In the present work, the modified bentonites were prepared by the modification of bentonite with cetyltrimethylammonium bromide (CTAB), both cetyltrimethylammonium bromide and hydroxy-Fe cations and both cetyltrimethylammonium bromide and hydroxy-Al cations. X-ray diffraction (XRD), thermal analysis (TG-DTA), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and nitrogen adsorption/desorption isotherms were utilized to characterize the resultant modified bentonites. The modified bentonites were employed for the removal of phenol red dye from aqueous solution. Phenol red adsorption agreed well with the pseudo-second-order kinetic model. The equilibrium data were analyzed on the basis of various adsorption isotherm models, namely, Langmuir, Freundlich, and Dubinin‒Radushkevich models. The highest monolayer adsorption capacity of phenol red at 30°C derived from the Langmuir equation was 166.7 mg·g−1, 125.0 mg·g−1, and 100.0 mg·g−1 for CTAB‒bentonite, Al‒CTAB‒bentonite, and Fe‒CTAB‒bentonite, respectively. Different thermodynamic parameters were calculated, and it was concluded that the adsorption was spontaneous (∆G° 0), with increased entropy (∆S° > 0) in all the investigated temperature ranges.

中文翻译：

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水溶液中苯酚红在改性膨润土上的吸附

在目前的工作中，改性膨润土是通过用十六烷基三甲基溴化铵（CTAB）、十六烷基三甲基溴化铵和羟基铁阳离子以及十六烷基三甲基溴化铵和羟基铝阳离子改性膨润土制备的。利用 X 射线衍射 (XRD)、热分析 (TG-DTA)、红外光谱 (FT-IR)、扫描电子显微镜 (SEM) 和氮吸附/解吸等温线来表征所得改性膨润土。改性膨润土用于去除水溶液中的酚红染料。酚红吸附与拟二级动力学模型非常吻合。平衡数据基于各种吸附等温线模型进行分析，即 Langmuir、Freundlich 和 Dubinin-Radushkevich 模型。由朗缪尔方程得出的酚红在 30°C 的最高单层吸附容量分别为 166.7 mg·g-1、125.0 mg·g-1 和 100.0 mg·g-1，CTAB-膨润土、Al-CTAB-膨润土、和 Fe-CTAB-膨润土。计算了不同的热力学参数，得出的结论是吸附是自发的 (ΔG° 0)，在所有研究的温度范围内熵增加 (ΔS° > 0)。