摘要
中试含能材料废水含各类高浓度含氮化合物(氨氮(NH3─N)、亚硝酸盐(NO
图文摘要
This research focuses on the removal of wastewater containing nitrogen compounds from complex energetic materials using a BDD electrode. It covers the preparation and characterization of the electrode, the impact of experimental conditions and the possible transformation path of nitrogen. The study also examines the degradation process of nitrogen‑containing compounds in the anode cell and compares the treatment effects of BDD electrodes modified by different metals as anode or cathode.
关键词
近年来随着工业化进程的加速,环境问题日趋严重,从水资源和废水中去除含氮化合物亟需解决。化工、军工产业中含能材料的大量使用,导致地下水、河流、湖泊和海水中的含氮化学物,尤其是氨氮(NH3─N)、亚硝酸盐(NO
电化学氧化还原法是一种被广泛应用的降解废水的方法,大量研究表明通过阳极氧化和阴极还原过程可无选择性地去除废水中大多数有机和无机污染物。在众多影响电化学氧化还原法降解废水效率的因素中,电极材料的选择尤为重要,如Fe、Cu、Al、Ni、Pb、Pt、尺寸稳定阳极(DSA)、Ti/PbO2
本研究采用热丝化学气相沉积法(HFCVD)法制备的BDD电极对高COD、高NH3─N、高NO
氯化钠试剂(AR),成都科隆化学试剂厂;硫酸钠试剂(AR),成都科隆化学试剂厂;氢氧化钠试剂(AR),成都科隆化学试剂厂;硝酸钠试剂(AR),成都科隆化学试剂厂;五水硫酸铜试剂(AR),成都科隆化学试剂厂;七水硫酸镍试剂(AR),成都科隆化学试剂厂;质子交换膜(N117),美国杜邦公司;超纯水,实验室自制。
德国Carl Zeiss公司Ultra‑55型场发射扫描电镜 (FE‑SEM);荷兰Panalytical公司X'Pert PRO型X射线衍射(XRD)仪;英国雷尼绍公司型号为InVia的激光拉曼光谱(Raman)仪;上海辰华型号为CHI 760e的电化学工作站;河北兰格恒流泵有限公司型号为BT100‑2J的蠕动泵;上海索宜电子有限公司型号为SOYI‑50200的直流电源;美国哈希DR3900可见光分光光度计;北分瑞利公司型号为SP‑3420A的气相色谱仪。
实验中使用的BDD电极通过HFCVD法制备,以高电导Si(100取向,厚1 mm,面积20 c
Cu/BDD,Ni/BDD电极以BDD电极为基底,采用电化学沉积法在三电极模式下恒电位法制备。电化学沉积Cu/BDD和Ni/BDD电极,分别采用0.5 M CuSO4和0.5 M Ni2SO4溶液为电镀液,以等面积Pt片为对电极,Ag/AgCl电极为参比电极,在0.6 V(vs. Ag/AgCl)电压下沉积5 s。为测试改性电极的电化学性能,首先将其在0.5 M NaOH溶液中采用循环伏安法进行活化,扫描速率设置为100 mV·
(1) 电极形貌表征
采用SEM和EDS对电极的表面形貌和元素分布进行表征,采用XRD测试电极的晶粒择优取向及薄膜结晶度,波长为0.15406 nm的Cu Kα辐射源、2θ扫描范围为20°~100°、入射角度为1°、扫描速度为2°·mi
(2) 无机离子浓度测试
亚硝酸盐离子测试:参考文献[
硝酸盐离子测试:参考文献[
氨氮测试:参考文献[
BDD表面沉积Cu、Ni层,以及BDD、Cu/BDD和Ni/BDD电极的电化学性能均采用标准三电极系统进行测试,分别以BDD(或Cu/BDD、Ni/BDD)为工作电极、以等面积Pt片和Ag/AgCl为对电极和参比电极。其中,计时电流法(CA)用于在BDD表面恒电位沉积Cu、Ni,循环伏安法(CV)及线性扫描伏安法(LSV)用于对电极电化学性能表征,扫描速率50 mV·
废水取自某含能材料化工厂,呈淡黄色、刺激性气味、弱碱性(pH:8.82)、高电导率(36.70 mS·c
original water sample composition | NH3─N | C | NO | NO | SO |
---|---|---|---|---|---|
concentration/mg· | 1735 | 432 | 17280 | 3128 | 153.6 |
实验采用自制的密闭电解装置对废水进行降解,其结构如

