富里酸-膨润土复合体对氟的吸附特性  

Adsorption Properties of Fluorine onto Fulvic Acid-Bentonite Complex

作　　者：方敦[1] 田华婧 叶欣[2] 何次利 但悠梦[2] 魏世勇[2] 

机构地区：[1]湖北民族学院科技学院,恩施445000 [2]湖北民族学院化学与环境工程学院,恩施445000

出　　处：《环境科学》2016年第3期1023-1031,共9页Environmental Science

基　　金：国家自然科学基金项目(41261060);湖北民族学院科技学院校级项目(KY201414);湖北民族学院大学生创新创业训练计划项目(2014Z005)

摘　　要：采用共沉淀法制备了富里酸-膨润土复合体(FA-BENT),研究了FA-BENT的基本性质及其在不同环境条件下对氟的吸附特性.XRD分析显示,FA-BENT中蒙脱石的(001)面衍射峰强度有所减弱,但其层间距没有明显变化,表明FA-BENT中富里酸主要包被在膨润土外表面.FTIR结果表明,FA-BENT膨润土的矿物组分主要与富里酸表面C=O、—OH等官能团结合,配位体交换、表面络合作用是其主要作用机制.低p H范围内,升高反应体系的初始p H有利于FA-BENT对氟的吸附;当初始p H上升至4.50以后,吸附量随p H升高而降低;FA-BENT对氟的吸附也受离子强度的影响,其主要原因可能是"极性"效应;FA-BENT对氟的动力学吸附过程遵循拟二级动力学机制,受化学过程控制(R^2=0.999 2);与Freundlich模型相比,Langmuir模型对氟在FA-BENT上的吸附数据具有较高的拟合优度(R^2>0.994 9).热力学参数表明,FA-BENT对氟的吸附属于熵驱动的自发吸热反应过程[ΔH为32.57 k J·mol^(-1),ΔS为112.31 J·(mol·K)^(-1),ΔG为-0.65^-1.76 k J·mol^(-1)].Fulvic Acid-Bentonite（ FA-BENT） complex was prepared using coprecipitation method,and basic properties of the complex and sorption properties of fluorine at different environmental conditions were studied. XRD results showed that the d001 spacing of FABENT complex had no obvious change compared with the raw bentonite,although the diffraction peak intensity of smectite in FA-BENT complex reduced,and indicated that FA mainly existed as a coating on the external surface of bentonite. Some functional groups（ such as C=O,—OH,etc.） of FA were observed in FA-BENT FTIR spectra,thus suggesting ligand exchange-surface complexation between FA and bentonite. Higher initial p H values of the reaction system were in favor of the adsorption of fluorine onto FA-BENT,while the equilibrium capacity decreased with the increase of p H at initial p H≥4. 50. The adsorption of fluorine onto FA-BENT was also affected by ionic strength,and the main reason might be the＂polarity＂effect. The adsorption of fluorine onto FA-BENT followed pseudo-second-order kinetic model and was controlled by chemical process（ R^2= 0. 999 2）. Compared with the Freundlich model,Langmuir model was apparently of a higher goodness of fit（ R^2 0. 994 9） for absorption of fluorine onto FA-BENT. Thermodynamic parameters indicated that the adsorption process of fluorine was an spontaneously endothermic reaction,and was an entropy-driven process（ ΔH 32. 57 k J·mol^（-1）,ΔS 112. 31 J·（ mol·K）^（-1）,ΔG- 0. 65-- 1. 76 k J·mol^（-1））.

关 键 词：富里酸 膨润土 复合体 氟 吸附 

分 类 号：X131.3[环境科学与工程—环境科学] X53