Liu Minmin, Hou Li-An, Yu Shuili, Xi Beidou, Zhao Ying, Xia Xunfeng
State Key Laboratory of Pollution Control and Resource Reuse,, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, PR China.
State Key Laboratory of Environmental Criteria and Risk Assessment, China Research Academy of Environmental Science, Beijing 200012, PR China.
Chem Eng J. 2013 May 1;223(100):678-687. doi: 10.1016/j.cej.2013.02.088.
In this paper, the MCM-41 has been modified by impregnation with zeolite A to prepare a kind of new adsorbent. The adsorption of TC from aqueous solutions onto modified MCM-41 has been studied. It was discovered that the adsorption capability of zeolite A modified MCM-41 (A-MCM-41) increased dramatically after modification. The modified MCM-41 was characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, Fourier Transform Infrared (FTIR) analysis, Transmission electron microscopy (TEM) images, and Si and Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectra. The modified MCM-41 structure was still retained after impregnated with zeolite A but the surface area and pore diameter decreased due to pore blockage. The adsorption of TC on modified MCM-41 was discussed regarding various parameters such as pH, initial TC concentration, and the reaction time. The pH effects on TC adsorption indicated that the adsorbents had better adsorption performances in acidic and neutral conditions. The adsorption isotherms were fitted well by the Langmuir model. The adsorption kinetics was well described by both pseudo-second order equation and the intra-particle diffusion model. The adsorption behavior in a fixed-bed column system followed Thomas model. The adsorption behavior of TC was the chemical adsorption with an ion exchange process and electrostatic adsorption.
本文通过用A型沸石浸渍对MCM-41进行改性,制备了一种新型吸附剂。研究了改性MCM-41对水溶液中四环素(TC)的吸附性能。发现经A型沸石改性后的MCM-41(A-MCM-41)吸附能力显著提高。采用X射线衍射(XRD)、氮气吸附-脱附、傅里叶变换红外(FTIR)分析、透射电子显微镜(TEM)图像以及硅和铝魔角旋转核磁共振(MAS NMR)光谱对改性MCM-41进行了表征。用A型沸石浸渍后,改性MCM-41的结构仍然保留,但由于孔堵塞,比表面积和孔径减小。讨论了pH值、初始TC浓度和反应时间等各种参数对改性MCM-41吸附TC的影响。pH值对TC吸附的影响表明,吸附剂在酸性和中性条件下具有较好的吸附性能。吸附等温线符合Langmuir模型。吸附动力学能用准二级方程和颗粒内扩散模型很好地描述。固定床柱系统中的吸附行为符合Thomas模型。TC的吸附行为是一种伴有离子交换过程和静电吸附的化学吸附。