磁性生物炭的制备、表征及对磷的吸附特性
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摘要
处理成本高、分离难度大是当前湖库等相对封闭水体磷治理工程中的主要问题。为此,以廉价农林废弃物花生壳为主要前驱物与Fe_3O_4纳米颗粒复合制备一种低成本、可磁分离的磁性生物炭吸附剂,研究了热解温度(400℃、500℃、600℃)、溶液pH值、阴离子(Cl~-和SO_4~(2-))共存等因素对复合材料吸附性能的影响。结果表明,复合后的磁性生物炭最大吸附量相比复合前提升了3~5倍。动力学数据拟合结果表明,拟二级动力学方程能较好地拟合吸附过程。磁性生物炭的零电荷点(均<7.5)与前驱物的热解终温在试验范围内呈现明显的正相关,表明引入Fe_3O_4后可明显增加磁性生物炭表面电荷,进而有效提升吸附性能。此外,阴离子共存试验表明,磁性生物炭对磷具有较好的选择性。
The objective of this article is to discuss how to prepare a kind of inexpensive,magnetically separable adsorbent for phosphate,known as the biochar-based magnetic composites(short for BMCs).The ready-made BMCs can be synthesized from the magnetic iron-oxide(Fe_3O_4)nanoparticles and the biochars(BCs)derived from the cheap and ordinary farming wastes,such as the peanut shells through chemical co-precipitation processing.As is well known,it is difficult to separate the adsorbent from the phosphorus-contaminated water,particularly from the enclosed or semi-enclosed waters,for instance,lakes and reservoirs,which makes it highly expensive for the treatment due to two main factors,that is,the limited application of the adsorption method and the physico-chemical properties of BMCs and the BCs response to the pyrolysis temperature,which involve complicated scanning of the electron microscope(SEM),the X-ray diffraction(XRD),the Fourier transform infrared spectroscopy(FTIR)and the point of zero charge(PZC)measurement.In addition,it is also necessary to conduct a batch of experiments to assess the effects of the pyrolysis temperature(400℃,500℃and 600℃),the p H value of the solution and the coexistant anions(Cland SO42-)on the performance of the phosphate removal when the BMCs and BCs are to be used,respectively.The result of the physico-chemical characterization indicates that the morphological state of BMCs tends to be significantly different from that of BCs'surface area whereas the point of zero charges tends to be positively related to the pyrolysis temperature to a certain extent.What is more,the effect of BMCs on the phosphate removal proves higher than that on BCs for a factor of 3-5 probably because the process involves metal oxide at a higher point of zero charge(for example,the point of zero charge of Fe_3O_4is about 9),which can significantly promote the surface charge capacities of BMCs,and,therefore,can contribute significantly to the phosphate removal.The removal of phosphate can also be controlled mainly by the chemical actions,for which the adsorption kinetics of BMCs and BCs is usually described by pseudo-second kinetic equation better than with other methods.Besides,higher adsorptive capacity of the adsorbent can also be found in the product of BMC synthesized from the biochar produced at higher pyrolysis temperature at the rate of 22.32 mg/g as can be predicted by Langmuir model.And,finally,it is also necessary to point it out that BMCs is in a position to display perfect selectivity on phosphate in case that there exist Cl~-,SO_4~(2-) and H_2PO4_- in the solution.
The objective of this article is to discuss how to prepare a kind of inexpensive,magnetically separable adsorbent for phosphate,known as the biochar-based magnetic composites(short for BMCs).The ready-made BMCs can be synthesized from the magnetic iron-oxide(Fe_3O_4)nanoparticles and the biochars(BCs)derived from the cheap and ordinary farming wastes,such as the peanut shells through chemical co-precipitation processing.As is well known,it is difficult to separate the adsorbent from the phosphorus-contaminated water,particularly from the enclosed or semi-enclosed waters,for instance,lakes and reservoirs,which makes it highly expensive for the treatment due to two main factors,that is,the limited application of the adsorption method and the physico-chemical properties of BMCs and the BCs response to the pyrolysis temperature,which involve complicated scanning of the electron microscope(SEM),the X-ray diffraction(XRD),the Fourier transform infrared spectroscopy(FTIR)and the point of zero charge(PZC)measurement.In addition,it is also necessary to conduct a batch of experiments to assess the effects of the pyrolysis temperature(400℃,500℃and 600℃),the p H value of the solution and the coexistant anions(Cland SO42-)on the performance of the phosphate removal when the BMCs and BCs are to be used,respectively.The result of the physico-chemical characterization indicates that the morphological state of BMCs tends to be significantly different from that of BCs'surface area whereas the point of zero charges tends to be positively related to the pyrolysis temperature to a certain extent.What is more,the effect of BMCs on the phosphate removal proves higher than that on BCs for a factor of 3-5 probably because the process involves metal oxide at a higher point of zero charge(for example,the point of zero charge of Fe_3O_4is about 9),which can significantly promote the surface charge capacities of BMCs,and,therefore,can contribute significantly to the phosphate removal.The removal of phosphate can also be controlled mainly by the chemical actions,for which the adsorption kinetics of BMCs and BCs is usually described by pseudo-second kinetic equation better than with other methods.Besides,higher adsorptive capacity of the adsorbent can also be found in the product of BMC synthesized from the biochar produced at higher pyrolysis temperature at the rate of 22.32 mg/g as can be predicted by Langmuir model.And,finally,it is also necessary to point it out that BMCs is in a position to display perfect selectivity on phosphate in case that there exist Cl~-,SO_4~(2-) and H_2PO4_- in the solution.
