改性方法对ATP孔道结构及Cr^(6+)吸附性能研究

Influence of different modification methods on pore structure and Cr^(6+) adsorption of ATP

凹凸棒石(ATP)作为天然二维纳米材料,因具有丰富孔道和较大比表面积被广泛用于水处理吸附剂,但其中含有大量杂质需提纯改性以期提高其吸附效率。文中研究焙烧、酸碱、水热、微波等一系列手段改性的凹凸棒石孔道结构变化及对水体中重金属离子Cr^(6+)的去除效果。研究结果证明:不同提纯改性方法对ATP的官能团、价键及孔道结构均产生影响。ATP-0(天然矿物)、ATP-1(碱焙烧)产物的吸附脱附曲线符合Ⅰ型等温线,说明以微孔为主;ATP-2(酸水热活化)、ATP-3(酸水热+碱改活化)及ATP-4(酸微波+碱改活化)的吸附曲线逐渐向Ⅳ型等温线转化,存在滞后环,孔道大小顺序为ATP-4>APT-3>ATP-2。吸附过程一般24—48 h达到平衡,对Cr^(6+)吸附效率强弱顺序为:ATP-4>ATP-3>ATP-2>ATP-0>ATP-1,ATP-4吸附效率达89.62%,吸附容量为18.32 mg/g。

Attapulgite （ATP） as natural two-dimensional nanomaterials, is widely used in water treatment adsorbents for abundant pore and large specific surface area, however, the plenty impurities are essential to remove from ATP by purifying and modifying to improve the adsorption efficiency. In this paper, the structure of modified ATP by calcination, acid-base, hydrothermal, microwave and other methods , and the removal effect of heavy metal ions Cr^6＋ in polluted water were studied. The research results show that the effects of different modification methods on the functional groups, valence bond and pore structure of ATP are investigated. The nitrogen adsorption- desorption isotherms of products between ATP-O（naturalmineral） and ATP-1 （alkaline calcinations）belonged to the I isotherm according to IUPAC. Micropores were the major pores of them. The isotherms of ATP-2 （acid hydrothermal activation）, ATP-3 （acid hydrothermal ＋ alkali activation） and ATP-4 （acid microwave ＋ alkali activation） were gradually transformed into the 1V isotherm, and desorption hysteresis is significant. The order of pore size is ATP-4 〉 APT-3 〉 ATP-2. The equilibrium period of the adsorption is 24-48 h, the order of Cr^6＋ adsorption efficiency is ：ATP-4 〉 ATP-3 〉 ATP-2 〉 ATP-O 〉 ATP-1, the removal efficiency of ATP-4 is 89.62%, and the adsorption capacity is 18.32 mg/g.