Effects of Different Substituents on Three Dimensional Fluorescence Properties of BTEX
WANG Bi1, 2, XI Hong-bo2, ZHOU Yue-xi1, 2*, CHEN Xue-min1, FU Xiao-yong1
1. School of Environment And Municipal Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
2. Research Center of Water Pollution Control Technology, Chinese Research Acaemy of Environmental Sciences, Beijing 100012, China
Abstract:Three-dimensional fluorescence excitation-emission has been widely used to characterize dissolved organic matter in municipal wastewater, lakes and rivers. However, As one of the most important pollutants in petrochemical wastewater, the fluorescence characteristics of BTEX are rarely reported. In this paper, the fluorescence spectra of 14 typical BTEX at different concentrations were studied by F-7000 fluorescence spectrometer, and the relationship between the characteristics of three dimensional fluorescence spectra and their structural characteristics was discussed. The results showed that the structure, location and number of the substituents will affect the fluorescence characteristics of BTEX. Fluorescence peaks of benzene, toluene, ethyl-benzene, n-propylbenzene, cumene, xylene and 1,2,4-trimethyl benzene located at λех/λеm=205~215/280~295 nm. A fluorescence peak of styrene located at λех/λеm=230/345 nm. Two fluorescence peaks of phenol located at λех/λеm=220/300 nm, 270/295 nm. Two fluorescence peaks of aniline located at λех/λеm=235/335 nm, 280/335 nm. Chlorobenzene had a fluorescence peak locating at λех/λеm=215/290 nm, and no obvious fluorescence peaks of nitrobenzene were found. On the conditions of 1 mg·L-1 compared with benzene, the fluorescence intensity (FI) of toluene and ethylbenzene were increased by 10.62 and 9.45 times, with λех red shifting 5 nm, and intensity of fluorescence peaks of 1,2,4-trimethylbenzene, three kinds of xylene enhancement ratio were 5.49(above), 4.87, 2.14, 1.33. This is mainly due to the carbon atoms of substituents which directly connected with benzene-ring expanded the rigid plane. This showed the number of carbon atoms that non coplanar and coplanar of alkyl substituents in benzene will affect the fluorescence properties of matter. When the vinyl group of styrene expanded the rigid plane, the unsaturated double bond reduced the energy required for its excitation, the fluorescence intensity of 10 mg·L-1 ethylbenzene same with the concentration of 0.002 mg·L-1 styrene, the λех red shifting 20 nm compared with ethylbenzene relatively. Electron donating substituents,—OH and —NH2 can enhance the electron density of conjugated structure of the benzene-ring. The P orbital of n electron with the benzene formation of P—π conjugated system structure, rigid plane expansion, the intensity of fluorescence peaks increased with fluorescence spectrum redshift. On the contrary, the —NO2 and —Cl groups substances n→π* transition belonged to the forbidden transition, the less number of excited state molecules, while the intersystem crossing was stronger than π*→S1. Experimental results for weak fluorescence or no fluorescence were consistent with the theory.
王 碧,席宏波,周岳溪,陈学民,伏小勇. 不同取代基对苯系物三维荧光光谱特征的影响[J]. 光谱学与光谱分析, 2017, 37(12): 3763-3770.
WANG Bi, XI Hong-bo, ZHOU Yue-xi, CHEN Xue-min, FU Xiao-yong. Effects of Different Substituents on Three Dimensional Fluorescence Properties of BTEX. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2017, 37(12): 3763-3770.
[1] HE Qin-cong, CHENG Guo-fei, REN Yuan, et al(何勤聪, 成国飞, 任 源, 等). Chemical Industry and Engineering Progress(化工进展),2009, 28(6): 1080.
[2] LI Qing, WANG Zhi-guo, DING Shi-bing(李 庆, 王志国, 丁士兵). Pollution Control Technology(污染防治技术), 2016, 29(2): 53.
[3] ZHOU Wen, WANG Lian-sheng(周 雯, 王连生). Environmental Monitoring in China(中国环境监测), 2006, 22(1): 91.
[4] JIANG Yang, FANG Li-ping, YANG Gang, et al(姜 洋, 房丽萍, 杨 刚, 等). Environmental Chemistry(环境化学), 2015, 34(9): 1611.
[5] Lenhardt L, Dramicanin M D. Journal of Luminescence, 2016, 170: 136.
[6] Farmaki E G, Thomaidis N S, Efstathiou C E. International Journal of Environmental Analytical Chemistry, 2010, 90(2): 85.
[7] Liu H, Song Q, Wang H. Structural Chemistry, 2016, 27(4): 1175.
[8] Schwarz F P, Wasik S P. Anal. Chem., 1976, 48(3): 524.
[9] ZHOU Yun, LI Jun, CHEN Fei, et al(周 昀, 李 军, 陈 飞, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2016, 36(7): 2169.
[10] XU Jin-gou, WANG Zun-ben(许金钩, 王尊本). Fluorescence Analysis Methond(荧光分析法). Beijing: Science Press(北京: 科学出版社), 2006. 49.
[11] ZHU Tuo, CHEN Guo-qing, YU Rui-peng, et al(朱 拓, 陈国庆, 虞锐鹏, 等). Opto-Electronic Engineering(光电工程),2005, 32(4): 24.
[12] James Jr D I, Stanley R C. Spectrochemical Analysis(光谱化学分析). Translated by ZHANG Han-qi, WANG Fen-di, SHI Wen(张寒琦, 王芬蒂, 施 文,译). Changchun: Jilin University Press(长春: 吉林大学出版社), 1996. 360.
[13] ZHANG Yan-you, PAN Ren-man(张炎有, 潘仁满). Journal of Higher Correspondence Education·Natural Sciences(高等函授学报·自然科学版),1996, (1): 7.
[14] ZHANG Wen-wei, XIN Chang-bo, LI Xiao-hui, et al(张文伟, 辛长波, 李晓辉, 等). Chinese Journal of Analysis Laboratory(分析实验室), 2000, 16(5): 37.