水蒸汽浴FeS_2高效Fenton降解甲草胺（英文）_江吉周.pdf

物 理 化 学 学 报 Acta Phys.-Chim.Sin.2023,39(3),2209033(1 of 10)Received:September 21,2022;Revised:October 14,2022;Accepted:October 25,2022;Published online:October 31,2022.*Corresponding authors.Emails:(H.W.);(J.H.).This work was supported by the National Natural Science Foundation of China(62004143,21876209),Key R&D Program of Hubei Province,China(2022BAA084),Natural Science Foundation of Hubei Province,China(2021CFB133),the Central Government Guided Local Science and Technology Development Special Fund Project,China(2020ZYYD033),the Open Research Fund of Key Laboratory of Material Chemistry for Energy Conversion and Storage,China(HUST),Ministry of Education,China(2021JYBKF05)and the Innovation Project of Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education,China(LCX2021003),the Opening Fund of Key Laboratory for Green Chemical Process of Ministry of Education of Wuhan Institute of Technology,China(GCP202101).国家自然科学基金(62004143,21876209),湖北省重点研发计划(2022BAA084),湖北省自然科学基金(2021CFB133),中央引导地方科技发展专项基金(2020ZYYD033),能量转换与存储材料化学教育部重点实验室开放基金(2021JYBKF05),磷资源开发利用教育部工程研究中心创新项目(LCX2021003),武汉工程大学绿色化工程教育部重点实验室开放基金(GCP202101)资助项目 Editorial office of Acta Physico-Chimica SinicaArticle doi:10.3866/PKU.WHXB202209033 Water Steam Bathed FeS2 for Highly Efficient Fenton Degradation of Alachlor Jizhou Jiang 1,Lianglang Yu 1,Fangyi Li 1,Wenming Deng 1,Cong Pan 2,Haitao Wang 1,*,Jing Zou 1,Yaobin Ding 2,Fengxia Deng 3,Jia Huang 1,*1 School of Environmental Ecology and Biological Engineering,School of Chemistry and Environmental Engineering,School of Chemical Engineering and Pharmacy,Key Laboratory of Green Chemical Engineering Process of Ministry of Education,Engineering Research Center of Phosphorus Resources Development and Utilization of Ministry of Education,Novel Catalytic Materials of Hubei Engineering Research Center,Wuhan Institute of Technology,Wuhan 430205,China.2 College of Resources and Environmental Science,South-Central Minzu University,Wuhan 430074,China.3 State Key Laboratory of Urban Water Resources and Environment,School of Environment,Harbin Institute of Technology,Harbin 150090,China.Abstract:Fenton-like activity of iron sulfides for the generation of reactive oxygen species and degradation of various organic pollutants has been extensively investigated due to its abundance in the natural environment.However,their Fenton-like activity is usually unsatisfactory due to the limited exposure of surface ferrous reactive sites.In this work,a new strategy to enhance the Fenton-like activity of iron sulfides,using pyrite(FeS2)as a model,was developed based on the heat treatment of FeS2 by water steam.It was found that the FeS2 heat-treated by water steam(Heat-FeS2)exhibited much higher heterogeneous Fenton activity in the degradation of alachlor(ACL)than its parent FeS2 prepared from hydrothermal reaction(Fresh-FeS2).At an initial pH of 6.3,the rate of degradation of ACL by Heat-FeS2 Fenton system was 0.48 min1,which is 23 times higher than that of Fresh-FeS2 Fenton system.Electron spin resonance analysis and benzoic acid probe experiments confirmed the production of more hydroxyl(OH)and superoxide radicals(O2)in Heat-FeS2 Fenton system than Fresh-FeS2 Fenton system.The increased Fenton-like activity of Heat-FeS2 can be attributed to the increased content of highly reactive surface bonded Fe2+/Fe3+species,higher amount of leached Fe2+,and optimal reaction pH due to stronger acidification of Heat-FeS2.Characterization studies by scanning electron microscopy,transmission electron microscopy,X-ray photoelectron spectroscopy(XPS),and Fourier-transform infrared spectroscopy showed that heat treatment remarkably promoted the transformation of lattice Fe2+to