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近年来,污水处理后作为再生水回用逐渐得到重视。2021年,国家发布《关于推进污水资源化利用的指导意见》指出,污水经无害化处理达到特定水质标准后,可作为再生水用于居民生活、生态补水、回灌地下水等。但诸多研究表明,再生水中仍能频繁检出微量抗生素等难降解有机污染物,呈现浓度低、高稳定性、高毒性和易生物富集等特性,进入水环境可诱导环境菌群产生抗药性,甚至导致超级抗药细菌的出现,对人体和生态环境产生巨大的潜在风险[1-4]。开发经济高效的污水中抗生素等微量污染物的去除技术,仍是目前污水处理领域亟需解决的重要问题之一。
高级氧化技术(advanced oxidation processes, AOPs)能够产生具有强氧化力的活性物种,可以高效降解去除上述微量高风险有机物,近年来引起了广泛的关注[5-6]。其中,基于过硫酸盐(PMS)或过二硫酸盐(PDS)活化的高级氧化技术所产生的硫酸根自由基(SO4·−)、羟基自由基(·OH)、单线态氧(1O2)等ROS,具有广谱的难降解有机污染物去除能力,且活化方法较为简单,较之芬顿体系表现出较大优势[7]。在众多活化PMS的方法中,过渡金属因其运行成本低、效率高而被广泛使用[8-9]。其中,钴(Co)被认为是最有效的PMS活化金属[10-11],然而,在PMS活化过程中,Co2+的浸出对人体健康和生态环境构成了严重威胁,因为Co2+即使在非常低的浓度下也具有高毒性和潜在致癌性[12-13]。因此,寻求绿色的过渡金属制作高效催化剂,对基于过硫酸盐活化的高级氧化技术发展尤为重要。
类水滑石(layered double hydroxide,LDHs)又称层状双金属氧化物,是一类阴离子插层的二维层状无机材料,具有层板元素和层间阴离子种类可变、比例可调、金属阳离子均匀分散等特性,在多相催化中具有广阔的应用前景。有研究[14]表明,LDHs可高效活化H2O2的过氧键(O—O),产生·OH,据此推测PMS中的O—O键亦可以被LDHs活化。然而LDHs用于活化PMS虽取得一些研究进展,但目前研究多集中于Co系二元LDHs,如ZHAO等[9]对CoMn-LDHs活化PMS降解有机染料进行了研究,发现CoMn-LDHs具有优异的催化活性。然而,Co系LDHs活化PMS仍难以避免Co2+浸出,造成严重的二次污染问题;而Mn作为Co的替代性元素对PMS的活化效能仍有待提高。有研究[15]表明,多金属掺杂可有效提高催化材料活化PMS过程中的电子传递效率,提高催化剂的催化活性,实现高效、绿色活化PMS降解抗生素等难降解有机物。然而,抗生素类微量有机物与多金属掺杂的多元LDHs表面吸附态PMS之间是否存在直接电子传递作用,并实现对这类难降解有机物的高效降解,目前仍鲜有报道。
本研究以氯四环素(chlortetracycline,CTC)为研究对象,通过水热法制备了绿色、高效的催化剂MnFeCu三元类水滑石,且将其用于活化PMS以降解CTC,分别使用扫描电镜(scanning electron microscope,SEM)、X射线粉末衍射(X ray diffractometer,XRD)及X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)等分析手段对催化剂的形貌和结构进行了表征和分析;考察了CTC浓度、催化剂和PMS投加量、初始pH及温度对CTC降解效能的影响;对降解过程中产生的各类活性物种进行了淬灭实验及EPR捕获,探明了活性物种的产生情况及其在CTC降解过程中的贡献,以揭示CTC的降解机制。对活化PMS前后的催化剂理化性质进行对比分析,结合催化剂回收再利用过程中CTC的降解效能,评估了催化剂的循环稳定性。本研究结果以期为水环境中抗生素的去除提供参考。
MnFeCu-LDHs活化PMS降解氯四环素的效能及机制
Degradation efficiency and mechanism of chlortetracycline by activation of peroxymonosulfate via MnFeCu-LDHs
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摘要: 针对污水处理厂尾水中抗生素等生物难降解有机物频繁检出的问题,采用相对绿色、低毒性的过渡金属元素制备了锰铁铜类水滑石(MnFeCu-LDHs),并将其用于活化过一硫酸盐(PMS)降解氯四环素(CTC)。探究了初始pH、反应温度、催化剂和PMS投量对CTC降解效能的影响规律,通过化学捕获和淬灭实验确定了活性氧物种(ROS)的种类与贡献,并对反应前后的催化剂进行理化性质表征且考察了催化剂稳定性。结果表明,在初始pH为7、反应温度为298 K、催化剂及PMS投加量均为0.2 g·L−1条件下,反应5 min后CTC去除率达到80.88%,30 min去除率达到91.18%,同时,随着初始pH和温度的提高,CTC的降解效果得到明显增强;ROS淬灭实验和EPR捕获实验结果证实了在该体系中,·OH、SO4·−、1O2均参与了CTC的降解,贡献度最高的是1O2,其次为·OH和SO4·−;基于反应前后XPS光谱对比分析,发现MnFeCu-LDHs活化PMS过程稳定性较好,此外该催化剂在重复使用5次后,CTC的30 min去除率仍达到73.61%。因此,本研究可为SR-AOPs应用于控制水环境抗生素类污染提供新思路。
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关键词:
- MnFeCu-LDHs /
- 过一硫酸盐 /
- 高级氧化技术 /
- 氯四环素 /
- 氧化降解
