改性蜂窝煤渣吸附Cr(Ⅵ)的动力学和热力学性能

Adsorption kinetics and thermodynamics of Cr(Ⅵ) on modified honeycomb-cinder

利用碳酸钡对蜂窝煤渣进行改性,通过粉末X射线衍射光谱(XRD)和扫描电镜(SEM)对改性前后蜂窝煤渣的物质组成和形貌进行表征,研究了改性蜂窝煤渣吸附Cr(Ⅵ)的动力学和热力学性能。实验结果表明,改性蜂窝煤渣对Cr(Ⅵ)具有良好的吸附能力,吸附过程符合准二级吸附动力学模型。分别用Langmuir、Freundlich、D-R和Tempkin等4种吸附等温线模型对实验数据进行拟合,Langmuir方程拟合效果最好,25、35和45℃下的饱和吸附量分别为2.985、2.562和2.630 mg/g。D-R和Tempkin模型研究表明,吸附过程属于物理吸附。热力学研究表明,改性蜂窝煤渣对Cr(Ⅵ)的吸附是一个自发的、放热过程。

Honeycomb-cinder was modified by barium carbonate to adsorbe Cr（VI） from simulated chromium-containing wastewater. The powder X-ray diffraction spectrum （XRD）and scanning electron microscope （SEM） were applied to analyze the compositions and morphology of the cinder before and after modification. The adsorption thermodynamics and kinetics of Cr（VI） on modified honeycomb-cinder were investigated completely and systematically,which show that modified cinder has a good adsorption capacity for Cr（VI）. The adsorption process can be described well by pseudo-second-order kinetic equation. The adsorption isothermal data were fitted with the Langmuir, Freundlich, D-R and Tempkin equations, the results show that the adsorption process agrees well with the Langmuir model. The equilibrium adsorption capacities of Cr （VI） are 2. 985,2. 562 and 2. 630 mg/g at 25,35 and 45℃ , respectively. The study of D-R and Tempkin isotherm indicates the adsorption process is mediated by physical adsorption mechanism. The thermodynamics analysis shows that the adsorption processes are spontaneous and exothermic