Undergraduate research presentation clba (1)


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The investigation of photo-oxidation of gas phase cyclohexane was an experimental study used to determine how the concentration of cyclohexane in a bulk flow influent to a photcatalytic reactor affects the rate of degradation. In addition, a secondary set of tests will be conducted to aide in obtaining data for determining the effect of particle size on degradation

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  • By it simplest description, photocatalysis denotes the acceleration of a photoreaction by the action of a catalysts.If we split the term photcatalysis into its to constituent parts, we are left with Photo and catalysis.Photo is defined as light, radiant energy, of or pertaining to light, while catalysis is defined as the action of a catalyst; as well as the increase or decrease of the rate of a chemical reaction.Many of the phenomena related to photochemistry and catalysis differ qualitatively by nature, placing them in different fields which has lead to multiple definitions for photocatalysis and consequently the development of glossary of terms and definitions.
  • Talk Aboutorganic Contaminants and VOCs– what they are, examples, Potential Health Effects
  • There are many products we use and day-to-day examples of photocatalysis that most of us never acknowledge and take for granted.If you have ever wondered what that small stamp is in the corner of your windows of a car, most likely, it’s the brand and identifier of a self-cleaning glass company. Pictured here is Pilkington Ativ self-cleaning glass used in a mercedes-Benz. Pilkington claims to be the first company to use a photocatalytic coating on its glass which breaks down organic dirt w/ sunlight, and is then washed away by rain.Many air purifiers sanitize air through filters, but when Titantium Oxide is applied with Sunlight, like the Air Oasis Photocatalytic UV Air Purifier pictured, it kills surface mold, bacteria, viruses, and degrade harmful gaseous Volatile Organic Compounds (or VOCs)Water TreatmentCoated Tiles – HospitalsAnti Fogging glassBuilding Material Coating
  • Undergraduate research presentation clba (1)

