生物质碳量子点的绿色制备及对Cu2+的检测

向日葵作为我国主要的油料作物之一，其秸秆是天然的纤维素材料，具有绿色无毒，成本低廉的优势，是制备生物质碳量子点的理想材料之一。近年来，由于含铜农药和化学肥料的不规范使用，大量含铜污染物被排放导致农田土壤和水环境中的铜含量远高于环境背景值。因此，迫切需要开发出一种选择性好、灵敏性强且对环境友好的Cu²⁺检测方法。碳量子点(CDs)是一种粒径小于10 nm的准球形荧光碳纳米材料，因其表面含有丰富的极性官能团，具有良好的水溶性而被广泛研究。与传统的半导体量子点(CdSe, CdTe)相比，CDs具有合成原料广泛、生物相容性好等优点。主要应用于生物成像、光催化、光电转化以及传感检测等领域。然而目前用于碳化合成CDs的前驱体大多为昂贵的化学品，且合成过程复杂污染环境，限制了CDs的大规模生产与应用。开发出一种生态友好，简单、廉价的CDs合成方法是很有意义的。本研究以废弃的向日葵秸秆为碳源，采用简便的水热法合成生物质碳量子点(S-CDs)作为荧光探针，用于检测识别Cu²⁺。通过对S-CDs的一系列光学性质分析与表征，鉴定出其表面官能团主要包括O—H, N...

Green Preparation of Biomass Carbon Quantum Dots for Detection of Cu2+

Sunflower is one of the main oil crops in China. Its straw is a natural cellulose material, which has the advantages of being green, non-toxic and low cost, and it is an ideal material for synthesising biomass carbon quantum dots. In recent years, due to the abuse of copper-containing pesticides and chemical fertilizers, many copper-containing pollutants have been discharged, resulting in the copper content in farmland soil and water environment being much higher than the environmental background value. Therefore, it is urgent to develop a Cu2+ detection method with good selectivity, high sensitivity and environmental friendly. Carbon quantum dots (CDs) are quasi-spherical fluorescent carbon nanomaterials with particle sizes less than 10 nm. Its surface contains abundant polar functional groups and has been widely studied for its good water solubility. Compared with traditional semiconductor quantum dots (CdSe, CdTe), CDs have extensive synthetic materials and good biocompatibility advantages. They are mainly used in biological imaging, photo catalysis, photoelectric conversion, sensor detection and other fields. However, most of the precursors of carbonized CDs synthesis are expensive chemicals, which have the disadvantages of a complex synthesis processes and environmental pollution, limiting the large-scale production and application of CDs. Therefore, developing an eco-friendly, simple and inexpensive CDs synthesis method is of great significance. In this study, waste sunflower straw was used as a carbon source, and a simple hydrothermal method was used to synthesize biomass carbon quantum dots (S-CDs) as fluorescent probes to detect Cu2+. Through a series of optical properties analysis and characterization of S-CDs, the surface functional groups of S-CDs mainly include O—H, N—H andC═N, among which abundant O—H can provide colloid stability, effectively control the morphology and particle size distribution of nanoparticles, thus improving the quantum yield (QYs) of S-CDs. ex=317 nm, em=456 nm, S-CDs have excellent optical performance and good optical stability in the pH range of 2.0~12.0, less affected by high salinity environment, QYs is about 8.42%, emitting blue fluorescence under UV analyzer irradiation at 365 nm. In addition, the fluorescence quenching effect of S-CDs induced by Cu2+ was further studied using the synthesized S-CDs as a fluorescence probes. The results showed that the prepared S-CDs were sensitive to Cu2+ in the concentration range of 0～10 μmol·L-1 with a good linear relationship (R2=0.971 4), and the detection limit (LOD) was as low as 167 nmol·L-1. In practice, the detection recoveries of Cu2+ in lake water are 96.18%～109.22%. In this study, a Cu2+ detection method based on fluorescent carbon quantum dots was introduced based on resource utilization of straw waste.