cu-Bi double metal electrode on nitrate reduction with hydrogen evolution reaction occurrence of nitrate Cu-Sn double metal electrode reduction reaction before the hydrogen evolution reaction. The content of copper element in the coating increase helps to improve the electrocatalytic activity of the electrode.

【學(xué)位授予單位】：沈陽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X703.1

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