生物质炭/ZnO复合材料的制备及其吸附-光催化性能
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摘要
以纳米晶纤维素(NCC)为形貌诱导模板,醋酸锌(Zn(CH_3COO)_2·2H_2O)为Zn源,采用原位聚合法制备NCC/ZnO纳米杂化物,再经550℃高温碳化,得到生物质炭/ZnO复合材料。采用TEM、XRD、BET、UV-Vis测试研究生物质炭与ZnO固体质量比(0.03∶1、0.17∶1、0.67∶1)对生物质炭/ZnO复合材料形貌、晶体结构、孔结构及光吸收性能的影响。并进一步以亚甲基蓝(MB)为模型污染物,研究生物质炭/ZnO复合材料的吸附-光催化性能,阐明其吸附-光催化机制。结果表明,经550℃高温碳化后,NCC转化为具有石墨微晶结构的生物质炭,其骨架结构得以保留,纳米ZnO均匀负载在生物质炭表面,形成生物质炭/ZnO复合材料。与纯纳米ZnO相比,生物质炭/ZnO复合材料比表面积显著提高,具备优异的吸附性能,同时,NCC转化得到的生物质炭有效提高了ZnO的光生电子-空穴对的分离率。生物质炭/ZnO复合材料通过吸附-光催化协同效应去除水体中的MB,去除率显著增加。当生物质炭与ZnO的固体质量比为0.17∶1时,生物质炭/ZnO复合材料的平均孔径为188.99nm,比表面积为33.51m~2/g,在室温条件下,避光吸附30min后,再使用500W紫外灯照射20min,即对MB降解率达到99.8%。
The nano crystalline cellulose(NCC)/ZnO nano hybrids were prepared with a procedure of in-situ polymerization using NCC as a morphological-inducing template,and Zn acetate(Zn(CH_3COO)_2·2H_2O)as a Zn source,respectively.The NCC/ZnO nano hybrids were then carbonized at 550~oC to obtain biochar/ZnO composites.The morphology,crystal structure,pore texture and light absorption performance of biochar/ZnO composites influenced by a mass ratio of biochar to ZnO(0.03∶1,0.17∶1,0.67∶1)were characterized by TEM,XRD,BET and UV-Vis spectroscopy.The adsorption-photocatalysis performance of biochar/ZnO composites was investigated through removing methylene blue(MB)under UV light irradiation,and the mechanism of biochar/ZnO composites was further studied.The results indicate that the NCC transforms to biochar with graphite crystallite and skeleton structure after a carbonization process at 550℃.The nano ZnO particles are uniformly deposited on the surface of biochar,and then the biochar/ZnO composites are obtained.The obtained biochar/ZnO composites exhibit higher surface area and better absorbability compared with the neat nano ZnO.And the biochar improves the separation of photogenerated electrons and holes of ZnO.The biochar/ZnO composites remove MB with a synergistic effect of adsorption and photocatalysis.In particular,the biochar/ZnO composite has an average pore diameter of 188.99nm,and a specific surface area of 33.51m~2/g respectively at the mass ratio of 0.17∶1(biochar to ZnO).Consequently,the biochar/ZnO composite has an optimum degradation efficiency to MB,corresponding to 99.8%degradation rate of MB after the absorption for 30min in dark condition and continuous irradiation for 20min under 500W UV light at room temperature.
The nano crystalline cellulose(NCC)/ZnO nano hybrids were prepared with a procedure of in-situ polymerization using NCC as a morphological-inducing template,and Zn acetate(Zn(CH_3COO)_2·2H_2O)as a Zn source,respectively.The NCC/ZnO nano hybrids were then carbonized at 550~oC to obtain biochar/ZnO composites.The morphology,crystal structure,pore texture and light absorption performance of biochar/ZnO composites influenced by a mass ratio of biochar to ZnO(0.03∶1,0.17∶1,0.67∶1)were characterized by TEM,XRD,BET and UV-Vis spectroscopy.The adsorption-photocatalysis performance of biochar/ZnO composites was investigated through removing methylene blue(MB)under UV light irradiation,and the mechanism of biochar/ZnO composites was further studied.The results indicate that the NCC transforms to biochar with graphite crystallite and skeleton structure after a carbonization process at 550℃.The nano ZnO particles are uniformly deposited on the surface of biochar,and then the biochar/ZnO composites are obtained.The obtained biochar/ZnO composites exhibit higher surface area and better absorbability compared with the neat nano ZnO.And the biochar improves the separation of photogenerated electrons and holes of ZnO.The biochar/ZnO composites remove MB with a synergistic effect of adsorption and photocatalysis.In particular,the biochar/ZnO composite has an average pore diameter of 188.99nm,and a specific surface area of 33.51m~2/g respectively at the mass ratio of 0.17∶1(biochar to ZnO).Consequently,the biochar/ZnO composite has an optimum degradation efficiency to MB,corresponding to 99.8%degradation rate of MB after the absorption for 30min in dark condition and continuous irradiation for 20min under 500W UV light at room temperature.
