凹凸棒黏土负载纳米TiO_2-Fe_3O_4吸附剂的制备及Cr(Ⅵ)的脱除
|
摘要
采用溶胶-凝胶法、一锅反应法制备了负载纳米TiO_2和Fe_3O_4的凹凸棒黏土(TiO_2-Fe_3O_4-ATP)吸附剂,并进行了模拟废水中Cr(Ⅵ)的吸附及脱附性能的研究。通过扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)和EDS等分析方法对ATP负载纳米TiO_2-Fe_3O_4前后结构进行了表征,考察了物料配比及吸附时间、pH值、温度、投加量和初始质量浓度对Cr(Ⅵ)吸附率的影响。结果表明,吸附剂在Ti元素含量与负载总量的摩尔比为3∶4时吸附效果最佳。当吸附剂质量为0. 6 g,Cr(Ⅵ)离子初始质量浓度小于0. 8 mg/L时,pH=6,温度20℃,吸附剂对Cr(Ⅵ)的吸附率为79. 8%。TiO_2-Fe_3O_4-ATP吸附剂对Cr(Ⅵ)离子吸附满足Freundlich模型。在20～40℃条件下,吸附过程ΔG <0、ΔS=-43. 55 J/(mol·K)、ΔH=-14. 36 k J/mol,表明该吸附是个自发、熵减、放热的过程。吸附过程符合准二级动力学模型,吸附速率控制步骤以表面化学反应为主。TiO_2-Fe_3O_4-ATP吸附剂在循环使用4次后,吸附率仍能达到65%以上。
Attapulgite clay( ATP) supported nano TiO_2-Fe_3O_4( TiO_2-Fe_3O_4-ATP) adsorbents were prepared by sol-gel method in one-pot,and its adsorption and desorption properties of Cr( Ⅵ) in simulated wastewater were studied. The structure and contents of the adsorbent were characterized by scanning electron microscopy( SEM),X-ray diffraction( XRD),Fourier transform infrared spectrometer( FT-IR) and EDS before and after nano TiO_2-Fe_3O_4 loading,The effects of the ratio of reactants,adsorption time,pH value,temperature,dosage and initial concentration on the adsorption rate of Cr( Ⅵ) were studied. The best performance of the adsorbents was observed when the molar fraction of Ti in the total loading is 75%. The attapulgite adsorbent loaded with nano TiO_2 and Fe_3O_4 has better adsorption effect on the removal of Cr( Ⅵ) when the mass of adsorbent is 0. 6 g. When the initial concentration of Cr( Ⅵ) is less than 0. 8 mg/L and the pH value is 6 at20 ℃,the adsorption rate of Cr( Ⅵ) reached 79. 8%. The adsorption of Cr( Ⅵ) by TiO_2-Fe_3O_4-ATP can be described by Freundlich equation. At 20 ～ 40 ℃,the free energy( ΔG),enthalpy( ΔH) and entropy( ΔS)changes of the adsorption process were calculated. The results show that ΔG < 0,ΔS =-43. 55 J/( mol·K),ΔH =-14. 36 kJ/mol,indicating that the adsorption is spontaneous,exothermic and entropy reduction.Pseudo-first-order kinetic model,pseudo-second-order kinetic model and shell progressive model were studied for the kinetic data. The result shows that the adsorption process fits the quasi-second-order kinetic model.The rate control step of adsorption is mainly surface chemical reaction. The adsorption rate of TiO_2-Fe_3O_4-ATP adsorbent can reach more than 65% after 4 times of recycling.