surface reactive Fe2+,allowing the exposure of more surface reactive Fe2+and leaching of Fe2+;simultaneously,heat treatment enhanced the generation of surface SO42,creating a highly acidic surface.The surface Fe2+percentage in the surface total iron was raised from 13%in Fresh-FeS2 to 29%in Heat-FeS2.Fe2+leaching from Heat-FeS2 was 0.23 mmolL1,much higher than that(0.02 mmolL1)for Fresh-FeS2.The change in the surface Fe and S species in the Heat-FeS2 system during the Fenton-like reaction was monitored by XPS to elucidate the enhanced Fenton oxidation mechanism.The characterization results 物理化学学报 Acta Phys.-Chim.Sin.2023,39(3),2209033(2 of 10)showed that after Fenton reaction with H2O2,the surface contents of Fe2+and Fe3+species on Fresh-FeS2 and Heat-FeS2 were remarkably raised,while the surface content of S22 species was reduced,confirming the crucial role of S22 in the reductive cycle of Fe3+to Fe2+.These findings increase understanding of the oxidative transformation and corrosion of iron sulfides and its relevant transformation and degradation of toxic organics in natural environments.The results of this work also provide an efficient Fenton-like oxidation method based on iron sulfides for highly efficient degradation of organic pollutants(e.g.ACL)in aqueous solution.Key Words:FeS2;Water steam treatment;Fenton;Surface Fe2+species;Alachlor 水蒸汽浴水蒸汽浴 FeS2高效高效 Fenton 降解甲草胺降解甲草胺 江吉周1，余良浪1，李方轶1，邓文明1，潘聪2，王海涛1,*，邹菁1，丁耀彬2，邓凤霞3，黄佳1,*1武汉工程大学，环境生态与生物工程学院，化学与环境工程学院，化工与制药学院，绿色化工程教育部重点实验室，磷资源开发利用教育部工程研究中心，新型催化材料湖北省工程研究中心，武汉 430205 2中南民族大学，资源与环境学院，武汉 430074 3哈尔滨工业大学，环境学院，城市水资源与水环境国家重点实验室，哈尔滨 150090 摘要：摘要：由于硫化铁在自然环境中的丰富性，其生成活性氧和降解各种有机污染物的类Fenton活性已被广泛研究。然而，由于表面含铁活性位点的暴露有限，它们的类Fenton活性通常不高。在本研究中，以黄铁矿(FeS2)为例，基于水蒸汽对FeS2的热处理，开发了一种提高硫化铁矿物Fenton活性的新策略，研究发现经水蒸汽热处理后的FeS2(Heat-FeS2)对甲草胺(ACL)的非均相Fenton活性比由水热反应制备的母体FeS2(Fresh-FeS2)更高。在初始pH为6.3时，Heat-FeS2-Fenton体系对ACL的降解速率为0.48 min1，约为Fresh-FeS2-Fentton体系的23倍。电子自旋共振分析和苯甲酸探针实验证实，与Fresh-FeS2-Fenton体系相比，在Heat-FeS2-Fenton体系中产生更多的羟基自由基(OH)和超氧自由基(O2)。Heat-FeS2的Fenton活性大幅增强主要可归因于含量增加的高活性表面Fe2+/Fe3+组份、较高的Fe2+浸出量和最佳的反应pH条件。扫描电镜，透射电镜，X射线光电子能谱(XPS)和傅里叶变换红外光谱等一系列表征结果表明，热处理可显著促进晶格Fe2+向表面活性Fe2+的转化，同时增强表面SO42的生成，从而形成高酸性表面。此外，热处理后Fresh-FeS2表面Fe2+在表面总铁中的百分比从13%提高到了Heat-FeS2的29%，而且Heat-FeS2的Fe2+浸出量(0.23 mmolL1)也远高于Fresh-FeS2的Fe2+浸出量(99%)were obtained from Sinopharm Chemical Reagent Co.,Ltd.(China).All the chemicals were of analytical grade and used without further purification.2.2 Catalyst preparation and characterization FeS2 was firstly prepared according to a modified hydrothermal synthesis method 30.Specially,FeSO47H2O,Na2S2O35H2O and S with the same molar quantity(0.02 mol)were dispersed in 60 mL deionized water and stirred at room temperature for 0.5 h.Subsequently,it was put into in a polytetrafluoroethylene-lined stainless steel autoclave with the volume of 100 mL.After sealing,it was heated to 200 C and kept for 24 h for hydrothermal reaction.The formed products were recycled by centrifugation and washing with distilled water and ethanol three times.Finally,after drying in vacuum atmosphere at 60 C for 6 h,the sample was obtained and named as Fresh-FeS2.To prepare Heat-FeS2,the obtained Fresh-FeS2 sample was ground and uniformly distributed on a glass dish.After covered with another glass dish,they were put into a thermostatic water bath filled with water to float on water.The temperature of the bath was set to 85 C,and the sample was heated in the closed water steam environment for 6 h.Meanwhile,another two heat treatment methods(vacuum dry and dry in air)at the same temperature were also used for modification of Fresh-FeS2 as comparison.The as-prepared Fresh-FeS2 and Heat-FeS2 samples were characterized by scanning electron microscope(SEM,GeminiSEM 