Preparation of magnetically separable mesoporous activated carbons from brown coal with Fe_3O_4
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摘要
Magnetically separable mesoporous activated carbon was prepared from brown coal in the presence of Fe_3O_4 as a bi-functional additive. Magnetic activated carbon(MAC) was characterized by lowtemperature nitrogen adsorption, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and vibrating sample magnetometry(VSM). The evolution behaviors and transition mechanism of Fe_3O_4 during the preparation of MAC were investigated. The results show that prepared MAC with 6 wt% Fe_3O_4 addition having a specific surface area and mesopore ratio of 370 m~2·g~(-1) and 55.7%, which meet the requirements of adsorption application and magnetic recovery. Highly dispersed iron-containing aggregates with the size of 0.1 lm in the MAC were observed. During the preparation of MAC, Fe_3O_4 could enhance the escape of volatiles during the carbonization. Fe_3O_4 could also accelerate burning off the carbon wall during activation, which leads to enlarging micropore size, then resulting in the generation of mesopore and macropore. As a result, a part of Fe_3O_4 converted into FeO, FeOOH, a-Fe, c-Fe, Fe_2 SiO_4 and compound of Aluminum-iron-silicon.The prepared activated carbon, which was magnetized by both of residual Fe_3O_4, reduced a-Fe and cFe, can be easily separated from the original solution by external magnetic field.
Magnetically separable mesoporous activated carbon was prepared from brown coal in the presence of Fe_3O_4 as a bi-functional additive. Magnetic activated carbon(MAC) was characterized by lowtemperature nitrogen adsorption, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and vibrating sample magnetometry(VSM). The evolution behaviors and transition mechanism of Fe_3O_4 during the preparation of MAC were investigated. The results show that prepared MAC with 6 wt% Fe_3O_4 addition having a specific surface area and mesopore ratio of 370 m~2·g~(-1) and 55.7%, which meet the requirements of adsorption application and magnetic recovery. Highly dispersed iron-containing aggregates with the size of 0.1 lm in the MAC were observed. During the preparation of MAC, Fe_3O_4 could enhance the escape of volatiles during the carbonization. Fe_3O_4 could also accelerate burning off the carbon wall during activation, which leads to enlarging micropore size, then resulting in the generation of mesopore and macropore. As a result, a part of Fe_3O_4 converted into FeO, FeOOH, a-Fe, c-Fe, Fe_2 SiO_4 and compound of Aluminum-iron-silicon.The prepared activated carbon, which was magnetized by both of residual Fe_3O_4, reduced a-Fe and cFe, can be easily separated from the original solution by external magnetic field.
Magnetically separable mesoporous activated carbon was prepared from brown coal in the presence of Fe_3O_4 as a bi-functional additive. Magnetic activated carbon(MAC) was characterized by lowtemperature nitrogen adsorption, scanning electron microscopy(SEM), transmission electron microscopy(TEM), X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and vibrating sample magnetometry(VSM). The evolution behaviors and transition mechanism of Fe_3O_4 during the preparation of MAC were investigated. The results show that prepared MAC with 6 wt% Fe_3O_4 addition having a specific surface area and mesopore ratio of 370 m~2·g~(-1) and 55.7%, which meet the requirements of adsorption application and magnetic recovery. Highly dispersed iron-containing aggregates with the size of 0.1 lm in the MAC were observed. During the preparation of MAC, Fe_3O_4 could enhance the escape of volatiles during the carbonization. Fe_3O_4 could also accelerate burning off the carbon wall during activation, which leads to enlarging micropore size, then resulting in the generation of mesopore and macropore. As a result, a part of Fe_3O_4 converted into FeO, FeOOH, a-Fe, c-Fe, Fe_2 SiO_4 and compound of Aluminum-iron-silicon.The prepared activated carbon, which was magnetized by both of residual Fe_3O_4, reduced a-Fe and cFe, can be easily separated from the original solution by external magnetic field.
引文
[1]Pietrzak R,Wachowska H,Nowicki P.Preparation of nitrogen-enriched activated carbons from brown coal.Energy Fuels 2006;20(3):1275-80.
[2]Pietrzak R,Wachowska H,Nowicki P,Babel K.Preparation of modified active carbon from brown coal by ammoxidation.Fuel Process Technol 2007;88(4):409-15.
