载铝改性沸石除氟的热力学和动力学机理研究

Study on the Thermodynamics and Kinetics of Removing Fluoride of Zeolite Modified by Al(Ⅲ)

本文依次采用1.0 mol/L的氢氧化钠和10%的硫酸铝改性天然沸石,然后经过焙烧得到载铝改性沸石样品。对天然沸石和改性沸石的吸附性能做了比较,考查了溶液p H值和温度对改性沸石吸附容量的影响,并对吸附过程进行了动力学和热力学研究。结果表明:改性沸石的吸附容量远远大于天然沸石,在溶液p H值为6,温度为室温时改性沸石的吸附容量达到最佳为1.44 mg/g;改性沸石对氟离子的吸附动力学符合准二级动力学方程,吸附热力学过程符合Freundlich模型,不同温度下的吸附热力学的吉布斯自由能以及焓变和熵变均为负值表明该吸附过程为自发放热反应;初步探讨了载铝改性沸石对氟离子吸附过程的反应机理。

In this paper,the natural zeolite was modified by using 1. 0 mol / L Na OH and 10 % Al2（ SO4）3,then was roasted in order to obtain Al（ Ⅲ）-zeolite samples. The adsorption performances were compared between natural zeolite and Al（ Ⅲ）-zeolite,the effects of p H and temperature on the adsorption capacity were also investigated as well as the kinetics and thermodynamics of removing fluoride process.The results show that the adsorption capacity of Al（ Ⅲ）-zeolite is much larger than that of natural zeolite,and the adsorption capacity can reach 1. 44 mg / g when the p H is 6 at room temperature; Pseudo second order equation best describe the adsorption process and the adsorption balance follows Freudlich isotherm model,the negative values of the gibbs free energy,the enthalpy and the entropy indicate the adsorption process is spontaneous and exothermic; A preliminary conclusion has been made to explain the adsorption mechanism of removing fluoride of Al（ Ⅲ）-zeolite.