格造句摘要
共食采用电化学方法生成磷酸铵镁从而回收污水中的氮、磷正越来越受到人们的关注，但由于污水中氨氮的浓度常远远高于镁和磷酸盐浓度，在应用过程中存在氨氮去除率不高的问题。为此，本课题研发了一种基于磷酸铵镁沉淀的电化学强化脱氮方法，通过氨氮的电化学沉淀和电化学氧化两个过程的协同，以提高磷酸铵镁工艺中氨氮的去除率。研究得到的主要成果如下：
①在构建的Mg/改性石墨毡电极电化学反应器中，可同时发生电化学沉淀反应和阴极氧化反应，有效地提高了污水中的氮磷回收和去除效果。在相同的电化学参数条件下，反应120min时，Mg/改性石墨毡电极反应器与Mg /不锈钢电极反应器对磷的去除率均达到了97%，但前者对氨氮去除率较后者提高了4.2%。
②在Mg/改性石墨毡电极电化学反应器中，沉淀反应是氨氮的主要去除途径，生成的沉淀产物以磷酸铵镁为主。同时，采用改性石墨毡作为阴极能产生一定量的H2O2，可将氨氮氧化为N2，从而提高氨氮的去除率。
③在构建的Mg/Pt电极双向脉冲电化学反应器中，溶液中交替发生电化学磷酸铵镁沉淀反应和阳极氧化反应，大幅提高了废水中的氨氮的去除效果。在同样的电化学参数条件下，双向脉冲电解对氨氮去除率比单向脉冲氧化和单向脉冲沉淀的去除率分别高出了59.5%和10%。
④占空比、电压、频率、初始pH以及进水N:P等因素对氨氮和磷酸根离子的去除率有显著影响。增大占空比，会增加电化学磷酸铵镁沉淀反应的比重，减少电化学氧化反应的比重，在占空比为35%时，电解180min，污水中氨氮的去除率达到95%以上；通过对调节电压可以改变溶液中电流的大小，进而改变反应速率；溶液初始pH的提高会导致电化学磷酸铵镁沉淀反应提前发生，进而影响污染物随时间的去除规律；增加进水N:P比，可以提高电化学沉淀反应生成磷酸铵镁的纯度，但氨氮的去除率有所降低。
⑤氨氮的去除途径受到占空比等因素的显著影响。在占空比为45%时，电化学沉淀反应是氨氮的主要去除途径，沉淀产物以磷酸铵镁和磷酸镁为主。氨氮的电化学氧化产物以N2为主。
⑥电解过程中极板的钝化主要在Mg电极，XRD, ICP-MS和元素分析的结果表明钝化物成分主要是Mg(OH)2。当Mg电极处于低电位时，电极表面产生的H2可以加速钝化层的脱落，从而减弱钝化对电解反应的抑制作用。另外，通过超
景深三维显微镜和SEM对极板进行表征，结果表明增大电压可以减缓电极钝化，增加频率会促进钝化物在极板表面的沉积。
关键词：氨氮，脉冲电化学，镁电极，电化学氧化，磷酸铵镁
ABSTRACT
Struvite crystallization with electrochemical method has gained interest to rec over nitrogen and phosphate from wastewater. However，since wastewater usually have a large molar excess of NH4+-N relative to PO43-，removal efficiency of a mmonia nitrogen was usually low in struvite process. Hence, an electrochemical method bad on struvite process, which coupled the electrochemical precipitation and electrochemical oxidation to reinforce ammonia removal, was developed to i mprove the removal rate of ammonia nitrogen in struvite process. The main resu lts of the study are as follows:
①In the electrochemical reactor with Mg/modified graphite electrode, the el ectrochemical precipitation and cathode oxidation occurred simultaneously in solut ion, which could improve the recovery/removal effect of nitrogen and phosphorus in solution. Under the same electrochemical parameters, both of the Mg/modifie d graphite electrode and Mg/steel electrode reactor provided a more than 97% re moval rate of phosphorus, while the removal rate of ammonia nitrogen was 4.2% higher than that of the latter.