Abstract: Aiming at frequent detection of biorefractory organics, such as antibiotics in the tail water of wastewater treatment plant, MnFeCu layered double hydroxide (MnFeCu-LDHs) was prepared with green and low toxic transition metals to activate persulfate (PMS) for degrading chlortetracycline (CTC). The effects of initial pH, reaction temperature, catalyst and PMS dosage on CTC degradation efficiency were investigated. The types and contributions of reactive oxygen species (ROS) were determined through chemical capture and quenching experiments. The physicochemical properties of catalysts before and after reaction were characterized to investigate the stability of catalysts. The results showed that the removal rate of CTC reached 80.88% after 5 min reaction, and 91.18% after 30 min reaction when the initial pH was 7, the reaction temperature was 298 K, and the dosages of catalyst and PMS were 0.2 g·L−1. Meanwhile, with the increase of initial pH and temperature, the degradation effect of CTC increased significantly. ROS quenching experiment and EPR capture confirmed that ·OH, SO4·− and 1O2 participated in CTC degradation in this system, of which the highest contribution was 1O2, followed by ·OH and SO4·−. Based on the comparative analysis results of XPS spectra before and after the reaction, it was found that the stability of MnFeCu-LDHs activated PMS process was reliable. In addition, after five recycles of the catalyst, the CTC degradation rate still reached 73.61% at 30 min reaction. Therefore, this study would provide a new insight for the application of SR-AOPs to control antibiotic pollution in water environment.-
Key words:
- MnFeCu-LDHs /
- peroxymonosulfate /
- advanced oxidation processes /
- chlortetracycline /
- degradation
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[1] 曲久辉, 赵进才, 任南琪, 等. 城市污水再生与循环利用的关键基础科学问题[J]. 中国基础科学, 2017, 19: 6-12. doi: 10.3969/j.issn.1009-2412.2017.05.002 [2] 卫先宁, 季民, 李茹莹. 再生水中药品及个人护理品分布和环境风险分析[J]. 环境科学与技术, 2021, 43(12): 1-6. doi: 10.19672/j.cnki.1003-6504.2020.12.028 [3] BEN W W, ZHU B, YUAN X J, et al. Occurrence, removal and risk of organic micropollutants in wastewater treatment plants across China: Comparison of wastewater treatment processes[J]. Water Research, 2017, 130: 38-46. [4] MIKLOS D B, REMY C, JEKEL M, et al. Evaluation of advanced oxidation processes for water and wastewater treatment: A critical review[J]. Water research, 2018, 139: 118-131. doi: 10.1016/j.watres.2018.03.042 [5] LIU J, YANG Q, WANG D, et al. Enhanced dewaterability of waste activated sludge by Fe (II)-activated peroxymonosulfate oxidation[J]. Bioresource technology, 2016, 206: 134-140. doi: 10.1016/j.biortech.2016.01.088 [6] BOCZKAJ G, FERNANDES A. Wastewater treatment by means of advanced oxidation processes at basic pH conditions: A review[J]. Chemical Engineering Journal, 2017, 320: 608-633. doi: 10.1016/j.cej.2017.03.084 [7] PANG X, GUO Y, ZHANG Y, et al. LaCoO3 perovskite oxide activation of peroxymonosulfate for aqueous 2-phenyl-5-sulfobenzimidazole degradation: Effect of synthetic method and the reaction mechanism[J]. Chemical Engineering Journal, 2016, 304: 897-907. doi: 