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Novel Chemical Sensors For Indoor Air Quality

Novel Chemical Sensors For Indoor Air Quality. Musharraf Miah April 27, 2010. Outline. Introduction Emphasis of the project Experimental Section Results and Discussions Conclusions Acknowledgements. Introduction. Background.

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Novel Chemical Sensors For Indoor Air Quality

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  1. Novel Chemical Sensors For Indoor Air Quality Musharraf Miah April 27, 2010

  2. Outline • Introduction • Emphasis of the project • Experimental Section • Results and Discussions • Conclusions • Acknowledgements

  3. Introduction Background • We spend most of our time in indoor environment due to cold weather • Indoor air with formaldehyde is toxic and allergic for human health • Sources of formaldehyde are tobacco smokes, smokes from the wood stoves and fireplaces, • Formaldehyde can be released from furniture, cabinet, building materials, paints, dishwashing liquid, fabric softener, and so on • Canadian government has identified indoor air quality as an important health aspect • Health Canada has issued a legislation that limits the exposure to formaldehyde in indoor environments to less than 123 μg/m3 for 1 hour and less than 50 μg/m3 for 8 hours exposure

  4. Why polyaniline (PANI) • Most intensively studied conductive polymers • Simple synthesis and high environmental stability • Employed in electronic and optical application • Gas sensing application:H2S, NH3, methane, ethylene, CO, and acetylene Leucoemaraldine m = 0 Pernigraniline n = 0 Emaraldine n = m Emeraldine salt:

  5. Polyaniline (PANI) Polymer Approach Motivation For PANI Aniline Formaldehyde Concept: Carbinolamine intermediate

  6. Motivation For PANI (Continued) Oversimplified view: Overlap No overlap diphenyl amine

  7. Motivation for PANI (Continued): Conformational and electron delocalization changes that occur when formaldehyde reacts with diphenyl amine

  8. Emphasis of the project: • Electrical conductivity measurements were already performed • Optical detection of formaldehyde using fluorescence spectroscopy is being explored in this project • Polyaniline, poly (o-anisidine), and poly (2-ethyl aniline) are analyzed

  9. Liquid N2 flask Paraformaldehyde column 2 2 2 2

  10. Plunging formaldehyde : Liquid N2 flask Formaldehyde Column

  11. Results and Discussions Emission is maximum at 395 nm when excited at 295 nm Emission is maximum at 435 nm when excited at 310 nm Emission spectra of PANI in THF Emission spectra of PANI film

  12. Formalin =4.43 mM Polyaniline = 0.10 mM Formalin =44.33mM Polyaniline = 0.10 mM Intensity change =3% Intensity change = 14% Addition of 4.43 mM (44.3 equiv.) formalin solution into PANI (dissolved in THF) base solution Addition of 44.33 mM (443 equiv.) formalin solution into PANI (dissolved in THF) base solution

  13. Adding 1 equiv. of formalin Adding 1 equiv. offormalin Intensity change = 12% Intensity change = 32% Formalin response with PVPA-poly(o-anisidine) (0.5 fractional doping level) Formalin responses with H3PO4- PANI (0.3 fractional doping level)

  14. Adding 1 equiv. of acetaldehyde solution Intensity change = 6% Intensity change = 58% Maximum formaldehyde flow = 2.7 ppm Acetaldehyde response of poly2-ethylaniline (base) Formaldehyde response of 20% PVPA-doped poly(o-anisidine) film

  15. Conclusions • Demonstration for the detection of formaldehyde with polyaniline is presented in this work • 50% PVPA doped poly(o-anisidine) provided 32 % change upon addition to 1 equiv. formalin • poly(2-ethylaniline) gave 58% change upon addition to 1 equiv. acetaldehyde solution • Detection of formaldehyde via fluorescence quenching also observed from thin fims • Further detailed fluorescence studies are required to investigate the nature of fluorescence change upon the reaction between carbonyl species and polyanilines

  16. Acknowledgements • Especially grateful to my supervisor Dr. Gerardo Diaz- Quijada, who gave me the opportunity to work in his lab at NRC and always trained me up to professional standards • I would like present my gratitude to Prof. Edward Lai who accepted me as a CHEM 4908 student and always encourages me in learning • Special thanks to Dr. Bhavana Doere and Christy Maynard who always helped me in setting up instruments, discussing results and providing new ideas • Finally, I would like to thank the NRC ICT sector and the Steacie Institute for Molecular Science for its financial support

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