水合二氧化锰对Co~(2+)的吸附行为研究
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摘要
以KMnO_4为原料合成了水合二氧化锰(HMO),采用XRD、BET、TG-DTA和FT-IR对HMO进行了表征。在此基础上,研究了各实验条件对HMO吸附Co~(2+)的影响,并将其用于含60 Co废水的实际处理研究。结果表明:HMO对溶液中的Co~(2+)具有良好吸附能力,在pH=7、T=298K条件下,其最大吸附量达132.98mg/g;溶液pH值能显著影响Co~(2+)在HMO上的吸附,在实验pH值范围内,吸附量随pH值增大而增加;在钴初始浓度相同的条件下,吸附量随温度升高而增加;Na~+、K~+、Mg~(2+)、Ca~(2+)、Zn~(2+)、Fe~(3+)等离子的存在对HMO吸附Co~(2+)具有一定影响。HMO对Co2+的吸附过程符合准二级动力学模型(R2>0.99),推测吸附过程中可能存在一定的化学吸附;吸附热力学行为可用Langmuir等温吸附方程进行描述(R2>0.99),表明Co~(2+)在HMO上为单分子层吸附;由吸附热力学数据ΔH=46.96kJ/mol、ΔG=-26.09kJ/mol可知,此吸附行为是自发进行的吸热反应。另外,在实际处理含60 Co废水的动态柱实验中,HMO对初始放射性浓度为2.78×105 Bq/L的60Co废液的去除率可达56.90%。
The hydrated manganese dioxide(HMO)was prepared by the oxidationreduction method with potassium permanganate as starting materials,while the resulted HMO was characterized by XRD,BET,TG-DTA and FT-IR.In the adsorption experiment,the influences of various experimental conditions were investigated,and HMO was also applied for the actual treatment of 60 Co wastewater.Experimental results showagood adsorption property of Co2+on HMO,in the condition of pH=7and T=298K,with a maximum adsorption capacity of 132.98mg/g.The pH of the solution can significantly affect Co2+adsorbed on HMO,and in the experimental pH range,the adsorption capacity increases with pH.Under the same Co2+initial concentration,the adsorption capacity increases with temperature.Co2+adsorption on HMO is influenced while Na+,K+,Mg2+,Ca2+,Zn2+and Fe3+coexisted in the solution.The adsorption behavior of Co2+on HMO is well described by pseudo-second-order kinetic model and Langmuir isotherm model(R2>0.99),and it is indicated that the adsorption process maybe a chemical and monolayer adsorption.The adsorption thermodynamics data ofΔH=46.96kJ/mol andΔG=-26.09kJ/mol show that the adsorption process is endothermic and spontaneous.In addition,when treating wastewater containing 60 Co whose initial radioactivity concentration is 2.78×105 Bq/L in the dynamic column experiment,the removal rate is 56.90%.
The hydrated manganese dioxide(HMO)was prepared by the oxidationreduction method with potassium permanganate as starting materials,while the resulted HMO was characterized by XRD,BET,TG-DTA and FT-IR.In the adsorption experiment,the influences of various experimental conditions were investigated,and HMO was also applied for the actual treatment of 60 Co wastewater.Experimental results showagood adsorption property of Co2+on HMO,in the condition of pH=7and T=298K,with a maximum adsorption capacity of 132.98mg/g.The pH of the solution can significantly affect Co2+adsorbed on HMO,and in the experimental pH range,the adsorption capacity increases with pH.Under the same Co2+initial concentration,the adsorption capacity increases with temperature.Co2+adsorption on HMO is influenced while Na+,K+,Mg2+,Ca2+,Zn2+and Fe3+coexisted in the solution.The adsorption behavior of Co2+on HMO is well described by pseudo-second-order kinetic model and Langmuir isotherm model(R2>0.99),and it is indicated that the adsorption process maybe a chemical and monolayer adsorption.The adsorption thermodynamics data ofΔH=46.96kJ/mol andΔG=-26.09kJ/mol show that the adsorption process is endothermic and spontaneous.In addition,when treating wastewater containing 60 Co whose initial radioactivity concentration is 2.78×105 Bq/L in the dynamic column experiment,the removal rate is 56.90%.
引文
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[2]RENGARAJ S,MOON S H.Kinetics of adsorption of Co(Ⅱ)removal from water and wastewater by ion exchange resins[J].Water Research,2002,36(7):1 783-1 793.
[3]MA B,OH S,SHIN W S,et al.Removal of Co2+,Sr2+and Cs+from aqueous solution by phosphate-modified montmorillonite(PMM)[J].Desalination,2011,276(1):336-346.
[4]YU B,CHEN J.Structure and cesium removal properties of a novel open-framework ecomaterial silicotitanate(Na4Ti4Si3O4)[J].Rare Metal Materials and Engineering,2002,31(1):539-542.
[5]GRANADOS-CORREA F,BULBULIAN S.Co(Ⅱ)adsorption in aqueous media by a synthetic Fe-Mn binary oxide adsorbent[J].Water,Air,&Soil Pollution,2012,223(7):4 089-4 100.
[6]GOGOI D,SHANMUGAMANI A G,RAO S V S,et al.Studies on adsorptive removal of radioactive cobalt from alkaline waste generated in sodium cooled fast breeder reactors[J].Journal of Radioanalytical and Nuclear Chemistry,2013,295(2):1 531-1 535.
[7]杨威,杨艳玲,李星,等.胶态水合二氧化锰絮凝粒子的结构形貌及其混凝机理[J].环境科学,2007,28(5):1 050-1 055.YANG Wei,YANG Yanling,LI Xing,et al.Morphology structure and the coagulation mechanism of the flocculation hydrated manganese dioxide colloidal particles[J].Environmental Science,2007,28(5):1 050-1 055(in Chinese).
[8]樊耀亭,吕秉玲,徐杰,等.水溶液中二氧化锰对铀的吸附[J].环境科学学报,1999,19(1):42-46.FAN Yaoting,LV Bingling,XU Jie,et al.Adsorption of uranium on manganese dioxide in the aqueous solution[J].Environmental Science,1999,19(1):42-46(in Chinese).
[9]陈国珍,黄贤智.紫外-可见分光光度法[M].北京:原子能出版社,1987.
[10]QIN Q,WANG Q,FU D,et al.An efficient approach for Pb(Ⅱ)and Cd(Ⅱ)removal using manganese dioxide formed in situ[J].Chemical Engineering Journal,2011,172(1):68-74.
[11]李余增.热分析[M].北京:清华大学出版社,1987.
[12]GRANADOS-CORREA F,JIMNEZ-BECERRIL J.Adsorption of 60 Co2+on hydrous manganese oxide powder from aqueous solution[J].Radiochimica Acta,2004,92(2):105-110.
[13]ZHU Z,ZHANG R,GE Y,et al.Removal of cadmium using MnO2 loaded D301 resin[J].Journal of Environmental Sciences,2007,19(6):652-656.
[14]SU Q,PAN B,PAN B,et al.Fabrication of polymer-supported nanosized hydrous manganese dioxide(HMO)for enhanced lead removal from waters[J].Science of the Total Environment,2009,407(21):5 471-5 477.
[15]杨威.水合氧化锰的净水机理与应用[M].北京:化学工业出版社,2008.