引文
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[29]ZHAO D,SHENG G,CHEN C,et al.Enhanced photocatalytic degradation of methylene blue under visible irradiation on graphene@TiO2dyade structure[J].Applied Catalysis B:Environmental,2012,111-112:303-308.
[30]ZHAO D,YANG X,CHEN C,et al.Enhanced photocatalytic degradation of methylene blue on multiwalled carbon nanotubes-TiO2[J].Journal of Colloid&Interface Science,2013,398:234-239.
[2]MA S,XUE J,ZHOU Y,et al.A facile route for the preparation of ZnO/C composites with high photocatalytic activity and adsorption capacity[J].Crystengcomm,2014,16(21):4478-4484.
[3]SAMPAIO M J,OLIVEIRA J W L,SOMBRIO C I L,et al.Photocatalytic performance of Au/ZnO nanocatalysts for hydrogen production from ethanol[J].Applied Catalysis A:General,2016,518:198-205.
[4]QIAN C,GAO Y,GAO T,et al.Insight into biological effects of zinc oxide nanoflowers on bacteria:Why morphology matters[J].ACS Applied Materials&Interfaces,2016,8(16):10109-10120.
[5]SIN J C,LAM S M,LEE K T,et al.Preparation of flowerlike ZnO hierarchical structures for photodegradation of phenol under UV irradiation[J].Research on Chemical Intermediates,2013,41(4):2489-2502.
[6]铁伟伟,张艳鸽,郑直,等.含共轭结构的ZnO/聚乙烯醇复合光催化材料的制备与性能[J].复合材料学报,2016,33(7):1423-1428.TIE W W,ZHANG Y G,ZHENG Z,et al.Fabrication and properties of ZnO/poly(vinylalcohol)composite photocatalyst materials with conjugation structure[J].Acta Materiae Compositae Sinica,2016,33(7):1423-1428(in Chinese).
[7]YU H Y,CHEN G Y,WANG Y B,et al.A facile one-pot route for preparing cellulose nanocrystal/zinc oxide nanohybrids with high antibacterial and photocatalytic activity[J].Cellulose,2015,22(1):261-273.
[8]晁成.细菌纤维素模板效应制备光催化剂杂化纤维及其光催化性能研究[D].南京:南京理工大学,2013.CHAO C.Preperation of photocatalyst hydrid fiber by bacterial cellulose’s template effect and research of its photocatalytic properties[D].Nanjing:Nanjing University of Science and Technology,2013(in Chinese).
[9]KOLODZIEJCZAK A,JESIONOWSKI T.Zinc oxide-from synthesis to application:A review[J].Materials,2014,7(4):2833-2881.
[10]GUO Y,WANG H,HE C,et al.Uniform carbon-coated ZnO nanorods:Microwave-assisted preparation,cytotoxicity,and photocatalytic activity[J].Langmuir:the ACS Journal of Surfaces&Colloids,2009,25(8):4678-84.
[11]WANG X,KONG X,YU Y,et al.Synthesis and characterization of water-soluble and bifunctional ZnO-Au nanocomposites[J].Journal of Physical Chemistry C,2007,111(10):3836-3841.
[12]LIAO L,LI J C,WANG D F,et al.Field emission property improvement of ZnO nanowires coated with amorphous carbon and carbon nitride films[J].Nanotechnology,2005,16(6):985-989.
[13]MU J,SHAO C,GUO Z,et al.High photocatalytic activity of ZnO-carbon nanofiber heteroarchitectures[J].ACS Applied Materials&Interfaces,2011,3(2):590-596.
