A systematic study was conducted on the effect of the b-axis thickness on the adsorption/desorption properties of representative VOCs (toluene and dichloromethane) by varying the diffusion resistance over ZSM-5 nanosheets. ZSM-5 nanosheets with about 30 nm thickness along the b-axis (Z5-3) presented a 1.3-fold higher adsorption capacity (83.9 mg/g) and 27 % enhancement in breakthrough times for toluene (38 min) compared with conventional ZSM-5 (Z5-4). Dichloromethane adsorption capacity on Z5-3 (micropore volume of 0.12 cm3/g) was approximately 53 % higher than that on Z5-4 (micropore volume of 0.08 cm3/g) and only weekly correlated to the b-axis thickness due to its small molecular size. The adsorption isotherms and molecular dynamic simulations indicated that a shorter b-axis thickness enhanced the diffusion of toluene (3.9 × 10-5 cm2/s) and dichloromethane (7.2 × 10-5 cm2/s), as well as the toluene adsorption capacities over ZSM-5 samples. The toluene and dichloromethane physisorption mechanism was verified by adsorption kinetics. Additionally, the toluene and dichloromethane adsorption capacities of all samples decreased by about 33 % and 21 % at a relative humidity (RH) of 50 % at 298 K, respectively. This indicated that the structure of ZSM-5 samples did not significantly affect their hydrophobicity. Moreover, according to the competitive adsorption test results, toluene and dichloromethane underwent successive co-adsorption, competitive adsorption, and equilibrium adsorption. These findings are useful for designing high-performance and cost-effective zeolite adsorbents to efficiently remove volatile organic compounds from industrial sources.

中文翻译：

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沿 b 轴不同厚度的 ZSM-5 纳米片上 VOCs 吸附增强


通过改变 ZSM-5 纳米片上的扩散阻力，对 b 轴厚度对代表性 VOCs（甲苯和二氯甲烷）的吸附/解吸性能的影响进行了系统研究。与传统的 ZSM-5 （Z5-4） 相比，沿 b 轴 （Z5-3） 沿 b 轴 （Z5-3） 厚度约为 30 nm 的 ZSM-5 纳米片的吸附容量 （83.9 mg/g），甲苯的穿透时间 （38 min） 提高了 27%。Z5-3 上的二氯甲烷吸附能力（微孔体积为 0.12 cm3/g）比 Z5-4 上的二氯甲烷吸附量（微孔体积为 0.08 cm3/g）高约 53%，并且由于其分子尺寸小，仅与每周与 b 轴厚度相关。吸附等温线和分子动力学模拟表明，较短的 b 轴厚度增强了甲苯 （3.9 × 10-5 cm2/s） 和二氯甲烷 （7.2 × 10-5 cm2/s） 的扩散，以及 ZSM-5 样品上的甲苯吸附能力。通过吸附动力学验证了甲苯和二氯甲烷的物理吸附机制。此外，在 298 K 的相对湿度 （RH） 为 50% 时，所有样品的甲苯和二氯甲烷吸附能力分别下降了约 33% 和 21%。这表明 ZSM-5 样品的结构对其疏水性没有显著影响。此外，根据竞争吸附试验结果，甲苯和二氯甲烷经历了连续的共吸附、竞争吸附和平衡吸附。这些发现有助于设计高性能且具有成本效益的沸石吸附剂，以有效地去除工业来源中的挥发性有机化合物。