多孔性Mn_3O_4的制备及其对水中镉的吸附  

Preparation of porous Mn_3O_4 and its adsorption for cadmium in water

作　　者：李长安[1] 刘伟[1] 陈上[1] 

机构地区：[1]吉首大学化学化工学院,吉首416000

出　　处：《环境工程学报》2013年第2期535-540,共6页Chinese Journal of Environmental Engineering

基　　金：湖南省教育厅自然科学基金资助项目(07B060)

摘　　要：采用硫酸锰水解-氧化两步法制备了多孔性四氧化三锰,以X射线衍射、扫描电镜和氮吸附比表面仪对其进行了表征,研究了该多孔性Mn3O4在不同的溶液pH值、吸附时间、投加量和温度下对水中Cd(Ⅱ)的吸附行为,并测定了吸附过程的动力学和热力学参数。实验结果表明,该法合成的四氧化三锰属四方体心结构,一次晶粒尺寸为45.8 nm,颗粒间存在大量的孔洞,BET法比表面积为40.27 m2/g。在293 K,pH 5.5,吸附12 h时达到平衡,饱和吸附量为12.8 mg/g。该吸附过程符合准二级反应动力学模型,其反应的吸附活化能为2.743 kJ/mol,吸附等温线较好地符合Langmuir等温方程,吸附焓变和熵变均为正值,自由能变为负值,说明该吸附过程为自发的吸热过程。porous Mn3O4 was prepared by hydrolysis-oxidation method using manganese sulfate as raw material, the product was characterized by XRD,SEM and specific surface area analysis. Its adsorptive manners for Cd（ Ⅱ ） in water under different pH, times, dosages and temperatures were investigated, as well as kinetic and thermodynamic parameters of adsorption process. The results indicate that the prepared Mn3O4 is of body-centred tetragona], its primary size of crystallite is 45.8 nm, and exhibits porous structure with specific surface area of 40.27 m^2/g. The experiments show that adsorptions attain equilibrium after 12 h with saturated adsorptive capacity of 12.8 mg/g at 293 K and pH 5.5. The adsorption manner coincides with quasi-secondary order pattern, and its activation energy of adsorption is 2. 743 k J/tool. The adsorption isotherms fit fairly with Langmuir equation, the enthalpy and entropy change are of positive, whereas Gibbs free energy change is of negative, which indicate a endothermic and spontaneous process.

关 键 词：四氧化三锰 镉 吸附 动力学 热力学 

分 类 号：X703[环境科学与工程—环境工程]