Attapulgite clay( ATP) supported nano TiO_2-Fe_3O_4( TiO_2-Fe_3O_4-ATP) adsorbents were prepared by sol-gel method in one-pot,and its adsorption and desorption properties of Cr( Ⅵ) in simulated wastewater were studied. The structure and contents of the adsorbent were characterized by scanning electron microscopy( SEM),X-ray diffraction( XRD),Fourier transform infrared spectrometer( FT-IR) and EDS before and after nano TiO_2-Fe_3O_4 loading,The effects of the ratio of reactants,adsorption time,pH value,temperature,dosage and initial concentration on the adsorption rate of Cr( Ⅵ) were studied. The best performance of the adsorbents was observed when the molar fraction of Ti in the total loading is 75%. The attapulgite adsorbent loaded with nano TiO_2 and Fe_3O_4 has better adsorption effect on the removal of Cr( Ⅵ) when the mass of adsorbent is 0. 6 g. When the initial concentration of Cr( Ⅵ) is less than 0. 8 mg/L and the pH value is 6 at20 ℃,the adsorption rate of Cr( Ⅵ) reached 79. 8%. The adsorption of Cr( Ⅵ) by TiO_2-Fe_3O_4-ATP can be described by Freundlich equation. At 20 ～ 40 ℃,the free energy( ΔG),enthalpy( ΔH) and entropy( ΔS)changes of the adsorption process were calculated. The results show that ΔG < 0,ΔS =-43. 55 J/( mol·K),ΔH =-14. 36 kJ/mol,indicating that the adsorption is spontaneous,exothermic and entropy reduction.Pseudo-first-order kinetic model,pseudo-second-order kinetic model and shell progressive model were studied for the kinetic data. The result shows that the adsorption process fits the quasi-second-order kinetic model.The rate control step of adsorption is mainly surface chemical reaction. The adsorption rate of TiO_2-Fe_3O_4-ATP adsorbent can reach more than 65% after 4 times of recycling.
引文
[1]Dilek Duranoglu,Andrzej W Trochimczuk,Ulker Beker. Kinetics and Thermodynamics of Hexavalent Chromium Adsorption onto Activated Carbon Derived from Acrylonitrile-Divinylbenzene Copolymer[J]. Chem Eng J,2004,99(2):193-202.
[2]Cavendish H,Planta J. Adsorption of Nitrate and Cr(Ⅵ)by Cationic Polymer-Modified Granular Activated Carbon[J].Chem Eng J,2011,175(1):298-305.
[3]Li L,Fan L,Sun M,et al. Adsorbent for Chromium Removal Based on Graphene Oxide Functionalized with Magnetic Cyclodextrin-Chitosan[J]. Colloids Surf B,2013,58(7):169-175.
[4]WANG Aiqin,WANG Wenbo,ZHENG Yian,et al. The Dissociation of Attapulgite and Its Nanofunctional Composites[M].Beijing:Science Press,2014:106-107(in Chinese).王爱勤,王文波,郑易安,等.凹凸棒石棒晶束解离及其纳米功能复合材料[M].北京:科学出版社,2014:106-107.
[5]Chen H,Zhao Y,Wang A. Removal of Cu(Ⅱ)from Aqueous Solution by Adsorption onto Acid-Activated Palygorskite[J].J Hazard Mater,2007,149(2):346-354.
[6]Zhang J,Chen H,Wang A. Study on Superabsorbent Composite.Ⅲ. Swelling Behaviors of Polyacrylamide/Attapulgite Composite Based on Acidified Attapulgite and Organo-Attapulgite[J]. Eur Polym J,2005,41(10):2434-2442.
[7]LONG Xiaoyan. Effects and Mechanisms for Fe/Ti Modification of Activated Carbon and Its Arsenic Removal from Water[D]. Huazhong Agricultural University,2012(in Chinese).龙小燕.活性炭负载Fe/Ti改性及去除水体砷的效果和机理研究[D].华中农业大学,2012.
[8]LIU Yan,LIANG Pei,GUO Li,et al. Study on the Adsorption Behavior of Heavy Metal Ions on Nanometer Ti O2Supported on Silica Gel[J]. J Chem Ind Eng,2005,63(4):312-316(in Chinese).刘艳,梁沛,郭丽,等.负载型纳米二氧化钛对重金属离子吸附性能的研究[J].化工学报,2005,63(4):312-316.
[9]LI Xiazhang,YAO Chao,LU Xiaowang,et al. Ti O2/Attapulgite Nanocomposite as Photocatalyst:Impact of Phase Transition[J]. Sci Adv Mater,2015,7(7):1400-1405.