300,Germany),transmission electron microscopy(TEM,JEM-2100,Japan),X-ray powder diffraction(XRD,AXS D8,Germany),and X-ray photoelectron spectra(XPS,VG Multilab 2000,Thermo Scientific,USA).2.3 Fenton oxidation experiments The Fenton oxidation capacity of two FeS2 samples was assessed via degradation of ACL.The concentration of ACL was 20 mgL1(0.074 mmolL1).The dosage of FeS2 samples was 0.5 gL1.The concentration of H2O2 was 0.8 mmolL1.The degradation of ACL was conducted under shaking with a rotary shaker at 25 C.The initial pH(pH0)of the degradation solution was 6.3.If necessary,it was adjusted by adding 0.5 molL1 HCl or NaOH.After sampling at regular intervals using a syringe and removing FeS2 solid by filtration via a 0.22 m microporous filter,the obtained 2.7 mL of sample was mixed rapidly with 0.3 mL of a 15 molL1 glycerol solution to terminate Fenton oxidation reaction of ACL.The residual ACL was analyzed by high performance liquid chromatography(HPLC).物理化学学报 Acta Phys.-Chim.Sin.2023,39(3),2209033(4 of 10)2.4 Analytic methods The 1,10-phenanthroline method was used to quantify the dissolved ferrous and ferric ions.The identification of free radicals was conducted by using 5,5-dimethyl-1-pyrroline-N-oxide(DMPO)as a probe.The formed adducts were analyzed by electron spin resonance(ESR)spectrum(Bruker EPR A300,Germany).The concentration of OH accumulated was quantified using benzoic acid(BA)as the probe molecule 23.3 Results and discussion 3.1 Characterization It can be seen from Fig.1a that the diffraction peak signals of Fresh-FeS2 and Heat-FeS2 are sharp,which means that the obtained sample has good crystallinity.Compared with standard diffraction pattern,the main diffraction peaks of the two samples are at 28.5,33.1,37.1,40.8,47.4,56.3 and 64.3,which can be attributed to(111),(200),(210),(211),(220),(310)and(023)facets of face-centered cubic structure of pyrite(JCPDS PDF No.42-1340)30.The results indicate that the two samples are mainly composed of pyrite,and heat treatment by water steam under the tested conditions hardly changed the crystal structure of FeS2.FT-IR measurement was conducted to study the chemical structure changes before and after heat treatment of FeS2.As shown in Fig.1b,as for Fresh-FeS2,four sets of absorption bands were detected.The first group of absorption bands occurred at 601,670 and 798 cm1,which are identified as the stretching vibration of FeS band.The peaks at 1086 and 1147 cm1 are assigned to asymmetric stretching vibration of FeOOH groups.The band at 1635 cm1 confirms the occurrence of FeSO4 species.The wide band at 3434 cm1 is assigned to stretching vibration of surface OH groups 33.Worth mentioning,the intensity of all peaks of Fresh-FeS2 was increased in varying degrees after heat treatment since the oxidative corrosion of Fresh-FeS2 in water steam.The increased peak intensities can be attributed to the formation of rich surfactant groups in the process of steam heat treatment(see subsequent detailed discussion),which is crucial for the enhancement of Fenton catalytic activity.The morphology of the two samples was analyzed by SEM.Fresh-FeS2 is mainly composed of 5 m(diameter)microspheres assembled from light sliders with irregular surfaces(Fig.2a,b).As for Heat-FeS2,the microsphere structure collapses to form Fig.1 (a)XRD patterns and(b)FT-TIR spectra of Fresh-FeS2 and Heat-FeS2.Fig.2 (a,b)SEM images of Fresh-FeS2 and(c,d)Heat-FeS2 物理化学学报 Acta Phys.