The increased use of color dyes in industry imposes a great threat to the environment. As such, developing cost-effective techniques for dye removal from wastewater attracted great attention. Earth materials, particularly those with large specific surface area (SSA) and high cation exchange capacity (CEC), were evaluated for their potential use for wastewater treatment. In this study, palygorskite, sepiolite, and clinoptilolite were evaluated for their removal of cationic dyes using safranin O (SO⁺) as a model compound. The CEC values of the materials played a key role in SO⁺ removal while other physicochemical conditions, such as temperature, equilibrium solution pH, and ionic strength, had less influence on SO⁺ removal. Sorbed SO⁺ cations were limited to the external surfaces of the minerals, as their channel sizes are less than the size of SO⁺ cation. Molecular dynamic simulations showed dense monolayer SO⁺ uptake on palygorskite due to its relatively large CEC value. In contrast, loosely packed monomer SO⁺ uptake was adopted on sepiolite for its large SSA and low CEC. Dense multilayers or admicelles of SO⁺ formed on zeolite surfaces. As such, for the best SO removal, palygorskite is better than sepiolite, though both are fibrous clay minerals.

中文翻译：

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纤维黏土矿物和沸石对脱色染料番红O的吸附去除

工业中彩色染料使用的增加对环境构成了巨大的威胁。因此，开发具有成本效益的从废水中去除染料的技术备受关注。对土壤材料，特别是那些具有大比表面积（SSA）和高阳离子交换容量（CEC）的材料，进行了废水处理的潜在用途的评估。在这项研究中，使用番红花O（SO ⁺）作为模型化合物，对坡缕石，海泡石和斜发沸石的阳离子染料去除效果进行了评估。材料的CEC值在SO ⁺去除中起关键作用，而其他物理化学条件（例如温度，平衡溶液pH和离子强度）对SO ⁺去除的影响较小。SO ⁺阳离子被限制在矿物的外表面，因为它们的通道尺寸小于SO ⁺阳离子的尺寸。分子动力学模拟表明，由于坡缕石的CEC值较大，因此单层SO ^+的致密吸收。相比之下，海泡石由于其大的SSA和低CEC而采用松散填充的单体SO ⁺吸收。在沸石表面上形成致密的SO ⁺多层或微粒。因此，为了达到最好的SO去除效果，坡缕石比海泡石更好，尽管两者都是纤维状粘土矿物。