[10]Li X L,Qi Y X,Li Y F,et al. Novel Magnetic Beads Based on Sodium Alginate Gel Crosslinked by Zirconium(Ⅳ)and Their Effective Removal for Pb2+in Aqueous Solutions by Using a Batch and Continuous Systems[J]. Bioresour Technol,2013,142:611-619.
[11]Xie M J,Zeng L X,Zhang Q Y,et al. Synthesis and Adsorption Behavior of Magnetic Microspheres Based on Chitosan/Organic Rectorite for Low-concentration Heavy Metal Removal[J]. J Alloys Comd,2015,647:892-905.
[12]GUO Binbin,OUYANG Jing,YANG Huaming. Adsorption Performance to Methylene Blue by Nano-Fe3O4Assembled in Lumen of Halloysite Nanotubes[J]. J Chinese Ceram Soc,2016,44(11):1655-1661(in Chinese).郭斌斌,欧阳静,杨华明.埃洛石管内负载纳米四氧化三铁复合材料对亚甲基蓝的吸附性能[J].硅酸盐学报,2016,44(11):1655-1661.
[13]SUN Linlin,ZHOU Yehong,WANG Fei,et al. Adsorption Properties of Carboxymethyl-β-cyclodextrin Functionalized Ferroferric Oxide Magnetic Nanocomposites on Rhodamine B[J]. Chinese J Appl Chem,2015,32(1):110-117(in Chinese).孙琳琳,周叶红,王斐,等.羧甲基-β-环糊精功能化的四氧化三铁磁性纳米复合物对罗丹明B的吸附性能[J].应用化学,2015,32(1):110-117.
[14]Liu Y M,Ju X J,Xin Y,et al. A Novel Smart Microsphere with Magnetic Core and Ion-recognizable Shell for Pb2+Adsorption and Separation[J]. ACS Appl Mater Interfaces,2014,6(12):9530-9542.
[15] Zhang J H,Zhang L L,Zhou S Y. Magnetically Separable Attapulgite-TiO2-FexOyComposites with Superior Activity Towrds Photodegradation of Methyl Orange under Visible Light Radiation[J]. J Ind Eng Chem,2014,20:3884-3889.
[16]Jafari Z,Mokhtarian N,Hosseinzadeh G,et al. Ag/Ti O2/freeze-dried Graphene Nanocomposite as a High Performance Photocatalyst under Visible Light Irradiation[J]. J Energ Chem,2016,25(3):393-402.
[17]LI Feng,LI Taohai. Systhesis and Photocatalytic Property of H0. 8Ni0. 4Ti1. 6O4/Ti O2Layered Nancomposite[J]. J Natl Sci Xiangtan Univ,2009,(2):96-98(in Chinese).李凤,李涛海. H0. 8Ni0. 4Ti1. 6O4/Ti O2纳米复合材料的合成及光催化性质[J].湘潭大学自然科学学报,2009,(2):96-98.
[18]LI Jingping,ZHENG Lichun,CHEN Feng,et al. Study on the Adsorption Property of the Residue after Humid Acid Extraction to Cu2+[J]. Chem Bull,2010,73(8):719-723(in Chinese).李静萍,郑李纯,陈峰,等.提取腐植酸后的残渣对Cu2+的吸附性能研究[J].化学通报,2010,73(8):719-723.
[19]ZENG Xue,LUO Xuegang,ZHOU Jian. Adsorption of Fluorion onto Hydrolyzed Leather Waste Impregnated with Zirconium(Ⅵ)[J]. J Chem Ind Eng,2016,67(4):1368-1377(in Chinese).曾雪,罗学刚,周建.负载Zr(Ⅳ)的水解废弃皮革对氟离子的吸附性能[J].化工学报,2016,67(4):1368-1377.
[20]YANG Jiajing. Study on the Performance for Adsorbing Heavy Metal Ions by the Organic Attapulgite[D]. Lanzhou:Lanzhou Jiaotong University,2015(in Chinese).杨佳静.有机改性凹凸棒石黏土的制备及其吸附性能研究[D].兰州:兰州交通大学,2015.
