磷对镉离子在针铁矿及针铁矿-胡敏酸复合体表面吸附的影响
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摘要
为了探讨磷镉共存条件下镉离子在针铁矿和针铁矿-胡敏酸复合体表面的吸附特征,通过室内合成方法制备针铁矿和针铁矿-胡敏酸复合体,利用等温吸附试验和动力学吸附试验来获取磷酸盐共存时镉离子在针铁矿和复合体表面的吸附规律,并分析pH和离子强度对镉离子吸附的影响。结果表明,胡敏酸在针铁矿表面的吸附包被降低了针铁矿的比表面积和电荷零点,但提高了矿物表面的位点浓度。用Langmuir方程和二级动力学方程描述镉离子在针铁矿和复合体表面的等温吸附和动力学吸附行为,均获得较好的拟合结果。胡敏酸吸附包被形成的复合体对镉离子具有较高的吸附量(X_m,q_e)和吸附强度(K_L);在pH 4. 5条件下随着离子强度的增加针铁矿对镉离子的吸附下降幅度小于复合体,而在pH 6. 5条件下镉离子在复合体表面的吸附随离子强度增加而降低的幅度小于在针铁矿表面。磷酸盐共存和pH的增加均提高镉离子的吸附量和最大理论吸附量;在pH 6. 5条件下,磷酸根的共存增强了镉离子在针铁矿和复合体表面的K_L、吸附速率常数(k)和初始吸附速率(h);同时磷酸根的存在减弱了离子强度增加对镉离子吸附的抑制效应。
The aim of this study is to investigate the adsorption characteristics of cadmium on goethite(G)and humic acid-coated goethite complexes(GH)under the application of phosphate by the isotherm and kinetic adsorption experiments. The effects of pH and ionic strength on cadmium adsorption were also determined. The results show that both the specific surface area and the isoelectric point of humic acid-coated goethite complexes were lower than those of goethite.However,the surface sites density of the complexes coated by humic acid was higher than that of goethite. The Langmuir equation and pseudo-second-order model were applied to describe the isotherm and kinetic adsorption of cadmium on goethite and humic acid-coated goethite complexes,respectively,and the better fitting effects were achieved. The presence of humic acid coated on goethite enhanced the maximum adsorption(X_m,q_e) and the adsorption affinity(K_L) of cadmium.With the increase of ionic strength,the reduction rate of cadmium adsorption on goethite was lower than that on complexes at pH 4. 5,while the reduction rate of cadmium adsorption on complexes was lower than that on goethite at pH 6. 5. The cadmium adsorption and its maximum theoretical adsorption on both goethite and complexes were increased at the presence of phosphate. The coexistence of phosphate improved the adsorption affinity,the average adsorption rate constant(k)and the initial adsorption rate(h)at pH 6. 5. The inhibitive effects of increase of ionic strength on cadmium adsorption on goethite and humic acid-coated goethite complexes were also weakened by the presence of phosphate.
The aim of this study is to investigate the adsorption characteristics of cadmium on goethite(G)and humic acid-coated goethite complexes(GH)under the application of phosphate by the isotherm and kinetic adsorption experiments. The effects of pH and ionic strength on cadmium adsorption were also determined. The results show that both the specific surface area and the isoelectric point of humic acid-coated goethite complexes were lower than those of goethite.However,the surface sites density of the complexes coated by humic acid was higher than that of goethite. The Langmuir equation and pseudo-second-order model were applied to describe the isotherm and kinetic adsorption of cadmium on goethite and humic acid-coated goethite complexes,respectively,and the better fitting effects were achieved. The presence of humic acid coated on goethite enhanced the maximum adsorption(X_m,q_e) and the adsorption affinity(K_L) of cadmium.With the increase of ionic strength,the reduction rate of cadmium adsorption on goethite was lower than that on complexes at pH 4. 5,while the reduction rate of cadmium adsorption on complexes was lower than that on goethite at pH 6. 5. The cadmium adsorption and its maximum theoretical adsorption on both goethite and complexes were increased at the presence of phosphate. The coexistence of phosphate improved the adsorption affinity,the average adsorption rate constant(k)and the initial adsorption rate(h)at pH 6. 5. The inhibitive effects of increase of ionic strength on cadmium adsorption on goethite and humic acid-coated goethite complexes were also weakened by the presence of phosphate.
引文
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[13]KAISER K,GUGGENBERGER G.Mineral Surfaces and Soil Organic Matter[J].European Journal of Soil Science,2003,54(2):219-236.
