农业工程学报2025，Vol.41Issue(2)：242-250,9.DOI:10.11975/j.issn.1002-6819.202407078
基于氮掺杂石墨烯量子点的荧光法检测水中的氨氮含量
Detecting ammonia nitrogen in water using fluorescence with nitrogen-doped graphene quantum dots
摘要
Abstract
Ammonia nitrogen(NH3-N)can serve as one of the key indicators of water quality.However,the NH3-N level can rapidly increase over a short period in intensive aquaculture,due to farming density,feeding modes,and water renewal frequency.The high-level NH3-N-induced stress can cause eutrophication damage to aquatic animals and even mortality.Therefore,it is crucial to detect the NH3-N in water,in order to prevent water quality deterioration for the safety of aquatic life.Particularly,the current detection of NH3-N is often complex,costly,time-consuming,and limited in detection range.This study aims to propose an accurate and rapid detection of high NH3-N concentrations in water.A nitrogen-doped graphene quantum dots(N-GQDs)fluorescent probe was then constructed to detect the NH3-N content in water.Firstly,the morphology and size distribution of the N-GQDs were examined using transmission electron microscopy(TEM).The lattice spacing of the N-GQDs was observed to be 0.20 nm,corresponding to the(100)lattice plane of the graphite structure.X-ray diffraction(XRD)analysis showed the diffraction peaks at 19°and 29°were attributed to the(101)and(002)crystal planes of graphene,respectively.Fourier transform infrared spectroscopy(FT-IR)analysis demonstrated the presence of carboxyl groups(-COOH)on the surface of the N-GQDs.The N1s spectrum of X-ray photoelectron spectroscopy(XPS)indicated that the nitrogen was doped in the GQDs in the form of pyrrole nitrogen.The characterization results from TEM,FT-IR,XPS,and XRD confirmed that the N-GQDs with a graphene crystal structure were successfully synthesized.Additionally,the optical properties were performed on the N-GQDs fluorescent probe.Specifically,the N-GQDs exhibited an absorption peak at 320 nm in the UV-Vis spectrum,due to the π→π* transition within the C=C structure.Meanwhile,the fluorescence spectra showed that the optimum excitation and emission wavelengths of the N-GQDs were 350 and 450 nm,respectively.The aqueous solution of N-GQDs shared a pale yellow under daylight and then emitted blue fluorescence under a 360 nm UV lamp.The N-GQDs fluorescent probe showed a good linear response(R2=0.99)to NH3-N concentration in the range of 0-9.0 mmol/L under the optimal experimental conditions(pH=7,N-GQDs concentration 0.8 mg/mL),with the detection limit concentration of 43.8 µmol/L and response time of 2 min.Furthermore,the stability,repeatability,and anti-interference properties of the fluorescent probe were carried out.The probe exhibited the excellent stability,and anti-interference properties against Na+,Hg+,Ag+,K+,Pb2+,Ca2+,Cd2+,and Cu2+.The fluorescence intensity of the probe still recovered to 77%of the initial value after three uses,indicating that the probe has good reproducibility.The response mechanism of the N-GQDs fluorescent probe to NH3-N was analyzed by UV-Vis,FT-IR,and fluorescence lifetime decay analysis and Stern-Volmmer equation.The carboxyl groups on the surface of the N-GQDs exhibited electron-accepting properties.The pyrrole nitrogen doped into the GQDs carried a slight positive charge.Ammonia acted as a typical electron donor,due to the lone pair of electrons on the nitrogen atom.Therefore,it inferred that the photo-induced electron transfer occurred between ammonia and the N-GQDs,resulting in the dynamic quenching of N-GQDs fluorescence.Finally,the N-GQDs fluorescent probe was used to determine the NH3-N in drinking,tap,and aquaculture water,with the recoveries of the spiked assay ranging from 75.03%to 128.16%and relative standard deviations(RSD)(n=3)lower than 13.53%.Consequently,the N-GQDs fluorescent probe also shared the potential applications in the detection of NH3-N in water.关键词
量子点/荧光法/氨氮/水环境Key words
quantum dots/fluorescence method/NH3-N/aqueous environment分类
轻工纺织引用本文复制引用
张佳然,于杰,赵天驰,岳云涛,王聪..基于氮掺杂石墨烯量子点的荧光法检测水中的氨氮含量[J].农业工程学报,2025,41(2):242-250,9.基金项目
北京建筑大学青年科研创新专项(X23023) （X23023）
十四五国家重点研发计划项目(2022YFD2001702) （2022YFD2001702）
北京市科协金桥工程种子资金项目(Z23151) （Z23151）
