Abstract Clay-based composites are playing an increasingly important role in dye wastewater treatment. Herein, a modified carbon coated palygorskite (SPal@C) was firstly obtained by etching carbon coated palygorskite (Pal@C) under a small amount of hydrofluoric acid. Then, magnetic Co/SPal@C composites were prepared via impregnation and liquid phase chemical reduction. Adsorption performance of Congo red (CR) was investigated. The maximum adsorption capacity of the Co/SPal@C sample was 458.99 mg/g, which was higher than that of Pal (40.00 mg/g), SPal@C (81.97 mg/g) and Co sample (378.91 mg/g). The adsorption rate constant of the Co/SPal@C sample was up to 26.68 × 10−4 g/min∙mL, which was 3.9 times that of the Co sample (6.90 × 10−4 g/min∙mL). Besides, the magnetic Co/SPal@C adsorbent could allow for efficient magnetic separation from the solution and exhibited excellent regeneration ability. The relative standard deviation of the adsorption capacities for 6 cycles was 1.6%. SPal@C carrier weakened the ferromagnetism of CoNPs and also dispersed CoNPs stably, thus preventing the adsorbent agglomeration during cycling. Enhanced adsorption performance of Co/SPal@C was attributed to the synergistic effect between Co and SPal@C. The chemical interaction and electrostatic attraction between the SO3− group of CR and oxide species (Co3O4 and CoOOH) on the surface of CoNPs dominated the adsorption capacity. SPal@C can effectively disperse and stabilize CoNPs, thus providing more active adsorption sites. The results provided a new path for preparing high-efficiency and easily separable clay mineral-based adsorbents and broadened their application in dye wastewater treatment.

中文翻译：

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载有钴纳米颗粒的磁性碳包覆坡缕石用于去除水中的刚果红

摘要 粘土基复合材料在染料废水处理中发挥着越来越重要的作用。在此，首先通过在少量氢氟酸下蚀刻碳包覆坡缕石（Pal@C）获得改性碳包覆坡缕石（SPal@C）。然后，通过浸渍和液相化学还原制备磁性Co/SPal@C复合材料。研究了刚果红 (CR) 的吸附性能。Co/SPal@C样品的最大吸附量为458.99 mg/g，高于Pal（40.00 mg/g）、SPal@C（81.97 mg/g）和Co样品（378.91 mg/g） . Co/SPal@C 样品的吸附速率常数高达 26.68 × 10−4 g/min∙mL，是 Co 样品（6.90 × 10−4 g/min∙mL）的 3.9 倍。除了，磁性 Co/SPal@C 吸附剂可以有效地从溶液中磁分离，并表现出优异的再生能力。6 个循环的吸附容量的相对标准偏差为 1.6%。SPal@C 载体削弱了 CoNPs 的铁磁性并稳定分散了 CoNPs，从而防止了循环过程中吸附剂的团聚。Co/SPal@C 的吸附性能增强归因于 Co 和 SPal@C 之间的协同作用。CR 的 SO3− 基团与 CoNPs 表面的氧化物（Co3O4 和 CoOOH）之间的化学相互作用和静电引力主导了吸附能力。SPal@C 可以有效地分散和稳定 CoNPs，从而提供更多的活性吸附位点。