天然黑钨矿可见光催化活性的实验研究
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摘要
天然半导体矿物具有优良的日光催化特性。本研究选取天然钨酸盐作为研究对象,对武鸣、栗木、崇义3个不同矿区的天然黑钨矿进行了矿物学及光催化实验探究。利用X射线衍射、拉曼光谱、红外光谱、电子探针微区分析对天然样品的结构与成分进行分析,鉴定其主要矿物相为黑钨矿(Fe,Mn)[WO4],从武鸣、栗木到崇义矿区,Fe/Mn摩尔分数比从7.1、0.9到0.3依次降低。利用紫外可见漫反射测得武鸣、栗木、崇义地区样品禁带宽度分别为1.5、1.6和1.7eV,说明其具有良好的可见光响应。在pH为7的条件下用质量浓度为1g/L的样品对5mg/L的有机染料亚甲基蓝(MB)进行光催化实验(含0.01mol/L H_2O_2 ),结果表明武鸣地区黑钨矿实验组降解MB的效果最佳,3h后其效率分别是栗木、崇义地区样品的1.1倍和1.6倍。电子顺磁共振谱检测结果显示,反应过程中均产生氧化性羟自由基(·OH),其中效果最好的武鸣黑钨矿产生的·OH信号更强;不同自由基捕获实验证明·OH在光催化反应过程中起主要作用。进一步选取武鸣黑钨矿开展光催化降解机制研究,实验结果显示:光照下黑钨矿与H_2O_2 共存的实验组对MB的脱色降解率可达99%(3h),只有黑钨矿的对照组降解7%的MB,只有H_2O_2 的对照组降解31%的MB;黑暗条件下,同时添加黑钨矿与H_2O_2 的对照组对MB的去除率为34%。不同H_2O_2 浓度条件下黑钨矿降解MB符合准一级动力学方程,说明降解过程与催化剂含量无关,H_2O_2 更多的是充当电子受体。分析认为,不同产地黑钨矿日光催化效率与矿物铁含量呈正相关,与禁带宽度呈负相关,推测其反应机理是光催化与芬顿反应协同产生的·OH将MB氧化降解。本研究为开发利用天然矿物治理环境污染提出了新方法。
Natural semiconducting minerals have excellent solar photocatalytic properties.In this study,we selected natural wolframite as the research object.We performed mineralogical and photocatalytic experiments using natural wolframite from three mining areas:Wuming(WM),Limu(LM)and Chongyi(CY).We used Xray diffraction,Raman and infrared spectroscopy,and electron probe microanalysis to analyze the structure and composition of natural samples.The main mineral phases were identified as natural wolframite in the form of(Fe,Mn)WO4 with decreasing Fe/Mn molar ratios at 7.1,0.9 and 0.3 for WM,LM and CY mines,respectively.The forbidden band widths for the three mines were 1.5,1.6 and 1.7 eV,respectively,indicating agood visible light response.Photocatalytic experiments were performed at pH 7.The concentrations of wolframite and methylene blue(MB)were 1 g/L and 5 mg/L,respectively,with 0.01 mol/L H_2O_2 in the degradation solution.The results showed that the degradation efficiency of WM wolframite was the highest,equaling to 1.1 and 1.6 times that of LM and CY wolframite,respectively.Free radical·OH was detected in all solutions during the reaction by electron paramagnetic resonance(EPR),with the stronger signal coming from WM wolframite.·OH was demonstrated as the major reactive oxygen species by using different scavenger in the photocatalytic reaction.The experimental results further showed that the rate of MB decolorization degradation was up to 99%(after 3 hours)in the experimental group where both wolframite and H_2O_2 were used under light.In the control group,wolframite or H_2O_2 was used and the MB degradation rates were only7% and 31% after 3 hours,respectively.Under darkroom condition,the MB removal rate was 34% with additions of wolframite and H2 O2.Degradation of MB in wolframite under different H_2O_2 concentrations was analyzed and found to conform to quasi-first-order kinetics,indicating the degradation process was independent of catalyst content,and H_2O_2 was more likely to act as an electron acceptor.According to our analysis,under sunlight,the catalytic efficiency of wolframite from all producing areas was positively correlated with Fe content and negatively correlated with band gap width,for which the suggested reaction mechanism involves MB oxidative degradation by ·OH generated by photocatalytic and Fenton reactions.Our study presented a new method of utilizing natural minerals for environmental pollution remediation.
