苯酚三维荧光光谱特征参数影响因素的研究

用三维荧光光谱法研究了不同离子浓度,pH值对苯酚荧光光谱特征参数的影响,并探讨了腐殖酸对苯酚的荧光猝灭效应.结果表明,天然水中9种常见离子Na~+、Mg~(2+)、Ca~(2+)、K~+、NH_4~+、Cl~-、HCO_3~-、SO_4~(2-)、HPO_4~(2-)对苯酚的荧光光谱形状和荧光强度基本无影响;NO_3~-的存在会使苯酚的荧光强度发生变化,荧光强度随着NO_3浓度增大而减小.苯酚在酸性和碱性条件下的存在形式不同,致使pH值对其荧光光谱特征参数影响较大:在酸性条件下,荧光强度基本保持不变;在碱性条件下,由于羟基的电离使荧光强度很弱.腐殖酸的存在使苯酚发生荧光猝灭,采用Stem-Volmer方程修正式对实验猝灭结果进行拟合,得到的拟合结果较好,相关系数为0.9995.

Influence factors on characteristic parameters of three-dimensional fluorescence spectra of phenol

Characteristic parameters of phenol were investigated at different ion concentration and pH values by three-dimensional fluorescence spectra method. In the meantime, the effect of fluorescence quenching brought by humic acid was also explored. Results showed that nine kinds of ions usually existing in natural water including Na+、Mg2+、Ca2+、K+、NH4+、Cl-、HCO3-、SO42-、HPO42- had no effect on the shape of spectra and fluorescence intensity of phenol. However, the presence of NO3- caused the changes of fluorescence intensity, which decreased with the increasing concentration of NO3-. The impact of pH was significant because phenol had different forms in acidic and alkali conditions. The fluorescence intensity remained unchanged in acidic condition; in contrast, only a weak fluorescence signal was found in the alkali condition.The latter phenomena can be explained by the ionization of hydroxyl. In addition, the presence of humic acid may cause the fluorescence quenching. Finally, Stern-Volmer equation was used to fit the quenching results, and good results had been obtained with relative coefficient of 0.9995.