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Abstract：
This article presents a one-step ultrasonication technique for generating biomass carbon dots (BCDs) from neem bark (Azadirachta indica) powder. The BCDs were characterized using modern techniques such as UV-Vis, FTIR, Raman, XRD, HRTEM, FESEM, EDAX, and Zeta potential analyses. Unlike traditional nanocomposite bed systems, this study utilized BCDs as a liquid-phase adsorbent for the regenerative adsorption of the environmentally harmful dye, methylene blue (MB), through an in-situ precipitation reaction. This involved the formation of BCDs-MB adduct via an electrostatic mechanism. The adsorption capacity and percentage of removal were remarkable at 605 mg g-1 and 64.7% respectively, exceeding various solid-based adsorption methods in the literature. The Langmuir isotherm and pseudo-second-order kinetics model provided an excellent fit for this system. The calculated thermodynamic parameter, Gibbs free energy change (ΔG) was negative, indicating a spontaneous, exothermic, and physisorption-based mechanism. The regenerative capacity of our system was further demonstrated by successfully extracting and recovering the MB dye (64%) using ethyl alcohol as the solvent. This method provides an efficient means of recovering valuable cationic organic dye compounds from contaminated environments.
摘要：
本文介绍了一种一步超声处理技术，用于从印度印树皮（Azadirachtaindica）粉末中生成生物质碳点（BCD）。BCD的特征是使用现代技术，如紫外-可见，FTIR,拉曼,XRD,HRTEM,FESEM，EDAX,和Zeta电位分析。与传统的纳米复合床系统不同，这项研究利用BCDs作为液相吸附剂再生吸附对环境有害的染料，亚甲蓝(MB),通过原位沉淀反应。这涉及通过静电机制形成BCD-MB加合物。吸附容量和去除率分别为605mgg-1和64.7％，超过了文献中的各种固体吸附方法。Langmuir等温线和伪二阶动力学模型为该系统提供了极好的拟合。计算的热力学参数，吉布斯自由能变化(ΔG)为负，表明自发的，放热,和基于物理吸附的机制。通过使用乙醇作为溶剂成功提取和回收MB染料（64％），进一步证明了我们系统的再生能力。该方法提供了从污染环境中回收有价值的阳离子有机染料化合物的有效手段。
