Zhu Guocheng, Yin Jun
Hunan Provincal Key Laboratory of Shale Gas Resource Utilization, Hunan University of Science and Technology, Xiangtan, 411201, China.
Department of Civil and Environmental Engineering, University of Missouri, Columbia, MO, 65211, USA.
J Fluoresc. 2017 Jul;27(4):1233-1243. doi: 10.1007/s10895-016-2012-z. Epub 2016 Dec 29.
Natural organic matter is an important component of the aquatic environments, which has attracted wide attention to its influence of interaction with other pollutants. The present work aimed to investigate its fluorescence quenching (FQ) by coated metallic silver particles (AgNPs). In this work, using fluorescence spectroscopy in conjunction with UV-Vis spectroscopy and dynamic light scattering, the effect of coated AgNPs on fluorescence quenching intensity (FQI) of humic acid (HA) was assessed. In addition, the influence of electrolytes (NaCl, NaNO and CaNO) in the FQI was observed. Results showed that with AgNPs dosage increased (>1.17X10 mM), fluorescence quantum yield of HA gradually decreased, which implies that the FQ occurred. Furher observation showed that the FQ process followed both first-order and second-order Stern-Volmer functions. The FQ process was affected by the electrolytes: NaCl had an effect on reduction of FQI, possibly resulting from dissolution of AgNPs; Both of NaNO and Ca(NO) had an effect on the FQ of HA but Ca(NO) presented greater degree. As a result, the FQ degree of HA by alone electrolyte was listed in descent order as Ca(NO) > NaNO > NaCl, which also implies the subsequent experimental results, indicating the FQ degree of HA by mutual electrolytes as Ca(NO) + NaNO > Ca(NO) + NaCl > NaNO + NaCl.
天然有机物是水生环境的重要组成部分，其与其他污染物相互作用的影响已引起广泛关注。目前的工作旨在研究包覆金属银颗粒（AgNPs）对其荧光猝灭（FQ）的作用。在这项工作中，结合紫外可见光谱和动态光散射，使用荧光光谱法评估了包覆AgNPs对腐殖酸（HA）荧光猝灭强度（FQI）的影响。此外，还观察了电解质（NaCl、NaNO₃和Ca(NO₃)₂）对FQI的影响。结果表明，随着AgNPs用量增加（>1.17×10⁻³ mM），HA的荧光量子产率逐渐降低，这意味着发生了荧光猝灭。进一步观察表明，荧光猝灭过程遵循一级和二级Stern-Volmer函数。荧光猝灭过程受电解质影响：NaCl对降低FQI有影响，可能是由于AgNPs的溶解；NaNO₃和Ca(NO₃)₂都对HA的荧光猝灭有影响，但Ca(NO₃)₂的影响程度更大。因此，单独电解质对HA的荧光猝灭程度按Ca(NO₃)₂>NaNO₃>NaCl的顺序排列，这也暗示了后续实验结果，即混合电解质对HA的荧光猝灭程度为Ca(NO₃)₂ + NaNO₃>Ca(NO₃)₂ + NaCl>NaNO₃ + NaCl。