Natural semiconducting minerals have excellent solar photocatalytic properties.In this study,we selected natural wolframite as the research object.We performed mineralogical and photocatalytic experiments using natural wolframite from three mining areas:Wuming(WM),Limu(LM)and Chongyi(CY).We used Xray diffraction,Raman and infrared spectroscopy,and electron probe microanalysis to analyze the structure and composition of natural samples.The main mineral phases were identified as natural wolframite in the form of(Fe,Mn)WO4 with decreasing Fe/Mn molar ratios at 7.1,0.9 and 0.3 for WM,LM and CY mines,respectively.The forbidden band widths for the three mines were 1.5,1.6 and 1.7 eV,respectively,indicating agood visible light response.Photocatalytic experiments were performed at pH 7.The concentrations of wolframite and methylene blue(MB)were 1 g/L and 5 mg/L,respectively,with 0.01 mol/L H_2O_2 in the degradation solution.The results showed that the degradation efficiency of WM wolframite was the highest,equaling to 1.1 and 1.6 times that of LM and CY wolframite,respectively.Free radical·OH was detected in all solutions during the reaction by electron paramagnetic resonance(EPR),with the stronger signal coming from WM wolframite.·OH was demonstrated as the major reactive oxygen species by using different scavenger in the photocatalytic reaction.The experimental results further showed that the rate of MB decolorization degradation was up to 99%(after 3 hours)in the experimental group where both wolframite and H_2O_2 were used under light.In the control group,wolframite or H_2O_2 was used and the MB degradation rates were only7% and 31% after 3 hours,respectively.Under darkroom condition,the MB removal rate was 34% with additions of wolframite and H2 O2.Degradation of MB in wolframite under different H_2O_2 concentrations was analyzed and found to conform to quasi-first-order kinetics,indicating the degradation process was independent of catalyst content,and H_2O_2 was more likely to act as an electron acceptor.According to our analysis,under sunlight,the catalytic efficiency of wolframite from all producing areas was positively correlated with Fe content and negatively correlated with band gap width,for which the suggested reaction mechanism involves MB oxidative degradation by ·OH generated by photocatalytic and Fenton reactions.Our study presented a new method of utilizing natural minerals for environmental pollution remediation.
引文
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[14]LIN H,TAN G Q,Zhang W,et al.Microwave-assisted hydrothermal preparation chara-cterization and photocatalytic properties of a chrysanthemum-shaped ZnWO4photocatalyst[J].Journal Cluster Science,2013,24:315-325.
[15]WU W Q,QIN W H,HE Y M,et al.The effect of pH value on the synthesis and photocatalytic performance of MnWO4nanostructure by hydrothermal method[J].Experimental Nanoscience,2012,4:390-398.
[16]HE H Y,HUANG J F,CAO L Y,et al.Photodegradation of methyl orange aqueous on MnWO4powder under different light resources and initial pH[J].Desalination,2010,252:66-70.
[17]CHAKRABORTY A K,GANGULI S,KEBEDE M A.Photocatalytic degradation of 2-propanol and phenol using Au loaded MnWO4 nanorod under visible light irradiation[J].Clust Science,2012,23:437-448.
[18]MONIZ S J A,SHEVLIN S A,MARTIN D J,et al.Visible-light driven heterojunction photocatalysts for water splitting:a critical review[J].Energy Environment Science,2015,8:731-759.
[19]OBER J A.Mineral commodity summaries[M].Reston:United State Geological Survey,2018:178-179.
[20]潘兆橹,赵爱醒,潘铁虹.结晶学及矿物学[M].北京:地质出版社,1998:1-232.
[21]李水如,王登红,梁婷,等.广西大明山钨矿区成矿时代及其找矿前景分析[J].地质学报,2008,82(7):873-879.
[22]杜金亮.广西栗木钨锡矿田构造特征及构造控矿机制探讨[D].桂林:桂林理工大学,2012:1-63.
[23]徐敏林,漆富勇,赵磊,等.江西崇义淘锡坑大型钨矿床成矿花岗岩体研究[J].资源调查与环境,2011,32(2):120-128.
[24]VIELHAUER S,BABIN V,DE G M,et al.Self-quenching effects of excitons in CaWO4under high density XUV free electron laser excitations[J].Physics of Solid State,2008,50(9):1789-1794.
[25]FEDOROV N,NAGIRNYI V,VASIL'EV A,et al.Use of luminescent materials for the metrology of intense UVXbundles of ultrashort impulsions[J].Physics,2006,138:251-257.
