太阳光/Fe(Ⅱ)/柠檬酸/激活过硫酸盐对污水二级出水中罗红霉素的降解效能

郑琴琴; 张若琦; 闫于飞; 蔡峰; 丁淳; 李威

doi:10.7524/j.issn.0254-6108.2021021001

南京林业大学南方现代林业协同创新中心，生物与环境学院，南京，210037

通讯作者: E-mail：uwliwei@163.com

基金项目:

国家自然科学基金（31700441）和南京林业大学大学生创新训练项目（2019NFUSPITP0764）资助

Degradation of roxithromycin in secondary effluent by persulfate activated by the combination of sunlight, Fe(Ⅱ) and citric acid

Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China

Corresponding author: LI Wei, uwliwei@163.com

Fund Project: the National Natural Science Foundation of China (31700441) and Students Practice Innovation and Training Program of Nanjing Forestry University (2019NFUSPITP0764)

摘要: 本文以柠檬酸作为Fe(Ⅱ)的螯合剂，引入模拟太阳光强化Fe(Ⅱ)/柠檬酸/螯合物活化过硫酸盐（PS）氧化降解污水处理厂二级出水中的罗红霉素，探讨了该体系对罗红霉素的降解效果、影响因素、活性物种的贡献和降解路径。结果表明，太阳光/Fe(Ⅱ)/柠檬酸/PS体系能有效降解罗红霉素，在Fe(Ⅱ)浓度为0.25 mmol·L⁻¹，PS为4 mmol·L⁻¹，Fe(Ⅱ)/柠檬酸物质的量比为1∶2，反应60 min时，罗红霉素的去除率可达到92%以上。淬灭实验表明，·OH是反应体系的主要活性物种，其对罗红霉素降解的贡献为78.3%—86.4%，而${\rm{SO}}_4^{\cdot -} $的作用相对较弱，其贡献仅为7.3%—12.5%。基于高效液相色谱高分辨质谱鉴别出8种罗红霉素的降解产物，它们主要是由罗红霉素的肟侧链断裂（—C₄H₈O₂）、脱克拉定糖（—C₈H₁₄O₃）和脱羟胺（—NH₂OH）形成的，其中DP679（C₃₃H₆₃O₁₂N₂）和DP749（C₃₇H₆₉O₁₃N₂）是最主要的降解产物。

Abstract: In this study, citric acid was used as the chelating agent of Fe(Ⅱ), and simulated sunlight was introduced to enhance the degradation of roxithromycin in secondary wastewater by persulfate (PS) activated by Fe(Ⅱ)-citrate chelate complex. The removal efficiency, impact factors, contribution of active species and degradation pathway of roxithromycin were examined. The results showed that sunlight / Fe(Ⅱ) / citrate / PS system can degrade roxithromycin effectively. When Fe(Ⅱ) concentration was 0.25 mmol·L⁻¹, PS concentration was 4 mmol·L⁻¹, molar ratio of Fe(Ⅱ) / citrate was 1∶2, and reaction time was 60 min, the removal efficiency of roxithromycin reached higher than 92%. Quenching experiments showed that ·OH was the principal active species in the reaction system, and its contribution to the degradation of roxithromycin was 78.3%—86.4%; In contrast, ${\rm{SO}}_4^{\cdot-} $ played a minor role in the degradation of roxithromycin, with the contribution of only 7.3%—12.5%. Eight degradation products (DPs) of roxithromycin were identified using high performance liquid chromatography and high resolution mass spectrometry. They were mainly formed by the cleavage of C₄H₈O₂ from the oxime side chain, cleavage of cladinose (C₈H₁₄O₃) and hydroxylamine (NH₂OH). DP679 (C₃₃H₆₃O₁₂N₂) and DP749 (C₃₇H₆₉O₁₃N₂) were the primary degradation products.

Key words:

反应体系（物质的量比）
Reaction system

一级动力学
Pseudo-first order kinetic

二级动力学
Second order kinetics

k₁/min⁻¹

R²

k₂/（L·mol⁻¹·s⁻¹）

R²

黑暗/Fe(Ⅱ)/PS

0.001

0.9564

1.6143

0.9593

太阳光/Fe(Ⅱ)/PS

0.0016

0.9886

2.8060

0.9887

太阳光/Fe(Ⅱ)/柠檬酸(1∶1.5）
Sunlight/Fe(Ⅱ)/citrate(1∶1.5)

0.0024

0.8957

4.0228

0.9042

太阳光/Fe(Ⅱ)/柠檬酸1∶2）
Sunlight/Fe(Ⅱ)/citrate(1∶2)

0.0045

0.9082

8.5515

0.9247

黑暗/Fe(Ⅱ)/柠檬酸/PS(1∶1.5)
Dark/Fe(Ⅱ)/citrate/PS(1∶1.5)

0.0013

0.7795

2.5793

0.7887

黑暗/Fe(Ⅱ)/柠檬酸/PS(1∶2)
Dark/Fe(Ⅱ)/citrate/PS(1∶2)

0.0018

0.8343

3.1015

0.8428

太阳光/Fe(Ⅱ)/柠檬酸/PS(1∶1.5)
Sunlight/Fe(Ⅱ)/citrate/PS(1∶1.5)

0.0103

0.9848

22.866

0.9962

太阳光/Fe(Ⅱ)/柠檬酸/PS(1∶2）
Sunlight/Fe(Ⅱ)/citrate/PS(1∶2)

0.0409

0.9966

290.33

0.9056

Fe/柠檬酸的物质的量比
Fe(Ⅱ)/citrate

k_obs/ min⁻¹

k_EtOH/
min⁻¹

k_TBA/
min⁻¹

·OH的贡献/%
The contribution of ·OH

SO₄^·-贡献/%
The contribution of SO₄^·-

其他贡献/%
The contribution of others

1:1.5

0.0120

0.0011

0.0026

78.3

12.5

9.2

1:2

0.0397

0.0025

0.0054

86.4

7.3

6.3

　　注 [Fe(Ⅱ)]₀=0.25 mmol·L⁻¹，[PS]₀=4 mmol·L⁻¹.

