Liang Dingcheng, Yu Fengqin, Xie Qiang, Chen Qingping, Liu Yuan, Zheng Yuhua, Zhu Keping, Zhang Zhijun, Liu Jun, Zhu Xiao, Liu Jinchang, Zhu Zihan
School of Chemical and Environmental Engineering, China University of Mining and Technology-Beijing, Beijing 100083, P. R. China.
State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, P. R. China.
ACS Appl Mater Interfaces. 2023 Aug 16;15(32):38781-38794. doi: 10.1021/acsami.3c06686. Epub 2023 Aug 4.
Activated carbon (AC) is a broad-spectrum adsorbent but is flammable and has low adsorption capacities for polar and/or high-boiling volatile organic compounds (VOCs), while zeolites exhibit high thermal stability but poor adsorption of macromolecular and nonpolar VOCs. In this study, zeolite/AC composites were synthesized with the aim of obtaining broad-spectrum, efficient, and safe adsorbents for VOCs. Dimethyldiallylammonium chloride (DDA)-modified AC was used as a carrier for an in situ hydrothermal reaction enabling assembly with zeolites due to electrostatic attraction. Interface models were constructed for their phases, which revealed the binding force and simulated the binding process. The adsorption and flame resistance of the composites were evaluated. The results showed that DDA effectively modified AC to give it a long-lasting positive charge in solutions. High-silicon and pure-silicon zeolites exhibited low negative charges or were even neutral; it was difficult to combine with the modified AC via electrostatic attractions. Instead, LTA zeolites with high aluminum contents and negative charges were used, and the seed-induction method was used. Ethanol and ultrasonic dispersion were used to prevent agglomeration of the seeds and modified AC powder, so they were self-assembled electrostatically. Moreover, the crystallization time was extended and composites with high zeolite loadings were successfully prepared. According to the model calculation, the binding energy between the zeolite and AC before and after the DDA modification were 324.97 and 1076.46 kcal mol, respectively, and the distance between them was shortened by 2.7 Å after DDA treatment. As a result, AC and zeolite combined more closely and exhibited a stronger binding energy. The adsorption capacity for highly polar dichloromethane was improved by zeolite loading on the AC, and the bed penetration time was doubled. However, impregnation with inorganic sodium enhanced the reactivities of the organic components in the composite, and the ignition point was slightly reduced. Furthermore, the electrostatic self-assembly method can expand to prepare the LTA zeolite/columnar AC composite from shaped AC, greatly improving its application prospects.
活性炭（AC）是一种广谱吸附剂，但易燃，对极性和/或高沸点挥发性有机化合物（VOCs）的吸附能力较低，而沸石具有较高的热稳定性，但对大分子和非极性VOCs的吸附性较差。在本研究中，合成了沸石/AC复合材料，旨在获得用于VOCs的广谱、高效和安全的吸附剂。用二甲基二烯丙基氯化铵（DDA）改性的AC作为载体，用于原位水热反应，由于静电吸引，使其能够与沸石组装。构建了它们各相的界面模型，揭示了结合力并模拟了结合过程。对复合材料的吸附性能和阻燃性能进行了评估。结果表明，DDA有效地改性了AC，使其在溶液中具有持久的正电荷。高硅和纯硅沸石显示出低负电荷甚至呈中性；难以通过静电吸引与改性AC结合。相反，使用了具有高铝含量和负电荷的LTA沸石，并采用了晶种诱导法。使用乙醇和超声分散来防止晶种和改性AC粉末的团聚，因此它们通过静电自组装。此外，延长了结晶时间，成功制备了具有高沸石负载量的复合材料。根据模型计算，DDA改性前后沸石与AC之间的结合能分别为324.97和1076.46 kcal/mol，DDA处理后它们之间的距离缩短了2.7 Å。结果，AC和沸石结合得更紧密，表现出更强的结合能。AC负载沸石提高了对高极性二氯甲烷的吸附容量，床层穿透时间增加了一倍。然而，用无机钠浸渍提高了复合材料中有机成分的反应活性，燃点略有降低。此外，静电自组装方法可以扩展到由成型AC制备LTA沸石/柱状AC复合材料，大大提高了其应用前景。