[26]佟文明.尺寸效应和掺杂效应对纳米AWO4(A=Mn、Cd、Ca、Zn)结构及性质的影响[D].呼和浩特:内蒙古大学,2010.
[27]GAO Q X,LIU Z J.FeWO4nanorods with excellent UV-Visible light photocatalysis[J].Progress in Natural Science:Materials International,2017,27:556-560.
[28]周佩玲.赣南钨矿床中黑钨矿和白钨矿的红外光谱探讨[J].矿物学报,1984(4):33-36.
[29]HELAILI N,BOUDJAMAA A,KEBIR M,et al.Efficient photo-catalytic degradation of malachite green using nickel tungstate material as photo-catalyst[J].Environment Science Pollution Research,2017,24:6481-6491.
[30]DAI R C,DING X,WANG Z P,et al.Pressure and temperature dependence of Raman scattering of MnWO4[J].Chemical Physics Letters,2013,586:76-80.
[31]MANIFACIER J C,GASIOT J,FILLARD J P.A simple method for the determination of the optical constants n,k and the thickness of a weakly absorbing thin film[J].Journal of Physics E:Scientific Instruments,1976,9(11):1002-1004.
[32]ZHANG Z,WANG W,SHANG M,et al.Photocatalytic degradation of rhodamine B and phenol by solution combustion synthesized BiVO4photocatalyst[J].Catalysis Communications,2010,11:982-986.
[33]黄伟英,刘菲,鲁安怀,等.过氧化氢与过硫酸钠去除有机污染物的进展[J].环境科学与技术,2013,36(9):88-95.
[34]NIE X M,WULAYIN W,SONG T T,et al.Scheelite-type semiconductor InBi3(MoO6)2 nanoparticles:preparation,structural and optical properties[J].Journal of the Taiwan Institute of Chemical Engineers,2017,74:263-271.
[35]田斐.电子捕获剂协同载贵金属TiO2光催化降解典型制药污染物[D].哈尔滨:哈尔滨工业大学,2011.
[2]CHEN X B,SHEN S H,GUO L J,et al.Semiconductorbased photocatalytic hydrogen generation[J].Chemical Review,2010,110:6503-6570.
[3]何洪波,薛霜霜,余长林.钨基半导体光催化剂研究进展[J].有色金属科学与工程,2015,6(5):33-38.
[4]刘守新,刘鸿.光催化与光电催化基础与应用[M].北京:化学工业出版社,2006:1-350.
[5]YE J H,ZOU Z G,OSHIKIRI M,et al.A novel hydrogenevolving photocatalyst InVO4active under visible light irradiation[J].Chemical Physics Letters,2002,356:221-226.
[6]CHANG W K,RAO K K,KUO H C,et al.A novel coreshell like composite In2O3@CaIn2O4for efficient degradation of Methylene Blue by visible light[J].Applied Catalysis A:General,2007,321:1-6.
[7]KUDO A,KATO H.Photocatalytic activities of Na2W4O13with layered structure[J].Chemistry Letters,1997,26:421-422.
[8]HOSSEINPOUR-MASHKANI S M,SOBHANI-NASAB A.Simple synthesis and characterization of copper tungstate nanoparticles:investigation of surfactant effect and its photocatalyst application[J].Materials in Electronics,2016,27:7548-7553.
[9]El-SHEIKH S M,RSHAD M M.Novel synthesis of cobalt nickel tungstate nanopowders and its photocatalytic application[J].Journal Cluster Science,2015,26(3):743-757.
[10]BAI X J,WANG L,ZHU Y F.Visible photocatalytic activity enhancement of ZnWO4by graphene hybridization[J].Catalysis,2012,2:2769-2778.
[11]XIOMARA A L,ANTONIO F F,MIGUEL M Z,et al.Synthesis,characterization and photocatalytic evaluation of MWO4(MNi,Co,Cu and Mn)tungstates[J].International Journal of Hydrogen Energy,2016,41:23312-23317.
[12]ZHANG L S,WONG K H,YIP H Y,et al.Effective photocatalytic disinfection of E.coli K-12using AgBr-Ag-Bi2WO6nanojunction system irradiated by visible light:the role of diffusing hydroxyl radicals[J].Environmental Science and Technology,2010,44(4):1392-1398.