化合物
Compounds

保留时间
Retention time

元素组成
Element composition

精确分子量
Accurate molecular
weight/[m+H]⁺

碎片离子
fragmentations

误差Error
(×10⁻⁶)

环和双键值
Ring double bond
equivalent（RDB）

罗红霉素
Roxithromycin

14.94

C₄₁H₇₇O₁₅N₂

837.5315

158.1173, 679.4366

−0.425

4.5

DP591

5.00

C₂₉H₅₅O₁₀N₂

591.3834

522.3422, 158.1174

−2.878

3.5

DP665

6.22

C₃₂H₆₁O₁₂N₂

665.4210

158.1172

−1.415

3.5

DP558

7.38

C₂₉H₅₂O₉N

558.3624

158.1172

−2.308

4.5

DP679

9.49

C₃₃H₆₃O₁₂N₂

679.4371

158.1172

−0.709

3.5

DP749

10.21

C₃₇H₆₉O₁₃N₂

749.4780

591.3837, 158.1171

−1.850

4.5

DP540

11.14

C₂₉H₅₀O₈N

540.3521

158.1171

−1.821

5.5

DP716

12.18

C₃₇H₆₆O₁₂N

716.4565

158.1171

−1.972

5.5

DP714

16.23

C₃₇H₆₄O₁₂N

714.4417

556.3465, 158.1171

−0.914

6.5

太阳光/Fe(Ⅱ)/柠檬酸/激活过硫酸盐对污水二级出水中罗红霉素的降解效能

通讯作者: E-mail：uwliwei@163.com

南京林业大学南方现代林业协同创新中心，生物与环境学院，南京，210037

收稿日期: 2021-02-10

网络出版日期: 2021-12-07

基金项目:

国家自然科学基金（31700441）和南京林业大学大学生创新训练项目（2019NFUSPITP0764）资助

关键词:

Degradation of roxithromycin in secondary effluent by persulfate activated by the combination of sunlight, Fe(Ⅱ) and citric acid

Corresponding author: LI Wei, uwliwei@163.com

Co-Innovation Center for Sustainable Forestry in Southern China, College of Biology and the Environment, Nanjing Forestry University, Nanjing, 210037, China

Received Date: 2021-02-10

Available Online: 2021-12-07

Fund Project: the National Natural Science Foundation of China (31700441) and Students Practice Innovation and Training Program of Nanjing Forestry University (2019NFUSPITP0764)

Keywords:

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抗生素广泛用于人类医疗和畜禽水产养殖中，以治疗疾病和促进动物生长等，其被服用后，大部分会以原形或代谢产物的形式进入到污水处理厂中^[1-2]。由于传统污水处理厂对此类生物活性物质的去除不完全，大量抗生素在污水处理厂出水中检出，其中，克拉霉素、红霉素、脱水红霉素、阿奇霉素、罗红霉素、磺胺甲恶唑、甲氧苄胺嘧啶、氧氟沙星、环丙沙星、诺氟沙星和四环素是最常检出的抗生素^[3]。这些抗生素最终通过污水处理厂出水排放进入到地表水环境中，并对非靶生物表现出不同程度的生态风险^[4]。更令人担忧的是，抗生素的普遍存在可能导致抗性细菌的产生和抗性基因的扩散传播，严重威胁人类健康^[5]。因此，必须发展有效的降解技术以削减污水处理厂出水中的抗生素。

近年来，基于UV、热、过渡金属、碳材料等活化过硫酸盐（PS）的高级氧化技术在抗生素降解方面表现出广阔的应用前景^[6]。在各种活化方式中，Fe(Ⅱ)因具有无毒、成本低和环境友好的特点，是最常用的PS活化方式之一^[7]。但是，Fe(Ⅱ)/PS体系在应用上还具有明显的缺点：Fe(Ⅱ)可与PS迅速反应生成Fe(Ⅲ)（式（1）），而Fe(Ⅲ)还原为Fe(Ⅱ)的过程则十分缓慢，这使得Fe(Ⅱ)被迅速消耗，导致PS的活化持续效果较差；而且，过量Fe(Ⅱ)还会淬灭反应体系中的${\rm{SO}}_4^{\cdot -} $和·OH（式（2）和（3）），降低对有机污染物的去除效果^[8-10]。针对以上不足，研究者提出添加Fe的螯合剂，使Fe(Ⅱ)缓慢释放并在更宽的pH范围内保持可溶状态，同时引入UV光，促进Fe(Ⅲ)向Fe(Ⅱ)的还原，充分提高Fe(Ⅱ)的利用率^[11-13]。但是，UV光的引入往往增加了处理成本，限制其推广使用。而太阳光作为一种清洁的可再生能源，也可促进Fe(Ⅲ)向Fe(Ⅱ)的光解还原，提高反应体系对污染物的降解效率^[8]。但目前有关同时引入太阳光和螯合剂强化Fe(Ⅱ)/PS对抗生素的降解的研究尚未见报道。

因此，本研究以典型抗生素罗红霉素为目标污染物，以柠檬酸作为Fe(Ⅱ)的螯合剂，研究太阳光/Fe(Ⅱ)/柠檬酸/PS高级氧化体系对污水二级出水中罗红霉素的降解效能、影响因素和降解机制，为污水中抗生素的深度处理技术的发展提供科学依据。

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