②In the Mg/modified graphite electrode reactor, the electrochemical precipit ation reaction was the
main removal route of ammonia nitrogen,and the compos ition of precipitation produced was mainly struvite. The modified graphite cathod e can produce a certain amount of H2O2, which could oxidize ammonia to N2a nd promote the removal of ammonia.
一江水吉他谱>物理教案③In the electrochemical reactor with Mg/Pt electrode, the electrochemical p recipitation reaction and anodic oxidation reaction occurred alternately in the solu tion, which was shown to be an effective method to removal/recover ammonia a nd phosphorus. Under the same electrochemical parameters, the removal rate of a mmonia nitrogen in the pul rever electrolysis was 59.5% and 10%, which w as higher than that of puld oxidation and puld precipitation respectively.
④Many factors have a significant effect on the removal rate of ammonia n itrogen and PO43-, Such as duty cycle, voltage, frequency and initial pH. With d uty cycle increasing, the proportion of the electrochemical precipitation reaction i ncread, and the proportion of the electrochemical oxidation reaction reduced. W hen duty cycle was 35%, the removal rate of ammonia was more than 95% afte
r 180min. The voltage affected the rate of the reaction by changing the magnitu de of the current in the solution. The electrolysis frequency has strong influence on the current and electrode passivatio
n. By the way of increasing the initial pH, the precipitation in the solution occured earlier, which affected the removal of p ollutants. While increasing the influent N: P ratio can improve purity of struvite, but the removal rate of ammonia nitrogen was reduced..
⑤Ammonia removal path was significantly affected by duty cycle factor. A t 45% duty cycle, the precipitation reaction was the main removal route of amm onia nitrogen, and the precipitated product was mainly struvite and magnesium p hosphate.
⑥The result of XRD, ICP-MS and elemental analysis showed that the pa ssivation of the plate was mainly Mg(OH)2in the Mg electrode in the process o f electrolysis. When the Mg electrode was at low potential, the H2produced on the surface of the electrode can destroy the passivation layer，which will inhibit the occurrence of passivation. What’s more，electrolytic voltage and frequency ha d a significant effect on electrode passivation. The plates were characterized by s uperficial depth of 3D microscopy and SEM. The results showed that the passiva tion of Mg electrode was slowed down with the voltage increasing and promoted with the frequency increasing.
Keywords: Ammonia, Pul rever electrolysis，Magnesium electrode, Electroch emical oxidation, Struvite precipitation
宝宝上吐下泻
目录
中文摘要 ................................................................................................................................................. I 英文摘要 .............................................................................................................................................. I II 1 绪论. (1)
1.1 研究背景 (1)
1.1.1 氨氮的主要来源 (1)
1.1.2 水体中氨氮的处理方法 (1)
1.2 磷酸铵镁沉淀法研究进展 (4)
1.2.1 磷酸铵镁沉淀结晶机理 (4)
1.2.2 电化学磷酸铵镁法 (6)
1.3 氨氮电化学氧化技术研究进展 (8)
1.3.1 氨氮的电化学氧化机理 (8)
1.3.2 脉冲电化学技术概述 (10)
和善1.4 研究目的及研究内容 (11)
1.4.1 研究目的 (11)
1.4.2 研究内容 (11)
论的多音字组词1.4.3 研究路线 (12)
1.4.4 研究创新点 (12)
2 实验材料与方法 (14)
2.1 实验材料 (14)
2.1.1 电极材料及其制备 (14)
2.1.2 电化学反应装置 (14)
2.1.3 实验药品及试剂 (16)
之后的英语2.1.4 测试仪器与设备 (16)
2.2 实验方法 (17)
2.2.1 电化学沉淀与阴极氧化协同处理氨氮研究 (17)
2.2.2 电化学沉淀与阳极氧化协同处理氨氮研究 (18)
2.3 测试分析方法 (20)
2.3.0 常规分析方法 (20)
2.3.1 X射线衍射 (21)
2.3.2 元素分析和ICP-MS (21)
2.3.3 数码显微镜图像 (21)