[14]TOMBáCZ E,LIBOR Z,ILLéS E,et al.The Role of Reactive Surface Sites and Complexation by Humic Acids in the Interaction of Clay Mineral and Iron Oxide Particles[J].Organic Geochemistry,2004,35(3):257-267.
[15]ALCACIO T,HESTERBERG D,CHOU J W,et al.Molecular Scale Characteristics of Cu(Ⅱ)Bonding in Goethite-Humate Complexes[J].Geochimica et Cosmochimica Acta,2001,65(9):1355-1366.
[16]COVELO E F,VEGA F A,ANDRADE M L.Sorption and Desorption of Cd,Cr,Cu,Ni,Pb and Zn by a Fibric Histosol and Its Organo-Mineral Fraction[J].Journal of Hazardous Materials,2008,159(2/3):342-347.
[17]罗文倩,魏世强.镉在针铁矿、针铁矿-腐殖酸复合胶体中吸附解吸行为比较研究[J].农业环境科学学报,2009,28(5):897-902.[LUO Wen-qian,WEI Shi-qiang.Adsorption and Desorption Behaviors of Cadmium On/From Goethite and Its Compound Colloid With Humic Acids[J].Journal of Agro-Environment Science,2009,28(5):897-902.]
[18]王丹丽,王恩德.针铁矿及腐殖质对水体重金属离子的吸附作用[J].安全与环境学报,2001,1(4):1-4.[WANG Dan-li,WANG En-de.Adsorption of Heavy Metal Ions in Aqueous-Solution Onto Goethite and Humin[J].Journal of Safety and Environment,2001,1(4):1-4.]
[19]LI W,ZHANG S Z,SHAN X Q.Surface Modification of Goethite by Phosphate for Enhancement of Cu and Cd Adsorption[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2007,293(1/2/3):13-19.
[20]范玉超,夏睿智,刘薇,等.模拟酸雨对磷基材料稳定化土壤Cu、Cd、Pb和P活性的影响[J].生态与农村环境学报,2018,34(5):441-447.[FAN Yu-chao,XIA Rui-zhi,LIU Wei,et al.Effects of Simulated Acid Rain on the Availability of Cu,Cd,Pb and P in a Contaminated Soil Immobilized by Phosphorus-Based Materials[J].Journal of Ecology and Rural Environment,2018,34(5):441-447.]
[21]WANG H,ZHU J,FU Q L,et al.Phosphate Adsorption on Uncoated and Humic Acid-Coated Iron Oxides[J].Journal of Soils and Sediments,2016,16(7):1911-1920.
[22]XIONG J,KOOPAL L K,WENG L P,et al.Effect of Soil Fulvic and Humic acid on Binding of Pb to Goethite-Water Interface:Linear Additivity and Volume Fractions of HS in the Stern Layer[J].Journal of Colloid and Interface Science,2015,457:121-130.
[23]FEIN J B,BOILY J F,YEE N,et al.Potentiometric Titrations of Bacillus subtilis Cells to Low pH and a Comparison of Modeling Approaches[J].Geochimica et Cosmochimica Acta,2005,69(5):1123-1132.
[24]NIU Z W,FAN Q H,WANG W H,et al.Effect of pH,Ionic Strength and Humic Acid on the Sorption of Uranium(Ⅵ)to Attapulgite[J].Applied Radiation Isotopes,2009,67(9):1582-1590.
[25]LüTZENKIRCHEN J.Ionic Strength Effects on Cation Sorption to Oxides:Macroscopic Observations and Their Significance in Microscopic Interpretation[J].Journal of Colloid and Interface Science,1997,195(1):149-155.
[26]ELZINGA E J,KRETZSCHMAR R.In situ ATR-FTIR Spectroscopic Analysis of the Co-Adsorption of Orthophosphate and Cd(Ⅱ)Onto Hematite[J].Geochimica et Cosmochimica Acta,2012,117:53-64.
[27]刘凡,介晓磊,贺纪正,等.不同pH条件下针铁矿表面磷的配位形式及转化特点[J].土壤学报,1997,34(4):367-374.[LIU Fan,JIE Xiao-lei,HE Ji-zheng,et al.Coordination Forms and Transformations of Phosphate Adsorbed by Goethite Surface on Different pH[J].Acta Pedologica Sinica,1997,34(4):367-374.]
[28]WANG K J,XING B S.Adsorption and Desorption of Cadmium by Goethite Pretreated With Phosphate[J].Chemosphere,2002,48(7):665-670.
[29]李学垣.土壤化学[M].北京:高等教育出版社,2001:22-23.[LI Xue-yuan.Soil Chemistry[M].Beijing:Higher Education Press,2001:22-23.]