图1 电化学装置示意图
Fig.1 Schematic diagram of electrochemical device
BDD、Cu/BDD和Ni/BDD电极的表面形貌如

a. SEM and EDS images of Cu/BDD electrode

b. SEM and EDS images of Ni/BDD electrode

c. SEM image of BDD electrode
图2 Cu/BDD、Ni/BDD及BDD电极的SEM表征
Fig.2 SEM characterization of Cu/BDD, Ni/BDD and BDD electrodes

a. Raman spectrum

b. XRD pattern
图3 Cu/BDD、Ni/BDD及BDD电极的拉曼及XRD表征
Fig.3 Raman and XRD characterization of Cu/BDD, Ni/BDD and BDD electrodes

a. LSV curve in 0.1 M Na2SO4 solution

b. LSV curve in 0.1 M Na2SO4+0.01 M NaNO3 solution

c. CV curve in 0.5 M NaOH solution

d. CV curve in 0.5 M NaOH+0.5 M NH3─N solution
图4 BDD、Cu/BDD和Ni/BDD电极在不同溶液中的LSV及CV曲线
Fig.4 LSV and CV curves of BDD, Cu/BDD and Ni/BDD electrodes in different solutions.
在采用BDD电极降解有机废水的研究中,C

a. relationship between NO
and pH with time

b. relationship between NO

c. relationship between NH3─N concentration and time

d. relationship between N2 conversion rate and time
图5 添加不同电解质对含能材料废水含氮化合物降解性能的影响
Fig.5 Effect of adding different electrolytes on degradation performance of nitrogenous compounds in wastewater containing energetic materials
以上实验结果表明NaCl的加入对含氮化合物的降解影响较大,对NH3─N的去除尤为明显。这主要是在电生·OH的作用下,C
在BDD阳极上可能发生的主要反应如
(1) |
(2) |
(3) |
(4) |
(5) |
(6) |
(7) |
(8) |
(9) |
(10) |
(11) |
(12) |
(13) |
在BDD阴极上可能发生的主要反应如下:
(14) |
(15) |
(16) |
(17) |
BDD阳极协同其他阴离子可以实现对NO

a. relationship between NO
and pH with time

b. relationship between NO

c. relationship between NH3─N concentration and time

d. relationship between N2 conversion rate and time
图6 不同阴极对含能材料废水中含氮化合物降解性能的影响
Fig.6 Effects of different cathodes on the degradation performance of nitrogenous compounds in energetic material wastewater
金属修饰阴极可以加速NO

a. optical image of used
BDD electrode

b. SEM image of used Cu/BDD
electrodes

c. SEM image of used Ni/BDD
elecrodes
图7 使用后的Cu/BDD、Ni/BDD电极的光学图像及SEM表征
Fig.7 Optical images and SEM characterization of used Cu/BDD and Ni/BDD electrodes
为避免含氮化合物副反应对降解效率的影响,本研究采用双电解池结构将阴阳电极用质子交换膜隔离,阳极分别采用BDD,Cu/BDD和Ni/BDD电极,阴极采用等几何面积的不锈钢电极,设置阴阳极间距为10 mm,在80 mA·c

a. relationship between NO
and pH with time

b. relationship between NO

c. relationship between NH3─N concentration and time

d. relationship between N2 conversion rate and time
图8 双电解池体系下不同阳极对含氮化合物降解性能的影响
Fig.8 Effect of different anodes on the degradation of nitrogen-containing compounds in double electrolytic cell system
本研究通过HFCVD法制备了不同的BDD电极,分析了其形貌及电化学氧化还原性能;研究了电解质,Cu、Ni金属掺杂BDD电极分别作为阴阳极等对实际含能材料废水中含氮化合物降解处理性能的影响,主要结论如下:
(1) 在BDD电极表面沉积金属催化剂,制备了Cu/BDD,Ni/BDD电极,其表现出对硝酸盐还原和氨氮氧化良好的电化学性能。
(2) 与Na2SO4电解质相比,添加0.1 M NaCl可以提高溶液中NH3─N的降解,提升N2的转化效率;在0.1 M NaCl电解质体系下,N2的转化率为96.78%,优于0.1 M Na2SO4电解质(88.39%)和直接降解原溶液(84.80%)。
(3) 以Cu/BDD、Ni/BDD为阴极可加速NO
(4) 双电解池结构体系下,以Cu/BDD、Ni/BDD电极为阳极可以显著提高NH3─N转化为N2的降解速率,同时Cu/BDD电极的降解性能优于Ni/BDD电极;在Cu/BDD阳极体系中N2的转化率为99.01%,高于Ni/BDD阳极(98.35%)和BDD阳极(95.01%)。
(5) BDD电极降解实际含能材料废水中含氮化合物的最佳条件:在双电解池体系中,在添加0.1 M NaCl,Cu/BDD阳极处理12 h后,N2的转化率接近为99.01%。
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