改性兰炭末对对硝基苯酚的吸附平衡和动力学

Adsorption equilibrium and kinetics of p-nitrophenol on modified fine blue-coke

采用硝酸改性-高温活化法对废弃的兰炭末进行处理,对改性前后的兰炭末进行了SEM和BET表征,测定了改性后的兰炭末对对硝基苯酚的吸附性能,通过静态吸附实验研究了改性兰炭末对对硝基苯酚的吸附平衡和动力学特征。结果表明,兰炭末经改性后表面粗糙度明显增加,孔道明显增多,总孔容和比表面积分别增加了7.1倍和4.3倍;Langmuir方程可较好地描述对硝基苯酚在改性兰炭末上的吸附平衡,特征分离系数RL为0~1,为优惠吸附,温度升高有利于吸附的进行;动力学研究表明,对硝基苯酚在改性兰炭末上的吸附过程符合HO准二级动力学模型,颗粒外的液膜扩散是决定吸附速率的控制步骤,吸附过程的表观活化能Ea为9.825kJ/mol。改性兰炭末对对硝基苯酚有较好的吸附能力,328K下平衡吸附量达158.5mg/g,可作为一种廉价、高效的酚类废水处理用吸附剂,有很好的工业化应用前景。

The abandoned fine blue-coke was modified by the nitrate treatment-high temperature activation process.The raw materials and modified fine blue-coke(MFBC)were characterized by SEM and BET.The adsorption capacity of MFBC toward p-nitrophenol was measured.The adsorption equilibrium isotherms and kinetic curves of p-nitrophenol onto MFBC were investigated by the batch sorption experiments.The results show that the surface roughness of MFBC increases obviously.The total pore volume and specific surface area increase by 7.1and 4.3times,respectively.The equilibrium data are found to follow closely the Langmuir adsorption isotherm.The adsorption process is favorable adsorption as the feature separation factor RLis between 0and 1.In addition,the increment in temperature is beneficial for the adsorption process.The kinetic analysis demonstrates that the adsorption of p-nitrophenol onto MFBC can be best described by the HO pseudo-second-order equation.The liquid-film diffusion outside of particles is the main control step.The apparent active energy of the adsorption process(Ea)is 9.825kJ/mol.The MFBC exhibited good adsorption performance toward p-nitrophenol.The maximum sorption capacity of MFBC onto pnitrophenol is 158.5mg/g at 328 K.These results clearly indicate that the modified fine blue-coke(MFBC)has a potential industrial application as a low-cost adsorbent for treatment of wastewater containing p-nitrophenol.