PA6基碳点的水热法制备及以其为荧光探针的pH检测

Preparation of PA6-Based Carbon Dots by Hydrothermal Method and its Application

摘要:

为探究聚己内酰胺（PA6）废弃物的回收利用新技术，本研究以PA6和均苯四甲酸为原料，采用水热法制备了氮元素掺杂PA6基碳点（6CDs），并对其制备条件进行了优化。采用荧光光谱仪、TEM、XPS及FTIR对制备的6CDs进行了表征，并探究了以6CDs为荧光探针的pH检测。结果表明，6CDs的较优制备条件为50 mL反应釜中，PA6的用量为3.0 g、均苯四甲酸的用量为0.3 g、反应温度为260℃、反应时间为18 h。较优条件下制备的6CDs为球形结构，平均粒径为4.2 nm，表面含有—NH2、—OH及—COOH。6CDs在365 nm紫外灯的照射下发射出明亮的蓝色荧光，其荧光具有激发波长依赖性，最佳激发光波长为330 nm，最佳发射光波长为450 nm，荧光量子产率为25.3％，6CDs对常见金属阳离子几乎不响应，体系的抗金属离子干扰能力强，光学性能稳定。同时，6CDs的荧光强度随着pH值的增大而增大，且分别在pH=1.3-4.0和pH=4.0-11.9的范围中荧光强度与pH值呈线性相关，R2分别为0.9986和0.9985，线性相关程度较高，因此可用于pH（1.3-11.9）的检测。

Abstract:

In order to explore the new recycling technology of polycaprolactam(PA6) waste, Nitrogen doped PA6-based carbon dots(6CDs) was prepared by hydrothermal method with polycaprolactam(PA6) and pyromellitic acid as raw materials. The preparation conditions were optimized. 6CDs prepared were characterized by fluorescence spectrometer, TEM, XPS and FTIR. The pH detection using 6CDs as fluorescent probe was explored. The results showed that the better conditions for the preparation of 6CDs were as follows: In a 50 mL reactor, the dosage of PA6 was 3.0 g, the dosage of pyromellitic acid was 0.3 g, the reaction temperature was 260℃, and the reaction time was 18 h. 6CDs prepared under better conditions were spherical with an average particle size of 4.2 nm, its surface contained —NH2, —OH and —COOH. 6CDs will emit bright blue fluorescence under the irradiation of 365 nm UV light, and its fluorescence is excitation wavelength dependent, the best excitation wavelength is 330 nm, the best emission wavelength is 450 nm, the fluorescence quantum yield is 25.3%, 6CDs is almost not responsive to common metal cations, and the system has strong resistance to metal ion interference, the optical properties of 6CDs are stable. The fluorescence intensity of 6CDs increases with the increase of pH value, within the scope of pH=1.3-4.0 and pH=4.0-11.9, the fluorescence intensity is linearly correlated with pH value, and the R2 values are 0.9986 and 0.9985 respectively. The degree of linear correlation is high. Therefore, 6CDs can be used for the detection of pH (1.3-11.9).