[3]Ariyadejwanich P,Tanthapanichakoon W,Nakagawa K,Mukai SR,Tamon H.Preparation and characterization of mesoporous activated carbon from waste tires.Carbon 2003;41(1):157-64.
[4]Tang L,Zhan L,Yang GZ,Yang JH,Wang YL,Qiao WM,et al.Preparation of mesoporous carbon microsphere/activated carbon composite for electric double-layer capacitors.New Carbon Mater 2011;26(3):237-40.
[5]Hu Z,Srinivasan MP.Mesoporous high-surface-area activated carbon.Micropor Mesopor Mater 2001;43(3):267-75.
[6]Nowicki P,Pietrzak R,Wachowska H.Comparison of physicochemical properties of nitrogen-enriched activated carbons prepared by physical and chemical activation of brown coal.Energy Fuels 2008;22(6):4133-8.
[7]Lin HK,Hill EM,Oleson JL.Recovering gold from carbon fines by a gold transfer process.Miner Metall Process 2003;20(1):47-51.
[8]Oliveira LCA,Rios R,Fabris JD,Garg V,Sapag K,Lago RM.Activated carbon/iron oxide magnetic composites for the adsorption of contaminants in water.Carbon 2002;40(12):2177-83.
[9]Zhu HY,Jiang R,Xiao L,Zeng GM.Preparation,characterization,adsorption kinetics and thermodynamics of novel magnetic chitosan enwrapping nanosized c-Fe2O3and multi-walled carbon nanotubes with enhanced adsorption properties for methyl orange.Bioresour Technol 2010;101(14):5063-9.
[10]Pardasani D,Kanaujia PK,Purohit AK,Shrivastava AR,Dubey DK.Magnetic multi-walled carbon nanotubes assisted dispersive solid phase extraction of nerve agents and their markers from muddy water.Talanta 2011;86:248-55.
[11]Zhang Z,Kong J.Novel magnetic Fe3O4@C nanoparticles as adsorbents for removal of organic dyes from aqueous solution.J Hazard Mater2011;193:325-9.
[12]Liu ZG,Zhang FS,Sasai R.Arsenate removal from water using Fe3O4-loaded activated carbon prepared from waste biomass.Chem Eng J 2010;160(1):57-62.
[13]Yang N,Zhu SM,Zhang D,Xu S.Synthesis and properties of magnetic Fe3O4-activated carbon nanocomposite particles for dye removal.Mater Lett 2008;62(4-5):645-7.
[14]Zhang J,Xie Q,Liu J,Yang MS,Yao X.Role of Ni(NO3)2in the preparation of a magnetic coal-based activated carbon.Min Sci Technol 2011;21(4):599-603.
[15]Ao YH,Xu JJ,Fu DG,Yuan CW.A simple route for the preparation of anatase titania-coated magnetic porous carbons with enhanced photocatalytic activity.Carbon 2008;46(4):596-603.
[16]Yang MS,Xie Q,Zhang J,Liu J,Wang Y,Zhang XL,et al.Effects of coal rank,Fe3O4amounts and activation temperature on the preparation and characteristics of magnetic activated carbon.Min Sci Technol 2010;20(6):872-6.
[17]Ai LH,Huang HY,Chen ZL,Wei X,Jiang J.Activated carbon/CoFe2O4composites:facile synthesis,magnetic performance and their potential application for the removal of malachite green from water.Chem Eng J2010;156(2):243-9.
[18]Ao YH,Xu JJ,Shen XW,Fu DG,Yuan CW.Magnetically separable composite photocatalyst with enhanced photocatalytic activity.J Hazard Mater 2008;160(2-3):295-300.
[19]Wang SH,Zhou SQ.Titania deposited on soft magnetic activated carbon as a magnetically separable photocatalyst with enhanced activity.Appl Surf Sci2010;256(21):6191-8.
[20]Yamashita T,Hayes P.Analysis of XPS spectra of Fe2+and Fe3+ions in oxide materials.Appl Surf Sci 2008;254(8):2441-9.
[21]Hu Z,Srinivasan MP,Ni Y.Novel activation process for preparing highly microporous and mesoporous activated carbons.Carbon 2001;39(6):877-86.
[22]Nowicki P,Pietrzak R,Wachowska H.X-ray photoelectron spectroscopy study of nitrogen-enriched active carbons obtained by ammoxidation and chemical activation of brown and bituminous coals.Energy Fuels 2010;24(2):1197-206.