    1. 1. An investigation of gas-phase photocatalytic oxidation of cyclohexane in air on TiO2 A seminar prepared for SEAS Undergraduate Research Forum November 17, 2009 By Samuel T. Kurachek Miami University Paper and Chemical Engineering Department Advisor: Dr. Catherine Almquist
    2. 2. What is the phenomenon known as photocatalysis? Light; radiant energy; of or pertaining to light Photo Catalysis The action of a catalyst; the increase or decrease of the rate of a chemical reaction  It denotes the acceleration of a photoreaction by the action of a catalyst  It also refers to a general label to indicate that light and a substance (Catalyst or initiator) are necessary entities to influence a reaction
    3. 3. Application to Pollution Prevention  The process of photocatalytic oxidation has undergone numerous studies for its potential application to industry ◦ Degradation of organics in water and in air ◦ Disinfection of water ◦ Self-cleaning surfaces ◦ Organic synthesis
    4. 4. Everyday examples and Applications of photocatalysis using TiO2  SelfCleaning Glass  Air purifiers   Water Treatment Anti-fogging glass   Coated Tiles Building Material Coating
    5. 5. Further Examples            . Printing ink • Antimicrobial Coatings: Paint Activity of TiO2 results in thin coatings of Plastics the material to which its applied to exhibit self-cleaning and disinfecting Paper properties with exposure to UV radiation Synthetic fibers Rubber Painting colors and crayons Ceramics Electronic Components Cosmetics Condensers
    6. 6. Mechanism for Gas Phase Photocatalysis with TiO2 hVB RHOH •RH RH2 (Alcohol or Ketone Intermediate)
    7. 7. Research Goals Focus on gas phase photo-oxidation of cylcohexane in air on TiO2 catalyst Cyclohexane (C6H12) 1) Determine the effect of cyclohexane concentration on the rate of cyclohexane degradation via photocatalysis 2) Determine the effects of TiO2 brand and particle size on the photoactivity of TiO2.
    8. 8. Experimental Apparatus Aluminum box to contain light Vent To Hood 400 W xenon lamp TiO2 – coated glass beads Air inflow from MFC Bulk Flow of Air and Cyclohexane (vap.) into Photocatalytic Reactor Acetone-filled Impinger Air Cyclohexane Vapor Diffusing into Bulk Flow of Air Ceramic cylinders to distribute air Cyclohexane (Liq.) Cyclohexane Vapor Generator
    9. 9. Experimental Procedure Photocatalytic Reactor • Mass Flow Controller Set Airflow rate at Experiment 100 ccpm • Varied Temp. 1 Diffusion Cell • Mass Flow Controller Set Airflow rate at 50 Experiment ccpm • Varied Path L. 2 Diffusion Cell Miget Impinger Bubbler Sample CO2+ H2O Cyclohexane Vapor in air AcetoneTrap VOC Calibration and Analysis HewlettPackard HP 5890 GC
    10. 10. Safety First! Use safety glasses/goggles and gloves, have close-toed shoes, and use caution when working with volatile organics  Tell someone (professor, graduate student, other student) that you are working in the laboratory so that someone knows what you are doing and when.  Never do experimental work without someone else in the building.  If something does go wrong, first contact someone for help and then refer to the safety sheets located in the white binder inside the door of the lab – Chemicals/gases being used: Cyclohexane, Acetone, Hydrogen Gas, Helium Gas (Benzene was also in the lab work area used by another student)
    11. 11. Effect of inlet cyclohexane concentration  Although the inlet concentration of cyclohexane varied from 400 ppm – 650 ppm, the rate at which cyclohexane degraded was approximately 200 ppm/min or 0.035 mg/min.  Langmuir-Hinshelwood Kinetics often models photocatalytic oxidation systems well: dC / dt = kC / (1+KC) NOTE: When KC >> 1, then dC/dt = k/K When KC << 1, then dC/dt = kC Preliminary data suggests that our system was operated such that KC >> 1, and that the ratio of k / K is ~200 ppm/min. Thus, to see an effect of inlet concentration, a cyclohexane concentration of < 10 ppm would need to be fed to the reactor.
    12. 12. Effect of TiO2 particle size – To Be Completed  Hypothesis is that the competing effects of increasing specific surface area and decreasing light absorption as particle size decreases will result in an optimum particle size. Specific surface area = 4 π R2/ (ρ 4/3 π R3) = 6 / (ρ D) Light Absorption = function of D3
    13. 13. Effect of TiO2 particle size – Progress  Ishihara ST-01 TiO2 has a primary particle size of ~10 nm. This TiO2 was calcined at elevated temperatures to form TiO2 particles of various particle sizes. As received ~10 nm 400 C ~20 nm 700 C ~50 nm
    14. 14. Effect of TiO2 particle size – Previous Work  There appears to be an optimum particle size of approximately 25 nm for the degradation of organics in water.  Is there also an optimum particle size in gas-phase photocatalysis? Degussa P25 Aldrich Anatase Ishihara ST-01 DMMP Results Almquist, unpublished data Ishihara ST-01, calcined At various temperatures Phenol Results Almquist and Biswas (2002)
    15. 15. Future Work Complete effect of TiO2 primary particle size in gas-phase photocatalytic oxidation of cyclohexane.  Prepare manuscript 
    16. 16. Acknowledgements This work could not have been completed without the help from Dr. Almquist, contributing her time and effort towards this project throughout the summer and this semester Also, a special thanks to Deepika Mahendran for her help and company while working this summer
    17. 17. References [1] P. A. Deveau, F. Arsac, P. X. Thivel, C. Ferronato, F. Delpech, J. M. Chovelon, P. Kaluzny, C. Monnet, Journal of Hazardous Materials 144 (2007) 692-697 [2] G. Lu, H. Gao, J. Suo, S. Li, J. Chem. Soc., Chem. Commun. (1994) 2423. [3] C. B. Almquist, P. Biswas, Applied Catalysis A: General 214 (2001) 259-271. [4] P. Du, J. Moulijn, G. Mul. Journal of Catalysis 238 (2006) 342352. [5] U. I. Gaya, A. H. Abdullah, Journal of Photochemistry and Photobiology C: Photochemistry Reviews 9 (2008) 1-12. [6] P. Boarini, V. Carassiti, A. Maldotti, R. Amadelli, Langmuir 14 (1998) 2080. [7] E. Sahle-Demessie, M. Gonzalez, Z. M. Wang, P. Biswas, Industrial & Engineering Chemistry Research (1999), 38, 3276-