The inadequate handling and uncontrolled discharge of organic dyes into aquatic environments can result in elevated toxicity levels and have adverse effects on both human health and the overall ecosystem. The present work investigated the photodegradation efficiency of the ZnO-SnO@chitosan nanocomposite (NC) for Rhodamine B (RhB) under ultraviolet (UV) irradiation. The ZnO-SnO@chitosan nanocomposite (NC) was synthesized via a simple, eco-friendly, and less energy-intensive route, i.e., the co-precipitation method. The synthesized NC was extensively characterized using X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), UV–Vis spectroscopy, Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS). The chitosan-modified nanocomposite (NC) exhibits a moderate surface area of 79 m/g with a low band gap value of 2.72 eV. The photodegradation process depended on operational parameters, such as pH, irradiation time, temperature, dye concentration, and dosage of the photocatalyst. The degradation data of RhB dye was interpreted through a kinetic model, and the data agreed well with the pseudo-first-order kinetics. The rate constant values deciphered from the kinetic model were found to fall in the range of 0.0281–0.0182 min for 25–100 mg/L of dye concentration, suggesting that the synthesized photocatalysts facilitate the dye mineralization process by reducing the activation energy barrier. The interpretation of the reaction intermediates was accomplished with the help of a GC-MS profile to understand the underlying reaction mechanism. The photodegradation potential of the synthesized NC was explored for individual dyes such as RhB, MB and CV and the mixed dye system (RhB+MB+CV). The NC performs better for individual dyes (RhB, CV, and MB), and the degradation performance diminished slightly in the case of mixed dye solution. The reusability study of the synthesized nanocomposites portrayed the successful utility of the recycled NC up to four times without any significant loss in the degradation capacity, thus making the overall degradation process economical and sustainable. The –factor (a green chemistry metric) study infers that the NC synthesis process imposes no significant threat to the environment and can be safely used in wastewater treatment.

中文翻译：

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植物叶提取物辅助环保制造 ZnO-SnO2@壳聚糖，用于紫外线诱导增强罗丹明 B 单一和三元混合物的光降解

有机染料处理不当和不受控制地排放到水生环境中可能会导致毒性水平升高，并对人类健康和整个生态系统产生不利影响。目前的工作研究了 ZnO-SnO@壳聚糖纳米复合材料 (NC) 在紫外线 (UV) 照射下对罗丹明 B (RhB) 的光降解效率。ZnO-SnO@壳聚糖纳米复合材料（NC）是通过一种简单、环保且能耗较低的路线，即共沉淀法合成的。使用 X 射线衍射 (XRD)、傅里叶变换红外光谱 (FTIR)、紫外-可见光谱、Brunauer-Emmett-Teller (BET) 分析、场发射扫描电子显微镜 (FE-SEM) 对合成的 NC 进行了广泛表征。能量色散 X 射线 (EDX) 光谱和紫外-可见漫反射光谱 (UV-Vis DRS)。壳聚糖改性的纳米复合材料 (NC) 具有 79 m/g 的中等表面积和 2.72 eV 的低带隙值。光降解过程取决于操作参数，例如 pH、照射时间、温度、染料浓度和光催化剂的剂量。通过动力学模型解释了RhB染料的降解数据，数据与准一级动力学吻合良好。从动力学模型中解析出的速率常数值在 25–100 mg/L 的染料浓度下落在 0.0281–0.0182 min 的范围内，这表明合成的光催化剂通过降低活化能垒来促进染料矿化过程。反应中间体的解释是在 GC-MS 分析的帮助下完成的，以了解潜在的反应机制。探索了合成 NC 对 RhB、MB 和 CV 等单独染料以及混合染料系统 (RhB+MB+CV) 的光降解潜力。NC 对于单一染料（RhB、CV 和 MB）表现更好，而在混合染料溶液的情况下，降解性能略有下降。合成纳米复合材料的可重复使用性研究表明，回收的NC可成功使用四次，而降解能力没有任何显着损失，从而使整个降解过程经济且可持续。–factor（绿色化学指标）研究表明，NC 合成工艺不会对环境造成重大威胁，可以安全地用于废水处理。