[2]左清青,王烁康,赵陈晨,等.纳米羟基磷灰石对镉的吸附解吸及对镉污染土壤修复研究[J].环境工程,2017,35(3):179-183,151.[ZUO Qing-qing,WANG Shuo-kang,ZHAOChen-chen,et al.Adsorption and Desorption of Cd on nHAP and Remediation Test on Cd Contamination Soil[J].Environmental Engineering,2017,35(3):179-183,151.]
[3]黄荣,徐应明,黄青青,等.不同氮磷钾肥对海泡石钝化修复镉污染土壤的稳定性研究[J].生态与农村环境学报,2018,34(6):547-553.[HUANG Rong,XU Ying-ming,HUANGQing-qing,et al.Effects of Nitrogen,Phosphate and Potassium Fertilizer on In-situ Remediation of Cd Polluted Paddy Soil With Sepiolete[J].Journal of Ecology and Rural Environment,2018,34(6):547-553.]
[4]MOHAPATRA M,MOHAPATRA L,SINGH P,et al.A Comparative Study on Pb(Ⅱ),Cd(Ⅱ),Cu(Ⅱ),Co(Ⅱ)Adsorption From Single and Binary Aqueous Solutions on Additive Assisted Nano-Structured Goethite[J].International Journal of Engineering,Science and Technology,2010,2(8):89-103.
[5]RANDALL S R,SHERMAN D M,RAGNARSDOTTIR K V,et al.The Mechanism of Cadmium Surface Complexation on Iron Oxyhydroxide Minerals[J].Geochimica et Cosmochimica Acta,1999,63(19/20):2971-2987.
[6]杨咏华.镉离子(Ⅱ)在针铁矿表面化学吸附的理论研究[D].青岛:中国海洋大学,2008.[YANG Yong-hua.Theoretical Research on Adsorption of Heavy Metal Cadmium Ion on Goethite[D].Qingdao:Ocean University of China,2008.]
[7]MUSTAFA G,SINGH B,KOOKANA R S.Cadmium Adsorption and Desorption Behaviour on Goethite at Low Equilibrium Concentrations:Effects of pH and Index Cations[J].Chemosphere,2004,57(10):1325-1333.
[8]GRANADOS-CORREA F,CORRAL-CAPULIN N G,OLGUíN MT,et al.Comparison of the Cd(Ⅱ)Adsorption Processes Between Boehmite(γ-AlOOH)and Goethite(α-FeOOH)[J].Chemical Engineering Journal,2011,171(3):1027-1034.
[9]管宇立,赵转军,赵立芳,等.碳铁共沉物对水中镉的吸附性能[J].工业水处理,2018,38(3):25-29.[GUAN Yu-li,ZHAO Zhuan-jun,ZHAO Li-fang,et al.Research on the Adsorption Capability of Iron-Carbon Co-Precipitant for Cadmium in Water[J].Industrial Water Treatment,2018,38(3):25-29.]
[10]张桂银,毕淑琴,董元彦,等.有机酸对针铁矿和三羟铝石吸附镉离子的影响[J].河北农业大学学报,2002,25(4):49-52.[ZHANG Gui-yin,BI Shu-qin,DONG Yuan-yan,et al.Effects of Organic Acids on Sorption of Cadmiumion on Goethite and Bayerite[J].Journal of Agricultural University of Hebei,2002,25(4):49-52.]
[11]魏世勇,谭文峰,刘凡.土壤腐殖质-矿物质交互作用的机制及研究进展[J].中国土壤与肥料,2009(1):1-6.[WEI Shi-yong,TAN Wen-feng,LIU Fan.Advances on the Study of Mineral-Humus Interactions in Soils[J].Soil and Fertilizers Sciences in China,2009(1):1-6.]
[12]李春玲,罗庆军,李春峰.Zn2+、Cd2+在腐殖酸上的吸附动力学与解吸作用研究[J].腐植酸,2017(5):20-25.[LI Chun-ling,LUO Qing-jun,LI Chun-feng.Study of Adsorptive Kinetics and Desorption of Zn2+,Cd2+ on Humic Acid[J].Humic Acid,2017(5):20-25.]
[13]KAISER K,GUGGENBERGER G.Mineral Surfaces and Soil Organic Matter[J].European Journal of Soil Science,2003,54(2):219-236.
[14]TOMBáCZ E,LIBOR Z,ILLéS E,et al.The Role of Reactive Surface Sites and Complexation by Humic Acids in the Interaction of Clay Mineral and Iron Oxide Particles[J].Organic Geochemistry,2004,35(3):257-267.
