A new polymeric adsorbent for Cr(VI) ions based on an expanded poly(tetrafluoroethylene) (ePTFE) film was prepared by the combined use of the pretreatment with oxygen plasma and photografting of 2-(dimethylamino)ethyl methacrylate (DMAEMA). The grafting of DMAEMA was characterized by XPS and FR-IR spectroscopic measurements. The adsorption behavior of DMAEMA-grafted ePTFE (ePTFE-g-PDMAEMA) films was investigated as a function of the experimental parameters, such as the initial pH value, temperature, and grafted amount. The adsorption capacity and initial adsorption rate had the maximum values at the initial pH value of 3.0. On the other hand, the adsorption capacity became almost constant at temperatures higher than 30°C, although the adsorption rate increased over the temperature. The adsorption behavior obeyed the pseudo-second order kinetic model and well expressed by the Langmuir isotherm equation with higher correlation coefficients. These results indicate that the adsorption of Cr(VI) ions occurs through the electrostatic interaction between protonated dimethylamino groups on a grafted PDMAEMA chain and HCrO4- ions. Cr(VI) ions were successfully desorbed from Cr(VI)-loaded ePTFE-g-PDMAEMA films in the eluents, such as NaCl at 0.50 M, NH4Cl at 0.50 M, and NaOH at 1.0 mM, and ePTFE-g-PDMAEMA films were repeatedly used for adsorption of Cr(VI) ions without appreciable loss in the adsorption capacity. It should be noted that Cr(VI) ion adsorptivity with a high initial rate was conferred to the ePTFE films. The results obtained in this study emphasize that ePTFE-g-PDMAEMA films can be applied as an adsorbent for Cr(VI) ions.

中文翻译：

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甲基丙烯酸2-（二甲氨基）乙酯接枝膨胀聚（四氟）乙烯薄膜对六价铬离子的吸附和解吸行为

通过氧等离子体预处理和甲基丙烯酸2-（二甲氨基）乙酯（DMAEMA）的光接枝相结合，制备了一种基于膨胀聚（四氟乙烯）（ePTFE）膜的新型Cr（VI）离子聚合物吸附剂。DMAEMA 的接枝通过 XPS 和 FR-IR 光谱测量表征。DMAEMA 接枝的 ePTFE (ePTFE-g-PDMAEMA) 薄膜的吸附行为被研究为实验参数的函数，例如初始 pH 值、温度和接枝量。吸附容量和初始吸附速率在初始 pH 值为 3.0 时达到最大值。另一方面，吸附容量在高于 30°C 的温度下几乎保持不变，尽管吸附速率随温度升高而增加。吸附行为服从准二级动力学模型，并由具有较高相关系数的朗缪尔等温线方程很好地表达。这些结果表明，Cr(VI) 离子的吸附是通过接枝 PDMAEMA 链上的质子化二甲氨基与 HCrO4- 离子之间的静电相互作用发生的。Cr(VI) 离子成功地从洗脱液中负载 Cr(VI) 的 ePTFE-g-PDMAEMA 薄膜解吸，例如 0.50 M 的 NaCl、0.50 M 的 NH4Cl 和 1.0 mM 的 NaOH，以及 ePTFE-g-PDMAEMA 薄膜重复用于吸附 Cr(VI) 离子而吸附能力没有明显损失。应该指出的是，具有高初始速率的 Cr(VI) 离子吸附性被赋予 ePTFE 薄膜。