10.1016/j.cej.2016.07.027 [8] OH W D, DONG Z, LIM T T. Generation of sulfate radical through heterogeneous catalysis for organic contaminants removal: Current development, challenges and prospects[J]. Applied Catalysis B:Environmental, 2016, 194: 169-201. doi: 10.1016/j.apcatb.2016.04.003 [9] ZHAO X, NIU C, ZHANG L, et al. Co-Mn layered double hydroxide as an effective heterogeneous catalyst for degradation of organic dyes by activation of peroxymonosulfate[J]. Chemosphere, 2018, 204: 11-21. doi: 10.1016/j.chemosphere.2018.04.023 [10] GERKEN J B, MCALPIN J G, CHEN J Y C, et al. Electrochemical water oxidation with cobalt-based electrocatalysts from pH 0–14: the thermodynamic basis for catalyst structure, stability, and activity[J]. Journal of the American Chemical Society, 2011, 133(36): 14431-14442. doi: 10.1021/ja205647m [11] GUO W, SU S, YI C, et al. Degradation of antibiotics amoxicillin by Co3O4-catalyzed peroxymonosulfate system[J]. Environmental progress & sustainable energy, 2013, 32(2): 193-197. [12] SIMONSEN L O, HARBAK H, BENNEKOU P. Cobalt metabolism and toxicology: A brief update[J]. Science of the Total Environment, 2012, 432: 210-215. doi: 10.1016/j.scitotenv.2012.06.009 [13] FENG Y, WU D, ZHOU Y, et al. A metal-free method of generating sulfate radicals through direct interaction of hydroxylamine and peroxymonosulfate: Mechanisms, kinetics, and implications[J]. Chemical Engineering Journal, 2017, 330: 906-913. doi: 10.1016/j.cej.2017.08.034 [14] FAN X, CAO Q, MENG F, et al. A Fenton-like system of biochar loading Fe–Al layered double hydroxides (FeAl-LDH@ BC)/H2O2 for phenol removal[J]. Chemosphere, 2021, 266: 128992. doi: 10.1016/j.chemosphere.2020.128992 [15] XU X, LIN R, DENG X, et al. In situ synthesis of FeOOH-coated trimanganese tetroxide composites catalyst for enhanced degradation of sulfamethoxazole by peroxymonosulfate activation[J]. Separation and Purification Technology, 2021, 275: 119184. doi: 10.1016/j.seppur.2021.119184 [16] 吴德勇, 苏积珊. Cu2O/CuO/BC复合材料活化PMS降解TC[J]. 环境科学与技术, 2022, 45(3): 188-196. [17] 林陆健, 汤帅, 孙璇, 等. 铅离子和四环素在微塑料表面的吸附机理与协同效应[J]. 环境科学学报, 2021, 41(10): 4022-4031. doi: 10.13671/j.hjkxxb.2021.0052 [18] ZENG H, ZHANG W, DENG L, et al. Degradation of dyes by peroxymonosulfate activated by ternary CoFeNi-layered double hydroxide: Catalytic performance, mechanism and kinetic modeling[J]. Journal of colloid and interface science, 2018, 515: 92-100. doi: 10.1016/j.jcis.2018.01.016 [19] WANG G, LI D, WANG S, et al. Ternary NiFeMn layered metal oxide (LDO) compounds for capacitive deionization defluoridation: The unique role of Mn[J]. Separation and Purification Technology, 2021, 254: 117667. doi: 10.1016/j.seppur.2020.117667 [20] HOU L, LI X, YANG Q, et al. Heterogeneous activation of peroxymonosulfate using Mn-Fe layered