引文
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[12]TONG Jing(童婧),YANG Zhaohui(杨朝晖),ZENG Guangming(曾光明),et al.Preparation of hydroxyl-iron-zirconium modified activated carbon fieber and its phosphate removal performance[J].Chinese Journal of Environmental Engineering(环境工程学报),2016,10(6):2881-2888.
[13]CHEN X,CHEN G,CHEN L,et al.Adsorption of copper and zinc by biochars produced from pyrolysis of hardwood and corn straw in aqueous solution[J].Bioresource Technology,2011,102(19):8877-8884.
[14]JIANG Xutao(蒋旭涛),CHI Jie(迟杰).Phosphorus adsorption by and forms in Fe-modified biochar[J].Journal of Agro-Environmental Science(农业环境科学学报),2014,33(9):1817-1822.
[15]BOURIKAS K,KORDULIS C,LYCOURGHIOTIS A.Differential potentiometric titration:development of a methodology for determining the point of zero charge of metal(hydr)oxides by one titration curve[J].Environmental Science&Technology,2005,39(11):4100-4108.
[16]YANG Y,CHEN J P.Key factors for optimum performance in phosphate removal from contaminated water by a Fe-Mg-La tri-metal composite sorbent[J].Journal of Colloid&Interface Science,2015,445:303-311.
[17]AHMAD M,LEE S S,DOU X,et al.Effects of pyrolysis temperature on soybean stover-and peanut shell-derived biochar properties and TCE adsorption in water[J].Bioresource Technology,2012,118(8):536-544.
[18]KAMEYAMA K,MIYAMOTO T,SHIONO T,et al.Influence of sugarcane bagasse-derived biochar application on nitrate leaching in calcaric dark red soil[J].Journal of Environmental Quality,2012,41(4):1131-1137.
[19]WANG Zhanghong(王章鸿),GUO Haiyan(郭海艳),SHEN Fei(沈飞),et al.Effects of pyrolysis conditions on the properties of biochar and its adsorption to N and P from solution[J].Acta Scientiae Circumstantiae(环境科学学报),2015,35(9):2805-2812.
[20]KOSMULSKI M.Surface charging and points of zero charge[M].New York:American Chemical Society,2009.
[21]GONG C,CHEN D,JIAO X,et al.Continuous hollowα-Fe2O3andα-Fe fibers prepared by the sol-gel method[J].Journal of Materials Chemistry,2002,12(6):1844-1847.
[22]L Honghong(吕宏虹),GONG Yanyan(宫艳艳),TANG Jingchun(唐景春),et al.Advances in preparation and applicaitions of biochar and its composites[J].Journal of Agro-Environment Science(农业环境科学学报),2015,34(8):1429-1440.
[23]YAN L G,XU Y Y,YU H Q,et al.Adsorption of phosphate from aqueous solution by hydroxy-aluminum,hydroxy-iron and hydroxyiron-aluminum pillared bentonites[J].Journal of Hazardous Materials,2010,179(3):244-250.
[24]MA Fengfeng(马锋锋),ZHAO Baowei(赵保卫),ZHONGJinkui(钟金魁),et al.Characteristics phosphate adsorption onto biochars derived from dairy manure and its influencing factors[J].China Environmental Science(中国环境科学),2015,35(4):1156-1163.
[25]CHITRAKAR R,TEZUKA S,SONODA A,et al.Selective adsorption of phosphate from seawater and wastewater by amorphous zirconium hydroxide[J].Journal of Colloid&Interface Science,2006,297(2):426-433.
[26]YAO Y,GAO B,INYANG M,et al.Removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings[J].Journal of Hazardous Materials,2011,190(3):501-507.
[2]ZHANG M,ZHENG P,ABBAS G,et al.Partitionable-space enhanced coagulation(PEC)reactor and its working mechanism:a new prospective chemical technology for phosphorus pollution control[J].Water Research,2014,49(2):426-433.
[3]ZUTHI M F,GUO W S,NGO H H,et al.Enhanced biological phosphorus removal and its modeling for the activated sludge and membrane bioreactor processes[J].Bioresource Technology,2013,139(13):363-374.
[4]YAN L,KONG L,QU Z,et al.Magnetic biochar decorated with Zn S nanocrytals for Pb(II)removal[J].Acs Sustainable Chemistry&Engineering,2015,3(1):125-132.
[5]ALTMANN J,REHFELD D,TRADER K,et al.Combination of granular activated carbon adsorption and deep-bed filtration as a single advanced wastewater treatment step for organic micropollutant and phosphorus removal[J].Water Research,2016,92:131-139.
