电催化反硝化去除水中硝酸盐实验研究

发布时间：2018-01-07 11:19

本文关键词：电催化反硝化去除水中硝酸盐实验研究　出处：《沈阳工业大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着工农业的快速发展,全国各地水体中硝酸盐的污染日益严重,给人类健康带来极大的危害,所以我国饮用水卫生标准严格规定硝酸盐的浓度要低于10 mg/L。由于硝酸盐在还原过程中会产生一些副产物,很难将硝酸盐全部转化为氮气,因此开发一种高效、高选择性、低成本的硝酸盐处理方法成为值得关注的研究方向。近年来电催化反硝化技术以其绿色环保的优势日渐受到研究者的关注。在电催化反硝化阴极材料中,双金属材料的研究逐渐发展为一种趋势,双金属电极在电催化活性和反应选择性方面有很高的可塑性,应用前景良好。本课题采用恒电流电镀法制备了Cu-M(M代表Bi和Sn)两种双金属电极,其中Cu-Bi电极在电催化反硝化领域鲜有研究,是一种新型电催化反硝化电极。同时优化了两种电极的制备条件,深入研究了两种电极的电催化反硝化性能。实验按照相应的配方配制镀液并恒电流电镀双金属镀层,考察了电镀电流密度对电极镀层的稳定性和元素组成的影响,通过在单室反应器中恒电流电解硝酸钠模拟废水,详细分析讨论了电流密度、初始pH值和硝酸盐初始浓度对硝酸盐去除效果和还原产物组成的影响,比较了Cu-Bi和Cu-Sn两种电极的电催化反硝化性能。通过以上实验研究结果进行分析讨论,得到以下结论:(1)电镀电流密度对电极镀层的稳定性影响较大。采用自制Cu-Bi电极的新配方镀液,电镀Cu-Bi电极的最佳电流密度为6 mA/cm~2,得到的镀层表面致密均匀、稳定性较好,无烧焦现象。电镀Cu-Sn双金属电极的最佳电流密度为4 mA/cm~2,得到的镀层表面颗粒均匀一致、粗糙度较高,有利于催化。(2)以Cu-Bi双金属电极为阴极,钌铱电极为阳极,硝酸盐氮初始浓度为100 mg/L,Na2SO4浓度为0.125 mol/L,电流密度为6 mA/cm~2,初始pH值为7的条件下,电催化还原处理4 h后,硝酸盐氮的去除率达87.5%,总氮去除率为60.7%,生成的亚硝酸盐氮浓度为3.74 mg/L,氨氮浓度为16.95 mg/L,电流效率约为34%。(3)以Cu-Sn双金属电极为阴极,钌铱电极为阳极,硝酸盐氮初始浓度为100 mg/L,Na2SO4浓度为0.125 mol/L,电流密度为10 mA/cm~2,电解液为碱性的条件下,电催化还原处理4 h后,硝酸盐氮的去除率为34%,产物中没有检测到亚硝酸盐氮,氨氮的选择性为100%,电流效率为8%。(4)Cu-Bi双金属电极电催化反硝化去除硝酸盐的效果明显优于Cu-Sn双金属电极,而Cu-Sn电极可将硝酸盐氮全部转化为氨氮,没有其他副产物。Cu-Bi电极在中性条件下效果更好,而Cu-Sn电极在碱性条件下效果较好。(5)Cu-Bi双金属电极对硝酸盐的还原伴随着析氢反应的发生,Cu-Sn双金属电极还原硝酸盐的反应在析氢反应之前发生。镀层中铜元素的含量的增加有助于提高电极的电催化活性。
[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.

【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X703.1

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