[15]ALCACIO T,HESTERBERG D,CHOU J W,et al.Molecular Scale Characteristics of Cu(Ⅱ)Bonding in Goethite-Humate Complexes[J].Geochimica et Cosmochimica Acta,2001,65(9):1355-1366.
[16]COVELO E F,VEGA F A,ANDRADE M L.Sorption and Desorption of Cd,Cr,Cu,Ni,Pb and Zn by a Fibric Histosol and Its Organo-Mineral Fraction[J].Journal of Hazardous Materials,2008,159(2/3):342-347.
[17]罗文倩,魏世强.镉在针铁矿、针铁矿-腐殖酸复合胶体中吸附解吸行为比较研究[J].农业环境科学学报,2009,28(5):897-902.[LUO Wen-qian,WEI Shi-qiang.Adsorption and Desorption Behaviors of Cadmium On/From Goethite and Its Compound Colloid With Humic Acids[J].Journal of Agro-Environment Science,2009,28(5):897-902.]
[18]王丹丽,王恩德.针铁矿及腐殖质对水体重金属离子的吸附作用[J].安全与环境学报,2001,1(4):1-4.[WANG Dan-li,WANG En-de.Adsorption of Heavy Metal Ions in Aqueous-Solution Onto Goethite and Humin[J].Journal of Safety and Environment,2001,1(4):1-4.]
[19]LI W,ZHANG S Z,SHAN X Q.Surface Modification of Goethite by Phosphate for Enhancement of Cu and Cd Adsorption[J].Colloids and Surfaces A:Physicochemical and Engineering Aspects,2007,293(1/2/3):13-19.
[20]范玉超,夏睿智,刘薇,等.模拟酸雨对磷基材料稳定化土壤Cu、Cd、Pb和P活性的影响[J].生态与农村环境学报,2018,34(5):441-447.[FAN Yu-chao,XIA Rui-zhi,LIU Wei,et al.Effects of Simulated Acid Rain on the Availability of Cu,Cd,Pb and P in a Contaminated Soil Immobilized by Phosphorus-Based Materials[J].Journal of Ecology and Rural Environment,2018,34(5):441-447.]
[21]WANG H,ZHU J,FU Q L,et al.Phosphate Adsorption on Uncoated and Humic Acid-Coated Iron Oxides[J].Journal of Soils and Sediments,2016,16(7):1911-1920.
[22]XIONG J,KOOPAL L K,WENG L P,et al.Effect of Soil Fulvic and Humic acid on Binding of Pb to Goethite-Water Interface:Linear Additivity and Volume Fractions of HS in the Stern Layer[J].Journal of Colloid and Interface Science,2015,457:121-130.
[23]FEIN J B,BOILY J F,YEE N,et al.Potentiometric Titrations of Bacillus subtilis Cells to Low pH and a Comparison of Modeling Approaches[J].Geochimica et Cosmochimica Acta,2005,69(5):1123-1132.
[24]NIU Z W,FAN Q H,WANG W H,et al.Effect of pH,Ionic Strength and Humic Acid on the Sorption of Uranium(Ⅵ)to Attapulgite[J].Applied Radiation Isotopes,2009,67(9):1582-1590.
[25]LüTZENKIRCHEN J.Ionic Strength Effects on Cation Sorption to Oxides:Macroscopic Observations and Their Significance in Microscopic Interpretation[J].Journal of Colloid and Interface Science,1997,195(1):149-155.
[26]ELZINGA E J,KRETZSCHMAR R.In situ ATR-FTIR Spectroscopic Analysis of the Co-Adsorption of Orthophosphate and Cd(Ⅱ)Onto Hematite[J].Geochimica et Cosmochimica Acta,2012,117:53-64.
[27]刘凡,介晓磊,贺纪正,等.不同pH条件下针铁矿表面磷的配位形式及转化特点[J].土壤学报,1997,34(4):367-374.[LIU Fan,JIE Xiao-lei,HE Ji-zheng,et al.Coordination Forms and Transformations of Phosphate Adsorbed by Goethite Surface on Different pH[J].Acta Pedologica Sinica,1997,34(4):367-374.]
[28]WANG K J,XING B S.Adsorption and Desorption of Cadmium by Goethite Pretreated With Phosphate[J].Chemosphere,2002,48(7):665-670.
[29]李学垣.土壤化学[M].北京:高等教育出版社,2001:22-23.[LI Xue-yuan.Soil Chemistry[M].Beijing:Higher Education Press,2001:22-23.]