[6]CHEN T H,WANG J Z,WANG J,et al.Phosphorus removal from aqueous solutions containing low concentration of phosphate using pyrite calcinate sorbent[J].Environmental Science and Technology,2015,12(3):885-892.
[7]SEIFRITZ W.Should we store carbon in charcoal[J].International Journal of Hydrogen Energy,1993,18(5):405-407.
[8]LEHMANN J.Black is the new green[J].Nature,2006,442(10):624-626.
[9]YAO Y,GAO B,ZHANG M,et al.Effect of biochar amendment on sorption and leaching of nitrate,ammonium,and phosphate in a sandy soil[J].Chemosphere,2012,89(11):1467-1471.
[10]YAO Y,GAO B,CHEN J,et al.Engineered biochar reclaiming phosphate from aqueous solutions:mechanisms and potential application as a slow-release fertilizer[J].Environmental Science&Technology,2013,47(15):8700-8708.
[11]DAI L,WU B,TAN F,et al.Engineered hydrochar composites for phosphorus removal/recovery:lanthanum doped hydrochar prepared by hydrothermal carbonization of lanthanum pretreated rice straw[J].Bioresource Technology,2014,161(3):327-332.
[12]TONG Jing(童婧),YANG Zhaohui(杨朝晖),ZENG Guangming(曾光明),et al.Preparation of hydroxyl-iron-zirconium modified activated carbon fieber and its phosphate removal performance[J].Chinese Journal of Environmental Engineering(环境工程学报),2016,10(6):2881-2888.
[13]CHEN X,CHEN G,CHEN L,et al.Adsorption of copper and zinc by biochars produced from pyrolysis of hardwood and corn straw in aqueous solution[J].Bioresource Technology,2011,102(19):8877-8884.
[14]JIANG Xutao(蒋旭涛),CHI Jie(迟杰).Phosphorus adsorption by and forms in Fe-modified biochar[J].Journal of Agro-Environmental Science(农业环境科学学报),2014,33(9):1817-1822.
[15]BOURIKAS K,KORDULIS C,LYCOURGHIOTIS A.Differential potentiometric titration:development of a methodology for determining the point of zero charge of metal(hydr)oxides by one titration curve[J].Environmental Science&Technology,2005,39(11):4100-4108.
[16]YANG Y,CHEN J P.Key factors for optimum performance in phosphate removal from contaminated water by a Fe-Mg-La tri-metal composite sorbent[J].Journal of Colloid&Interface Science,2015,445:303-311.
[17]AHMAD M,LEE S S,DOU X,et al.Effects of pyrolysis temperature on soybean stover-and peanut shell-derived biochar properties and TCE adsorption in water[J].Bioresource Technology,2012,118(8):536-544.
[18]KAMEYAMA K,MIYAMOTO T,SHIONO T,et al.Influence of sugarcane bagasse-derived biochar application on nitrate leaching in calcaric dark red soil[J].Journal of Environmental Quality,2012,41(4):1131-1137.
[19]WANG Zhanghong(王章鸿),GUO Haiyan(郭海艳),SHEN Fei(沈飞),et al.Effects of pyrolysis conditions on the properties of biochar and its adsorption to N and P from solution[J].Acta Scientiae Circumstantiae(环境科学学报),2015,35(9):2805-2812.
[20]KOSMULSKI M.Surface charging and points of zero charge[M].New York:American Chemical Society,2009.
[21]GONG C,CHEN D,JIAO X,et al.Continuous hollowα-Fe2O3andα-Fe fibers prepared by the sol-gel method[J].Journal of Materials Chemistry,2002,12(6):1844-1847.
[22]L Honghong(吕宏虹),GONG Yanyan(宫艳艳),TANG Jingchun(唐景春),et al.Advances in preparation and applicaitions of biochar and its composites[J].Journal of Agro-Environment Science(农业环境科学学报),2015,34(8):1429-1440.
[23]YAN L G,XU Y Y,YU H Q,et al.Adsorption of phosphate from aqueous solution by hydroxy-aluminum,hydroxy-iron and hydroxyiron-aluminum pillared bentonites[J].Journal of Hazardous Materials,2010,179(3):244-250.
[24]MA Fengfeng(马锋锋),ZHAO Baowei(赵保卫),ZHONGJinkui(钟金魁),et al.Characteristics phosphate adsorption onto biochars derived from dairy manure and its influencing factors[J].China Environmental Science(中国环境科学),2015,35(4):1156-1163.
[25]CHITRAKAR R,TEZUKA S,SONODA A,et al.Selective adsorption of phosphate from seawater and wastewater by amorphous zirconium hydroxide[J].Journal of Colloid&Interface Science,2006,297(2):426-433.
[26]YAO Y,GAO B,INYANG M,et al.Removal of phosphate from aqueous solution by biochar derived from anaerobically digested sugar beet tailings[J].Journal of Hazardous Materials,2011,190(3):501-507.