[21]WANG Guan. Study on the Performance of Heavy Metal Ions Adsorption of Nano Ti O2Loaded Attapulgite[D]. Lanzhou:Lanzhou Jiaotong University,2013(in Chinese).王冠.凹凸棒石黏土负载纳米Ti O2对重金属离子吸附性能研究[D].兰州:兰州交通大学,2013.
[22]Corneio J,Hermosin M C. Structural Alteration of Sepiolite by Dry Grinding[J]. Clay Minerals J,1988,23:391-398.
[23]Gionis V. On the Structure of Palygorskite by Mid-and Near-Infrared Spectroscopy[J]. Am Mineral,2006,91:1125-1133.
[24]Frost R L,Locos O B,Ruan H,et al. Near-infrared and Mid-infrared Spectroscopic Study of Sepiolites and Palygorskites[J]. Vib Spectrosc,2001,27:1-13.
[2]Cavendish H,Planta J. Adsorption of Nitrate and Cr(Ⅵ)by Cationic Polymer-Modified Granular Activated Carbon[J].Chem Eng J,2011,175(1):298-305.
[3]Li L,Fan L,Sun M,et al. Adsorbent for Chromium Removal Based on Graphene Oxide Functionalized with Magnetic Cyclodextrin-Chitosan[J]. Colloids Surf B,2013,58(7):169-175.
[4]WANG Aiqin,WANG Wenbo,ZHENG Yian,et al. The Dissociation of Attapulgite and Its Nanofunctional Composites[M].Beijing:Science Press,2014:106-107(in Chinese).王爱勤,王文波,郑易安,等.凹凸棒石棒晶束解离及其纳米功能复合材料[M].北京:科学出版社,2014:106-107.
[5]Chen H,Zhao Y,Wang A. Removal of Cu(Ⅱ)from Aqueous Solution by Adsorption onto Acid-Activated Palygorskite[J].J Hazard Mater,2007,149(2):346-354.
[6]Zhang J,Chen H,Wang A. Study on Superabsorbent Composite.Ⅲ. Swelling Behaviors of Polyacrylamide/Attapulgite Composite Based on Acidified Attapulgite and Organo-Attapulgite[J]. Eur Polym J,2005,41(10):2434-2442.
[7]LONG Xiaoyan. Effects and Mechanisms for Fe/Ti Modification of Activated Carbon and Its Arsenic Removal from Water[D]. Huazhong Agricultural University,2012(in Chinese).龙小燕.活性炭负载Fe/Ti改性及去除水体砷的效果和机理研究[D].华中农业大学,2012.
[8]LIU Yan,LIANG Pei,GUO Li,et al. Study on the Adsorption Behavior of Heavy Metal Ions on Nanometer Ti O2Supported on Silica Gel[J]. J Chem Ind Eng,2005,63(4):312-316(in Chinese).刘艳,梁沛,郭丽,等.负载型纳米二氧化钛对重金属离子吸附性能的研究[J].化工学报,2005,63(4):312-316.
[9]LI Xiazhang,YAO Chao,LU Xiaowang,et al. Ti O2/Attapulgite Nanocomposite as Photocatalyst:Impact of Phase Transition[J]. Sci Adv Mater,2015,7(7):1400-1405.
[10]Li X L,Qi Y X,Li Y F,et al. Novel Magnetic Beads Based on Sodium Alginate Gel Crosslinked by Zirconium(Ⅳ)and Their Effective Removal for Pb2+in Aqueous Solutions by Using a Batch and Continuous Systems[J]. Bioresour Technol,2013,142:611-619.
[11]Xie M J,Zeng L X,Zhang Q Y,et al. Synthesis and Adsorption Behavior of Magnetic Microspheres Based on Chitosan/Organic Rectorite for Low-concentration Heavy Metal Removal[J]. J Alloys Comd,2015,647:892-905.
[12]GUO Binbin,OUYANG Jing,YANG Huaming. Adsorption Performance to Methylene Blue by Nano-Fe3O4Assembled in Lumen of Halloysite Nanotubes[J]. J Chinese Ceram Soc,2016,44(11):1655-1661(in Chinese).郭斌斌,欧阳静,杨华明.埃洛石管内负载纳米四氧化三铁复合材料对亚甲基蓝的吸附性能[J].硅酸盐学报,2016,44(11):1655-1661.
