Abstract Mesocellular foam silica was prepared by a hydrothermal synthesis protocol. The surface and pore structure of mesocellular foam silica were characterized by low temperature nitrogen adsorption isotherms, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy. The methylene blue was adsorbed by the synthetic mesocellular foam silica; the optimized adsorption conditions were evaluated and the maximum adsorption capacity of methylene blue by mesocellular foam silica was determined to be 215.5 mg g−1. The kinetics of the adsorption of methylene blue by mesocellular foam silica were in accordance with a quasi-second-order kinetic equation. The results were analyzed by Langmuir and Freundlich adsorption isotherm models. The adsorption of methylene blue on mesocellular foam silica was shown to follow the Freundlich adsorption isotherm model. The Gibbs free energy change during adsorption showed that this process was spontaneous. The enthalpy change in the process was –28.868 J·mol−1 K−1, indicating that the adsorption is exothermic. The negative value of entropy –49.296 J·mol−1 K-1 shows that the system disorder decreases due to adsorption.

中文翻译：

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亚甲基蓝水溶液在中孔泡沫二氧化硅上的吸附特性：平衡、动力学、等温线和热力学表征

摘要 采用水热合成法制备了中孔泡沫二氧化硅。通过低温氮吸附等温线、X 射线衍射、扫描电子显微镜、透射电子显微镜和傅里叶变换红外 (FT-IR) 光谱对中孔泡沫二氧化硅的表面和孔结构进行了表征。亚甲蓝被合成的中孔泡沫二氧化硅吸附；对优化的吸附条件进行了评估，确定中孔泡沫二氧化硅对亚甲蓝的最大吸附容量为 215.5 mg g-1。中孔泡沫二氧化硅对亚甲基蓝的吸附动力学符合准二级动力学方程。结果通过 Langmuir 和 Freundlich 吸附等温线模型进行分析。亚甲基蓝在中孔泡沫二氧化硅上的吸附显示遵循 Freundlich 吸附等温线模型。吸附过程中的吉布斯自由能变化表明该过程是自发的。该过程中的焓变为–28.868 J·mol-1 K-1，表明吸附是放热的。熵为负值–49.296 J·mol-1 K-1 表明系统无序度因吸附而减少。