[14]CAI X,LI J,LIU Y,et al.Titanium dioxide-coated biochar composites as adsorptive and photocatalytic degradation materials for the removal of aqueous organic pollutants[J].Journal of Chemical Technology&Biotechnology,2018,93(3):783-791.
[15]雷蕾.生物质炭及TiO2/生物质炭复合材料的制备及其在污水处理中的应用[D].兰州:西北师范大学,2015.LEI L.Preparation and application of biomass activated carbon and TiO2/biomass activated carbon in waste water[D].Lanzhou:Northwest Normal University,2015(in Chinese).
[16]于长江,王苗,董心雨,等.海藻酸钙@Fe3O4/生物碳磁性复合材料的制备及其对Co(Ⅱ)的吸附性能和机制[J].复合材料学报,2018,35(6):1549-1557.YU C J,WANG M,DONG X Y,et al.Preparation and characterization of calcium alginate@Fe3O4/biochar magnetic microsphere and its adsorption characteristcs and mechanism[J].Acta Materiae Compositae Sinica,2018,35(6):1549-1557(in Chinese).
[17]CHO S,JANG J W,LEE J S,et al.Carbon-doped ZnO nanostructures synthesized using vitamin C for visible light photocatalysis[J]. Crystengcomm, 2010, 12(11):3929-3935.
[18]WANG S,ZHOU Y,HAN S,et al.Carboxymethyl cellulose stabilized ZnO/biochar nanocomposites:Enhanced adsorption and inhibited photocatalytic degradation of methylene blue[J].Chemosphere,2018,197:20-25.
[19]潘明珠,连海兰.生物质纳米材料的制备及其功能应用[M].北京:科学出版社,2016.PAN M Z,LIAN H L.Preparation and function application of biomass nanomaterials[M].Beijing:Science Press,2016(in Chinese).
[20]JAZAERI E,TSUZUKI T.Effect of pyrolysis conditions on the properties of carbonaceous nanofibers obtained from freeze-dried cellulose nanofibers[J].Cellulose,2013,20(2):707-716.
[21]LEE S,LEE M E,SONG M Y,et al.Morphologies and surface properties of cellulose-based activated carbon nanoplates[J].Carbon Letters,2016,20(1):32-38.
[22]CHEN D,ZHU H,YANG S,et al.Micro-nanocomposites in environmental management[J]. Advanced Materials,2016,28(47):10443-10458.
[23]YU C T,CHEN W H,MEN L C,et al.Microscopic structure features changes of rice straw treated by boiled acid solution[J].Industrial Crops&Products,2009,29(2):308-315.
[24]马立波.纳米纤维素及其碳化材料增强热塑性塑料的研究[D].南京:南京林业大学,2016.MA L B.Study of nano cellulose and its carbonized products reinforced in thermoplastics[D].Nanjing:Nanjing Forestry University,2016(in Chinese).
[25]LI Q,RENNECKAR S.Supramolecular structure characterization of molecularly thin cellulose I nanoparticles[J].Biomacromolecules,2011,12(3):650-659.
[26]刘冲.吸附光催化协同提高有机物降解能力的研究[D].唐山:华北理工大学,2017.LIU C.Adsorption photocatalysis synergistic effect during the enhanced photocatalytic degradation of organic pollutants[D].Tangshan:North China University of Science and Technology,2017(in Chinese).
[27]吴鹏,刘志明,谢成.针状ZnO的纳米纤维素诱导制备及光催化性能[J].纤维素科学与技术,2014,22(4):1-5.WU P,LIU Z M,XIE C.Nanocrystalline cellulose induced preparation and photocatalytic properties of needle-like ZnO[J].Journal of Cellulose Science and Technology,2014,22(4):1-5(in Chinese).
[28]LI N,JIANG J,CHEN D,et al.A reusable immobilization matrix for the biodegradation of phenol at 5 000 mg/L[J].Scientific Reports,2015,5:08628.
[29]ZHAO D,SHENG G,CHEN C,et al.Enhanced photocatalytic degradation of methylene blue under visible irradiation on graphene@TiO2dyade structure[J].Applied Catalysis B:Environmental,2012,111-112:303-308.
[30]ZHAO D,YANG X,CHEN C,et al.Enhanced photocatalytic degradation of methylene blue on multiwalled carbon nanotubes-TiO2[J].Journal of Colloid&Interface Science,2013,398:234-239.