-Chim.Sin.2023,39(3),2209033(5 of 10)multi-sized polymers,and flocculent burrs appear on the surface(Fig.2c,d).The oxidative etching of Heat-FeS2 was also observed by TEM(Fig.S1).Heat-FeS2 exhibited more uneven structure,in which some“holes”were formed from oxidative etching induced by O2 in water steam.After the heat treatment,FeS2 still kept its crystal structure as proved by the clear crystal planes of(200)with inter-planar spacing of 0.271nm(Fig.S1).Due to the heat treatment,Heat-FeS2 showed bigger oxygen content than Fresh-FeS2.The oxygen content of Heat-FeS2 was 27.15%,while that value of Fresh-FeS2 was 5.11%(Fig.S2 and Table 1).These results indicate occurrence of corrosion of FeS2 by O2 in the water steam during its heat treatment.Meanwhile,the molar ratio of Fe/S in FeS2 was also varied due to the heat treatment.The molar ratio of Fe/S in Fresh-FeS2 was 0.6,and increased to 0.78 for Heat-FeS2(Table 1),suggesting that the heat treatment is conducive to exposure of Fe reactive sites.To further understand the change induced by the heat treatment,XPS was used to analyze the surface chemical composition of Fresh-FeS2 and Heat-FeS2.As seen in Fig.3a,b,S 2p spectrum of FeS2 was composed of S22,Sn2(n 2),S0,SO32 and SO42.Peaks centered at 162.7,163.8 and 164.4 eV are assigned to S22,Sn2(n 2)and S0,respectively 34.Peak of SO32 appeared around 166.0 eV,while peaks of SO42 occurred at higher binding energies of 168.8 and 170.0 eV 33,3537.When XPS of Fresh-FeS2 and Heat-FeS2 was compared,it can be easily seen that the intensity of peaks assigned to SO42 was obviously increased after heat treatment.In the XPS of Fe 2p of Fresh-FeS2 and Heat-FeS2(Fig.3c,d),there were a strong peak with binding energy of 707.0 eV,which belongs to lattice Fe2+of FeS2.The tail at higher binding energy can be decomposed to quadruple peaks 33,3537.The peaks at binding energy of 708.4 and 710.1 eV are assigned to Fe2+S,while those at 709.1 and 711.4 eV are assigned to Fe3+S 34.As compared with Fresh-FeS2,Heat-FeS2 exhibited obviously stronger spectrum tail of Fe 2p,especially Fe2+S and Fe3+S spectrum at 710.1 eV and 711.3 eV(Fig.3d),while the peak of Heat-FeS2 assigned to the lattice Fe2+was decreased relative to that on surface of Fresh-FeS2.These results indicate that heat treatment with water steam triggered transformation of lattice Fe2+to surface Fe2+/Fe3+.Of note,a new peak appeared at Table 1 Surface atom percentage of catalyst before and after reaction in different systems.Element Sample Fresh-FeS2 Used-Fresh-FeS2 Heat-FeS2 Used-Heat-FeS2 Fe 27.39%22.78%23.54%13.11%S 45.9%39.02%30.24%17.87%O 5.11%25.31%27.15%50.83%C 21.6%12.89%19.07%18.19%Fe/S 0.6 0.58 0.78 0.73 Fig.3 High-resolution XPS spectra of Fresh-FeS2 and Heat-FeS2:(a,b)S 2p,and(c,d)Fe 2p.物理化学学报 Acta Phys.-Chim.Sin.2023,39(3),2209033(6 of 10)binding energy of 713.4 eV in Fe 2p of Heat-FeS2(Fig.3d),which signifies the formation of iron sulfate on the Heat-FeS2 surface,consistent with the FT-IR results in Fig.1b.Based on area of each peak,the transformation of lattice Fe2+to surface Fe2+/Fe3+was further quantitatively investigated.Upon treatment with water steam,the ratio of lattice Fe2+to total Fe(2latticeFe+/Fetotal)declined from 0.76 for Fresh-FeS2 to 0.47 for Heat-FeS2(Table 2).Meanwhile,the ratios of surface Fe2+and surface Fe3+increased due to the heat treatment.For instance,the 3surfaceFe+/Fetotal ratio for Fresh-FeS2 was 0.11,and increased to 0.24 for Heat-FeS2.More importantly,the 2surfaceFe+/Fetotal ratio was raised from 0.13 for Fresh-FeS2 to 0.29 for Heat-FeS2.Taking into account the high reactivity of surface Fe2+in Fenton reaction,the remarkably increased surface Fe2+contributes to improve Fenton reactivity of Heat-FeS2 compared with Fresh-FeS2.Based on the above characterizations,an oxidative corrosion process of Fresh-FeS2 to prepare Heat-FeS2 with abundant surface iron species was proposed as seen in Fig.4.In the three-phase system,water steam(H2O molecules)and O2 can diffuse onto surface of FeS2.As a result,a thin water film for