Background - Granular Activated Carbon (GAC) is the gold standard for volatile organic compound (VOC) sampling, but recently other carbonaceous porous materials like Single Walled Carbon Nanotubes (SWNT) and Porous Graphitized Carbon Particles (HDCP) have shown comparable adsorption and desorption attributes. Recent studies showed that SWNT efficiently absorb visible light and transform it in heat, hinting that irradiation of samples loaded with vapors through air sampling could be desorbed by light irradiation. This will significantly simplify the current analytical methods and will increase sensitivity of analysis. We propose to fabricate five different matrix substrates based on SWNT, HDCP and GAC, characterize their physical and adsorption properties and determine the temperature response when irradiated with various energies and frequencies of pulsed, intense visible light. We will use the irradiation scenario that yields the highest temperature increase, load the substrates with toluene vapors and determine the amount of desorbed toluene for each irradiation/substrate/loading combination. If successful this project could open the door for extensive research that will investigate the best parameters needed to build new air samplers based on this new photo-desorption principle.
We are proposing to fabricate passive air sampling devices having Single Wall Carbon Nanotubes or Porous Graphitized Carbon Particles as adsorbent media and use high intensity light flashes for desorption of contaminants for analysis. This type of non- chemical photo-thermal desorption would have a number of advantages over the conventional methods:1. It will not use toxic chemicals such as CS2 used in the current extraction methods, 2. It will be much less costly compared with the conventional thermo-desorption method and will use much less energy 3. It will allow the fractional release of contaminant from the adsorbent matrix (amount of contaminant released will be proportional with the number of light pulses), option nonexistent in the current analytical method practice, and 4. It will be virtually instantaneous compared with sometime time consuming current methods. Moreover, the desorption temperature can be precisely controlled by the light intensity, thus if multiple compounds were collected into the sampler they could be released sequentially for analysis within a relative short time interval.