有机蒙脱土的制备表征及其对4-氯酚的吸附性能研究

以十六烷基三甲基溴化铵(CTAB)为有机化试剂,利用溶液插层法,通过控制CTAB的投加量成功制备了不同有机化程度的蒙脱土,使用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、扫描电镜(SEM)与透射电镜(TEM)对其结构进行了表征.以去除率(R)和吸附量(q)为评价指标,探讨了田口-灰色关联分析方法多目标优化有机蒙脱土对水中4-氯酚的吸附反应条件的可行性.考察了吸附动力学和吸附热力学行为.结果表明,CTAB成功插入到蒙脱土的片层间,有机蒙脱土的层间距随着CTAB投加量的增加而增大,CTAB在蒙脱土片层间的排列方式也由平卧单层和倾斜单层转为倾斜双层.田口-灰色关联分析可知,在以2倍蒙脱土离子交换容量制备的有机蒙脱土为吸附剂(CTM4)、4-氯酚溶液pH值为6、浓度为150 mg·L-1、固液比为0.6 g·L-1和反应时间90 min的条件下,可实现4-氯酚的去除率和吸附容量的同时优化,此时去除率和吸附容量分别为36.85%和91.07 mg·g-1.CTM4对4-氯酚的吸附更符合拟二级动力学方程,整个吸附过程可能是由膜扩散和颗粒内扩散共同作用的结果.Langmuir和Freundlich吸附等温方程均能较好地描述CTM4对4-氯酚的吸附行为.吸附过程的热力学参数表明,CMT4对4-氯酚的吸附是一个自发的放热反应.

Preparation,Characterization of Organic Montmorillonite and Its Adsorption Properties of 4-chlorophenol

The cetyltrimethylammonium bromide (CTAB) modified montmorillonite (MMT) composites were prepared by polymer solution intercalation and characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM).The Taguchi design and grey relational analysis were applied to explore effective parameters for simultaneously achieving a higher removal percentage (R) and adsorption capacity (q) of 4-chlorophenol (4-CP) using organic montmorillonite as adsorbent.The adsorption kinetics and thermodynamics behavior were investigated in detail.The results indicate that CTAB has been successfully insert into the montmorillonite layers and the interlayer spacing of organic montmorillonite increase with the increasing of CTAB dosage, and the arrangement of CTAB in montmorillonite layer is changed from lateral monolayer and paraffin-type monolayer to paraffin-type bilayer.The multi-objectives adsorption conditions are determined as pH=6, initial concentration of 150 mg·L-1, solid/liquid ratio of 0.6 g·L-1, reaction time 90 min, organic montmorillonite prepared by 2 times the cation exchange capacity (CEC) as adsorbent.Under the condition, the R and q are 36.85% and 91.07 mg·g-1, respectively.The adsorption of 4-CP is best fitted by the pseudo-second-order kinetics equation, and the adsorption process is probably due to the interaction of film diffusion and intraparticle diffusion.In addition, both Langmuir and Freundlich isotherms can apply to 4-CP adsorption by CMT4.The thermodynamic parameters indicated that the adsorption process of 4-CP is a spontaneous and exothermic reaction.