有机蛭石的制备及其对2,4-二氯酚的吸附性能研究

Preparation of organic vermiculite and application for adsorption of 2,4-dichlorophenol from aqueous solutions

用十六烷基三甲基溴化铵(HDTMA)以不同倍数阳离子交换容量对蛭石进行有机改性,制得有机蛭石,用XRD和FT-IR手段对有机蛭石进行表征,考察了吸附时间、pH值和温度等对有机蛭石吸附有机污染物2,4-二氯酚(2,4-DCP)的吸附效果的影响,并采用Langmuir和Freundlich方程进行拟合,研究其吸附机理。实验结果表明,HDTMA成功进入蛭石层间。相对于蛭石原土吸附量12.72mg/g,改性后的有机蛭石对2,4-DCP的吸附能力均得到显著提高,1.0倍CEC有机蛭石吸附量为90.12mg/g。在酸性条件下,吸附效果更好。Langmuir和Freundlich吸附等温模型均可较好地用来描述1.0倍CEC改性的有机蛭石对2,4-DCP的吸附等温线。有机蛭石对2,4-DCP的吸附量随温度的升高而下降。通过热力学分析发现有机蛭石吸附2,4-DCP是一个自发的吸附过程,低温有利于吸附,材料解吸率不大。

Organic vermiculites were obtained by modifying raw vermiculite with hexadecyltrimethylammonium bromide （HDTMA） at different concentrations, and characterized by X-ray diffraction （XRD） spectra and Fou- rier transform infrared （FT-IR） spectra. Then these organic vermiculites were assessed for adsorption of 2,4- dichlorophenol （2,4-DCP） and the effects of adsorption, pH and temperature on adsorption were all discussed. Experimental results were fit with Langmuir and Freundlich equations and mechanism of adsorption was dis- cussed. The experiment results showed that alkylammonium cations can enter into the interlayer of vermiculite successfully. Compared to raw vermiculite of 12.72mg/g, the adsorption capacity of organic vermiculites were increased significantly and equilibrium adsorption quality of OVMT-1.0 reached 90.12mg/g. There was a better adsorption effect under acidic conditions. The results showed that the isothermal data of 2,4-DCP adsorption on OVMT-1.0 fit well to Langmuir and Freundlich equations. The adsorption capacity of 2,4-DCP on organic ver- miculite decreased with the increase in temperature. Thermodynamic analysis suggested that the adsorption be- havior was a spontaneous physical adsorption process and low temperature was of benefit to adsorption. The de- sorption rates of materials were low.