double hydroxide: Performance and mechanism for organic pollutant degradation[J]. Science of the Total Environment, 2019, 663: 453-464. doi: 10.1016/j.scitotenv.2019.01.190 [21] GONG C, CHEN F, YANG Q, et al. Heterogeneous activation of peroxymonosulfate by Fe-Co layered doubled hydroxide for efficient catalytic degradation of Rhoadmine B[J]. Chemical engineering journal, 2017, 321: 222-232. doi: 10.1016/j.cej.2017.03.117 [22] AHMADI M, GHANBARI F. Combination of UVC-LEDs and ultrasound for peroxymonosulfate activation to degrade synthetic dye: Influence of promotional and inhibitory agents and application for real wastewater[J]. Environmental Science and Pollution Research, 2018, 25(6): 6003-6014. doi: 10.1007/s11356-017-0936-8 [23] HUANG G X, WANG C Y, YANG C W, et al. Degradation of bisphenol A by peroxymonosulfate catalytically activated with Mn1.8Fe1.2O4 nanospheres: Synergism between Mn and Fe[J]. Environmental Science & Technology, 2017, 51(21): 12611-12618. [24] DENG J, WU G, YUAN S, et al. Ciprofloxacin degradation in UV/chlorine advanced oxidation process: Influencing factors, mechanisms and degradation pathways[J]. Journal of Photochemistry and Photobiology A:Chemistry, 2019, 371: 151-158. doi: 10.1016/j.jphotochem.2018.10.043 [25] TAN Y, LI C, SUN Z, et al. Natural diatomite mediated spherically monodispersed CoFe2O4 nanoparticles for efficient catalytic oxidation of bisphenol A through activating peroxymonosulfate[J]. Chemical Engineering Journal, 2020, 388: 124386. doi: 10.1016/j.cej.2020.124386 [26] LI Z, SUN Y, HUANG W, et al. Innovatively employing magnetic CuO nanosheet to activate peroxymonosulfate for the treatment of high-salinity organic wastewater[J]. Journal of Environmental Sciences, 2020, 88: 46-58. doi: 10.1016/j.jes.2019.07.011 [27] XU Y, AI J, ZHANG H. The mechanism of degradation of bisphenol A using the magnetically separable CuFe2O4/peroxymonosulfate heterogeneous oxidation process[J]. Journal of Hazardous Materials, 2016, 309: 87-96. doi: 10.1016/j.jhazmat.2016.01.023 [28] DUAN P, MA T, YUE Y, et al. Fe/Mn nanoparticles encapsulated in nitrogen-doped carbon nanotubes as a peroxymonosulfate activator for acetamiprid degradation[J]. Environmental Science:Nano, 2019, 6(6): 1799-1811. doi: 10.1039/C9EN00220K [29] YANG S, WU P, LIU J, et al. Efficient removal of bisphenol A by superoxide radical and singlet oxygen generated from peroxymonosulfate activated with Fe0-montmorillonite[J]. Chemical Engineering Journal, 2018, 350: 484-495. doi: 10.1016/j.cej.2018.04.175 [30] DONG X, REN B, SUN Z, et al. Monodispersed CuFe2O4 nanoparticles anchored on natural kaolinite as highly efficient peroxymonosulfate catalyst for bisphenol A degradation[J]. Applied Catalysis B:Environmental, 2019, 253: 206-217. doi: 10.1016/j.apcatb.2019.04.052