[23]Yu JL,Tian FJ,Chow MC,McKenzie LJ,Li CZ.Effect of iron on the gasification of Victorian brown coal with steam:enhancement of hydrogen production.Fuel2006;85(2):127-33.
[24]Maahs HG.Crystallite parameter correlations for graphitic carbons.Carbon1969;7(4):509-10.
[25]Gong GZ,Xie Q,Zheng YF,Ye SF,Chen YF.Regulation of pore size distribution in coal-based activated carbon.New Carbon Mater 2009;24(2):141-6.
[26]Grosvenor AP,Kobe BA,Biesinger MC,Mclntyre NS.Investigation of multiplet splitting of Fe 2p XPS spectra and bonding in iron compounds.Surf Interface Anal 2004;36(12):1564-74.
[27]Seo DK,Park SS,Kim YT,Hwang JH,Yu TU.Study of coal pyrolysis by thermogravimetric analysis(TGA)and concentration measurements of the evolved species.J Anal Appl Pyrol 2011;92(1):209-16.
[28]Huffman GP,Huggins FE,Dunmyre GR.Investigation of the high-temperature behaviour of coal ash in reducing and oxidizing atmospheres.Fuel 1981;60(7):585-97.
[29]Yamashita H,Ohtsuka Y,Yoshida S,Tomita A.Local structures of metals dispersed on coal.1.Change of local structure of iron species on brown coal during heat treatment.Energy Fuels 1989;3(6):686-92.
[30]Hermann G,Huttinger KJ.Mechanism of iron-catalyzed water vapour gasification of carbon.Carbon 1986;24(4):429-35.
[31]Li J,Li BW,Zhang BW.Microwave carbothermic reduction from Fe2O3to Fe3O4powders.J Univ Sci Technol Beijing 2011;33(9):1127-32.
[32]Marcilla A,Asensio M,Gullon MI.Influence of the carbonization heating rate on the physical properties of activated carbons from a sub-bituminous coal.Carbon 1996;34(4):449-56.
[2]Pietrzak R,Wachowska H,Nowicki P,Babel K.Preparation of modified active carbon from brown coal by ammoxidation.Fuel Process Technol 2007;88(4):409-15.
[3]Ariyadejwanich P,Tanthapanichakoon W,Nakagawa K,Mukai SR,Tamon H.Preparation and characterization of mesoporous activated carbon from waste tires.Carbon 2003;41(1):157-64.
[4]Tang L,Zhan L,Yang GZ,Yang JH,Wang YL,Qiao WM,et al.Preparation of mesoporous carbon microsphere/activated carbon composite for electric double-layer capacitors.New Carbon Mater 2011;26(3):237-40.
[5]Hu Z,Srinivasan MP.Mesoporous high-surface-area activated carbon.Micropor Mesopor Mater 2001;43(3):267-75.
[6]Nowicki P,Pietrzak R,Wachowska H.Comparison of physicochemical properties of nitrogen-enriched activated carbons prepared by physical and chemical activation of brown coal.Energy Fuels 2008;22(6):4133-8.
[7]Lin HK,Hill EM,Oleson JL.Recovering gold from carbon fines by a gold transfer process.Miner Metall Process 2003;20(1):47-51.
[8]Oliveira LCA,Rios R,Fabris JD,Garg V,Sapag K,Lago RM.Activated carbon/iron oxide magnetic composites for the adsorption of contaminants in water.Carbon 2002;40(12):2177-83.
[9]Zhu HY,Jiang R,Xiao L,Zeng GM.Preparation,characterization,adsorption kinetics and thermodynamics of novel magnetic chitosan enwrapping nanosized c-Fe2O3and multi-walled carbon nanotubes with enhanced adsorption properties for methyl orange.Bioresour Technol 2010;101(14):5063-9.
[10]Pardasani D,Kanaujia PK,Purohit AK,Shrivastava AR,Dubey DK.Magnetic multi-walled carbon nanotubes assisted dispersive solid phase extraction of nerve agents and their markers from muddy water.Talanta 2011;86:248-55.
[11]Zhang Z,Kong J.Novel magnetic Fe3O4@C nanoparticles as adsorbents for removal of organic dyes from aqueous solution.J Hazard Mater2011;193:325-9.
