The present work considers an adsorptive removal of Indigo carmine (IC) dye onto nanotube carbon (CNTs). The pure CNTs were prepared via chemical vapor deposition (CVD) method utilizing methane gas as a carbon source at 1000 °C in a quartz tube. The morphology and surface chemical structure of the adsorbents were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption/desorption technique, and thermal gravity analysis (TGA). The parameters of the IC dye adsorption, such as initial concentration, contact time, pH, and mass-loaded adsorbent, were evaluated. The kinetic study confirmed that a pseudo-second-order model was best fitted to the adsorption data. The removal efficiency of adsorption onto pure and COOH-functionalized CNTs was 84% and 98.7% at 15 min, respectively. The equilibrium results were fitted well to the Langmuir isotherm model. The adsorption capacity of the CNT and COOH–CNT was 88.5 and 136 mg/g, respectively. The reusability of the adsorbents was studied, and after eight cycles, the efficiency decreased to 70%. Moreover, the density functional theory calculations confirmed that the functionalization of CNTs with COOH groups improves the adsorption properties of IC due to the formation of hydrogen-bonding interactions.

中文翻译：

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通过功能化的基于碳纳米管的吸附剂从水溶液中增强去除靛蓝胭脂红染料性能的研究：平衡，动力学和DFT研究

本工作考虑将靛蓝胭脂红（IC）染料吸附去除到纳米管碳（CNT）上。纯的CNT是通过化学气相沉积（CVD）方法在石英管中利用甲烷气体作为碳源在1000°C下制备的。通过扫描电子显微镜（SEM），X射线衍射（XRD），傅里叶变换红外光谱（FTIR），氮气吸附/解吸技术和热重分析（TGA）对吸附剂的形貌和表面化学结构进行了表征。评估了IC染料吸附的参数，例如初始浓度，接触时间，pH和大量吸附剂。动力学研究证实，伪二级模型最适合吸附数据。在15分钟时，纯净和COOH官能化的CNT的吸附去除率分别为84％和98.7％，分别。平衡结果非常适合Langmuir等温线模型。CNT和COOH-CNT的吸附容量分别为88.5和136 mg / g。研究了吸附剂的可重复使用性，经过八个循环后，效率降低到70％。此外，密度泛函理论计算证实，由于形成氢键相互作用，具有COOH基团的CNT官能化可提高IC的吸附性能。