改性甘蔗渣吸附废水中低浓度Cd^(2+)和Cr^(3+)的研究  

Investigation of the Characteristics of Adsorption of Low-Concentration Cd^(2+) and Cr^(3+) by Modified Sugarcane Bagasse

作　　者：熊佰炼[1] 崔译霖[2] 张进忠[1,3] 张明晓[4] 邢赜[1] 

机构地区：[1]西南大学资源环境学院,重庆400716 [2]贵州师范大学化学材料学院,贵阳550001 [3]重庆市农业资源与环境重点实验室,重庆400716 [4]西南大学化学化工学院,重庆400716

出　　处：《西南大学学报（自然科学版）》2010年第1期118-123,共6页Journal of Southwest University(Natural Science Edition)

摘　　要：在微波作用下,用尿素改性甘蔗渣制备螯合型吸附剂.采用静态摇瓶实验,研究了改性甘蔗渣吸附低浓度Cd2+和Cr3+的影响因素、动力学和热力学特性.结果表明,吸附Cd2+和Cr3+的最佳pH分别为6和4;吸附平衡时间分别为2 h和12 h;温度对吸附的影响不显著.改性甘蔗渣吸附Cd2+和Cr3+的动力学过程可以用二级动力学模型描述;Cd2+的等温吸附行为可以用Langmuir和Freundlich方程描述,Cr3+的吸附行为可以用Langmuir方程描述,它们的饱和吸附量分别为12.38 mg/g,23.92 mg/g;吸附Cd2+和Cr3+的ΔH分别为-5.70 kJ/mol和33.36 kJ/mol,ΔS分别为-25.28 J/(mol.K)和165.47 J/(mol.K);在290-320 K时,吸附Cd2+和Cr3+的ΔG分别为-13.09～-13.77 kJ/mol和-15.05～-19.91 kJ/mol;改性甘蔗渣吸附Cd2+和Cr3+分别为自发进行的放热和吸热过程.通过对甘蔗渣改性前后、吸附重金属离子前后的红外光谱分析,改性渣吸附Cd2+和Cr3+起重要作用的基团是为酰胺官能团.Under the irradiation of microwave,sugarcane bagasse was modified by urea to prepare a chelating adsorbent.The influencing factors of the adsorption of low-concentration Cd^2＋ and Cr^3＋ by modified sugarcane bagasse and its kinetic and thermodynamic characteristics were studied using static-state shaking experiment.The optimal pH values of the adsorption solutions for Cd^2＋ and Cr^3＋ were 6.0 and 4.0 and the equilibrium time for the adsorption of Cd^2＋ and Cr^3＋ were 2 h and 12 h,respectively,while temperature had no significant effect on adsorption.The adsorption processes for Cd^2＋ and Cr^3＋ by sugarcane bagasse can be described by the second kinetic equation,and the isothermal adsorption behavior for Cd2＋ by Langmuir and Freundlich equations,while Langmuir equation can be used to describe the adsorption of Cr3＋.The saturated adsorption quantities of Cd^2＋ and Cr^3＋ were 12.38 mg/g and 23.92 mg/g,the changes in enthalpy（ΔH） were-5.70 kJ/mol and 33.36 kJ/mol,and the changes in entropy（ΔS） were-25.28 J/（mol·K） and 165.47 J/（mol·K）,respectively.When the temperature was in the range of 290 K to 320 K,the Gibbs free energies（G） of Cd^2＋ and Cr^3＋ were from-13.09 to-13.77 kJ/mol and from-15.05 to 19.91 kJ/mol,respectively,indicating that the adsorption is a spontaneous exothermic process for Cd2＋ and a spontaneous endothermic process for Cr3＋.Infrared spectroscopy showed that acylamide functional group plays an important role in the adsorption of the modified bagasse to Cd^2＋ and Cr^3＋.

关 键 词：改性甘蔗渣 重金属 吸附 动力学 热力学 

分 类 号：X703[环境科学与工程—环境工程]