Application Of Fluorescent Carbon Quantum Dot Composite Film In VOCs Gas Detection

With the increasing consumption of organic solvents in chemical and pharmaceutical industries,the environment pollution of volatile organic compounds（VOCs）has become an urgent problem.Therefore,the rapid-visual detection method is of great significance in the analysis of VOCs.Based on the fluorescence quenching/enhancement mechanism of carbon quantum dots（CQDs）,a series of green CQDs@carboxymethyl cellulose composite film（CQDs@CMC film）were prepared in this study.In the typical-targeted pollutants（toluene and cyclohexane）detection application,a fluorescence spectroscopy method was established which could achieve the high sensitivity and strong specificity detection.The mainly conclusions were as follows:1)The fluorescence spectrometric detection method for toluene:A kind of hydrophobic Lmi/Bet CQDs@CMC film was prepared and characterized with imidazole/betaine CQDs and porous carboxymethyl cellulose composite film as raw materials.The toluene detection performance was studied,and the recognition mechanism was explored.The results showed that toluene enhanced the fluorescence of Lmi/Bet CQDs@CMC films.The fluorescence intensity of composite films was proportional to toluene concentration when the toluene concentration ranged from 200 to 2200 ppm.The detection limit of toluene was 1.169 ppm,which provides a theoretical basis for the detection of toluene by fluorescence spectrometry.2)Detection of toluene by Glycerol/Betaine CQDs composite film（Gly/Bet CQDs@CMC film）:Gly/Bet CQDs@CMC film was prepared with glycerol/betaine CQDs and carboxymethyl cellulose composite film to achieve a high sensitivity and strong specificity detection of toluene.The results showed that,the fluorescence intensity of Gly/Bet CQDs@CMC film was proportional to toluene concentration when toluene concentration ranges from 200 to 1400 ppm.The detection limit of toluene was 0.452 ppm,which meets the requirement of toluene emission concentration detection.3)Detection of cyclohexane gas byβ-cyclodextrin/L-phenylalanine CQDs composite films:β-CD/L-Phe CQDs@CMC films was prepared withβ-cyclodextrin/L-phenylalanine CQDs and carboxymethyl cellulose composite films.It was found that the fluorescence ofβ-CD/L-Phe CQDs@CMC films was quenched obviously by cyclohexane gas.When the concentration of cyclohexane gas ranged from 100 mg·m^-3 to 1000 mg·m^-3,the fluorescence intensity of the composite film was inversely proportional to the concentration of cyclohexane gas,and the detection limit was 1.079 mg·m^-3.Theβ-CD/L-Phe CQDs@CMC film is an efficient detection for industrial waste gas emissions,and is also useful for workshop individual protection.