[13]SUN Linlin,ZHOU Yehong,WANG Fei,et al. Adsorption Properties of Carboxymethyl-β-cyclodextrin Functionalized Ferroferric Oxide Magnetic Nanocomposites on Rhodamine B[J]. Chinese J Appl Chem,2015,32(1):110-117(in Chinese).孙琳琳,周叶红,王斐,等.羧甲基-β-环糊精功能化的四氧化三铁磁性纳米复合物对罗丹明B的吸附性能[J].应用化学,2015,32(1):110-117.
[14]Liu Y M,Ju X J,Xin Y,et al. A Novel Smart Microsphere with Magnetic Core and Ion-recognizable Shell for Pb2+Adsorption and Separation[J]. ACS Appl Mater Interfaces,2014,6(12):9530-9542.
[15] Zhang J H,Zhang L L,Zhou S Y. Magnetically Separable Attapulgite-TiO2-FexOyComposites with Superior Activity Towrds Photodegradation of Methyl Orange under Visible Light Radiation[J]. J Ind Eng Chem,2014,20:3884-3889.
[16]Jafari Z,Mokhtarian N,Hosseinzadeh G,et al. Ag/Ti O2/freeze-dried Graphene Nanocomposite as a High Performance Photocatalyst under Visible Light Irradiation[J]. J Energ Chem,2016,25(3):393-402.
[17]LI Feng,LI Taohai. Systhesis and Photocatalytic Property of H0. 8Ni0. 4Ti1. 6O4/Ti O2Layered Nancomposite[J]. J Natl Sci Xiangtan Univ,2009,(2):96-98(in Chinese).李凤,李涛海. H0. 8Ni0. 4Ti1. 6O4/Ti O2纳米复合材料的合成及光催化性质[J].湘潭大学自然科学学报,2009,(2):96-98.
[18]LI Jingping,ZHENG Lichun,CHEN Feng,et al. Study on the Adsorption Property of the Residue after Humid Acid Extraction to Cu2+[J]. Chem Bull,2010,73(8):719-723(in Chinese).李静萍,郑李纯,陈峰,等.提取腐植酸后的残渣对Cu2+的吸附性能研究[J].化学通报,2010,73(8):719-723.
[19]ZENG Xue,LUO Xuegang,ZHOU Jian. Adsorption of Fluorion onto Hydrolyzed Leather Waste Impregnated with Zirconium(Ⅵ)[J]. J Chem Ind Eng,2016,67(4):1368-1377(in Chinese).曾雪,罗学刚,周建.负载Zr(Ⅳ)的水解废弃皮革对氟离子的吸附性能[J].化工学报,2016,67(4):1368-1377.
[20]YANG Jiajing. Study on the Performance for Adsorbing Heavy Metal Ions by the Organic Attapulgite[D]. Lanzhou:Lanzhou Jiaotong University,2015(in Chinese).杨佳静.有机改性凹凸棒石黏土的制备及其吸附性能研究[D].兰州:兰州交通大学,2015.
[21]WANG Guan. Study on the Performance of Heavy Metal Ions Adsorption of Nano Ti O2Loaded Attapulgite[D]. Lanzhou:Lanzhou Jiaotong University,2013(in Chinese).王冠.凹凸棒石黏土负载纳米Ti O2对重金属离子吸附性能研究[D].兰州:兰州交通大学,2013.
[22]Corneio J,Hermosin M C. Structural Alteration of Sepiolite by Dry Grinding[J]. Clay Minerals J,1988,23:391-398.
[23]Gionis V. On the Structure of Palygorskite by Mid-and Near-Infrared Spectroscopy[J]. Am Mineral,2006,91:1125-1133.
[24]Frost R L,Locos O B,Ruan H,et al. Near-infrared and Mid-infrared Spectroscopic Study of Sepiolites and Palygorskites[J]. Vib Spectrosc,2001,27:1-13.