[13]ZHOU Y X,YAO H B,ZHANG Q,et al.Hierarchical FeWO4 microcrystals:solvothermal synthesis and their photocatalytic and magnetic properties[J].Inorganic Chemistry,2009,48:1082-1090.
[14]LIN H,TAN G Q,Zhang W,et al.Microwave-assisted hydrothermal preparation chara-cterization and photocatalytic properties of a chrysanthemum-shaped ZnWO4photocatalyst[J].Journal Cluster Science,2013,24:315-325.
[15]WU W Q,QIN W H,HE Y M,et al.The effect of pH value on the synthesis and photocatalytic performance of MnWO4nanostructure by hydrothermal method[J].Experimental Nanoscience,2012,4:390-398.
[16]HE H Y,HUANG J F,CAO L Y,et al.Photodegradation of methyl orange aqueous on MnWO4powder under different light resources and initial pH[J].Desalination,2010,252:66-70.
[17]CHAKRABORTY A K,GANGULI S,KEBEDE M A.Photocatalytic degradation of 2-propanol and phenol using Au loaded MnWO4 nanorod under visible light irradiation[J].Clust Science,2012,23:437-448.
[18]MONIZ S J A,SHEVLIN S A,MARTIN D J,et al.Visible-light driven heterojunction photocatalysts for water splitting:a critical review[J].Energy Environment Science,2015,8:731-759.
[19]OBER J A.Mineral commodity summaries[M].Reston:United State Geological Survey,2018:178-179.
[20]潘兆橹,赵爱醒,潘铁虹.结晶学及矿物学[M].北京:地质出版社,1998:1-232.
[21]李水如,王登红,梁婷,等.广西大明山钨矿区成矿时代及其找矿前景分析[J].地质学报,2008,82(7):873-879.
[22]杜金亮.广西栗木钨锡矿田构造特征及构造控矿机制探讨[D].桂林:桂林理工大学,2012:1-63.
[23]徐敏林,漆富勇,赵磊,等.江西崇义淘锡坑大型钨矿床成矿花岗岩体研究[J].资源调查与环境,2011,32(2):120-128.
[24]VIELHAUER S,BABIN V,DE G M,et al.Self-quenching effects of excitons in CaWO4under high density XUV free electron laser excitations[J].Physics of Solid State,2008,50(9):1789-1794.
[25]FEDOROV N,NAGIRNYI V,VASIL'EV A,et al.Use of luminescent materials for the metrology of intense UVXbundles of ultrashort impulsions[J].Physics,2006,138:251-257.
[26]佟文明.尺寸效应和掺杂效应对纳米AWO4(A=Mn、Cd、Ca、Zn)结构及性质的影响[D].呼和浩特:内蒙古大学,2010.
[27]GAO Q X,LIU Z J.FeWO4nanorods with excellent UV-Visible light photocatalysis[J].Progress in Natural Science:Materials International,2017,27:556-560.
[28]周佩玲.赣南钨矿床中黑钨矿和白钨矿的红外光谱探讨[J].矿物学报,1984(4):33-36.
[29]HELAILI N,BOUDJAMAA A,KEBIR M,et al.Efficient photo-catalytic degradation of malachite green using nickel tungstate material as photo-catalyst[J].Environment Science Pollution Research,2017,24:6481-6491.
[30]DAI R C,DING X,WANG Z P,et al.Pressure and temperature dependence of Raman scattering of MnWO4[J].Chemical Physics Letters,2013,586:76-80.
[31]MANIFACIER J C,GASIOT J,FILLARD J P.A simple method for the determination of the optical constants n,k and the thickness of a weakly absorbing thin film[J].Journal of Physics E:Scientific Instruments,1976,9(11):1002-1004.
[32]ZHANG Z,WANG W,SHANG M,et al.Photocatalytic degradation of rhodamine B and phenol by solution combustion synthesized BiVO4photocatalyst[J].Catalysis Communications,2010,11:982-986.
[33]黄伟英,刘菲,鲁安怀,等.过氧化氢与过硫酸钠去除有机污染物的进展[J].环境科学与技术,2013,36(9):88-95.
[34]NIE X M,WULAYIN W,SONG T T,et al.Scheelite-type semiconductor InBi3(MoO6)2 nanoparticles:preparation,structural and optical properties[J].Journal of the Taiwan Institute of Chemical Engineers,2017,74:263-271.
[35]田斐.电子捕获剂协同载贵金属TiO2光催化降解典型制药污染物[D].哈尔滨:哈尔滨工业大学,2011.