[12]Liu ZG,Zhang FS,Sasai R.Arsenate removal from water using Fe3O4-loaded activated carbon prepared from waste biomass.Chem Eng J 2010;160(1):57-62.
[13]Yang N,Zhu SM,Zhang D,Xu S.Synthesis and properties of magnetic Fe3O4-activated carbon nanocomposite particles for dye removal.Mater Lett 2008;62(4-5):645-7.
[14]Zhang J,Xie Q,Liu J,Yang MS,Yao X.Role of Ni(NO3)2in the preparation of a magnetic coal-based activated carbon.Min Sci Technol 2011;21(4):599-603.
[15]Ao YH,Xu JJ,Fu DG,Yuan CW.A simple route for the preparation of anatase titania-coated magnetic porous carbons with enhanced photocatalytic activity.Carbon 2008;46(4):596-603.
[16]Yang MS,Xie Q,Zhang J,Liu J,Wang Y,Zhang XL,et al.Effects of coal rank,Fe3O4amounts and activation temperature on the preparation and characteristics of magnetic activated carbon.Min Sci Technol 2010;20(6):872-6.
[17]Ai LH,Huang HY,Chen ZL,Wei X,Jiang J.Activated carbon/CoFe2O4composites:facile synthesis,magnetic performance and their potential application for the removal of malachite green from water.Chem Eng J2010;156(2):243-9.
[18]Ao YH,Xu JJ,Shen XW,Fu DG,Yuan CW.Magnetically separable composite photocatalyst with enhanced photocatalytic activity.J Hazard Mater 2008;160(2-3):295-300.
[19]Wang SH,Zhou SQ.Titania deposited on soft magnetic activated carbon as a magnetically separable photocatalyst with enhanced activity.Appl Surf Sci2010;256(21):6191-8.
[20]Yamashita T,Hayes P.Analysis of XPS spectra of Fe2+and Fe3+ions in oxide materials.Appl Surf Sci 2008;254(8):2441-9.
[21]Hu Z,Srinivasan MP,Ni Y.Novel activation process for preparing highly microporous and mesoporous activated carbons.Carbon 2001;39(6):877-86.
[22]Nowicki P,Pietrzak R,Wachowska H.X-ray photoelectron spectroscopy study of nitrogen-enriched active carbons obtained by ammoxidation and chemical activation of brown and bituminous coals.Energy Fuels 2010;24(2):1197-206.
[23]Yu JL,Tian FJ,Chow MC,McKenzie LJ,Li CZ.Effect of iron on the gasification of Victorian brown coal with steam:enhancement of hydrogen production.Fuel2006;85(2):127-33.
[24]Maahs HG.Crystallite parameter correlations for graphitic carbons.Carbon1969;7(4):509-10.
[25]Gong GZ,Xie Q,Zheng YF,Ye SF,Chen YF.Regulation of pore size distribution in coal-based activated carbon.New Carbon Mater 2009;24(2):141-6.
[26]Grosvenor AP,Kobe BA,Biesinger MC,Mclntyre NS.Investigation of multiplet splitting of Fe 2p XPS spectra and bonding in iron compounds.Surf Interface Anal 2004;36(12):1564-74.
[27]Seo DK,Park SS,Kim YT,Hwang JH,Yu TU.Study of coal pyrolysis by thermogravimetric analysis(TGA)and concentration measurements of the evolved species.J Anal Appl Pyrol 2011;92(1):209-16.
[28]Huffman GP,Huggins FE,Dunmyre GR.Investigation of the high-temperature behaviour of coal ash in reducing and oxidizing atmospheres.Fuel 1981;60(7):585-97.
[29]Yamashita H,Ohtsuka Y,Yoshida S,Tomita A.Local structures of metals dispersed on coal.1.Change of local structure of iron species on brown coal during heat treatment.Energy Fuels 1989;3(6):686-92.
[30]Hermann G,Huttinger KJ.Mechanism of iron-catalyzed water vapour gasification of carbon.Carbon 1986;24(4):429-35.
[31]Li J,Li BW,Zhang BW.Microwave carbothermic reduction from Fe2O3to Fe3O4powders.J Univ Sci Technol Beijing 2011;33(9):1127-32.
[32]Marcilla A,Asensio M,Gullon MI.Influence of the carbonization heating rate on the physical properties of activated carbons from a sub-bituminous coal.Carbon 1996;34(4):449-56.