(371g) Adsorbents for Selective Adsorption of VOC Biomarkers from Simulated Breath

The detection and quantification of volatile organic compounds (VOCs) biomarkers from exhaled human breath is fast becoming an acceptable technique for easy and rapid testing for several illnesses. To identify and quantify these VOC biomarkers, selective sorbent materials are of major importance. Sorbents with the desired selectivity could lead to the development of inexpensive, energy efficient and quick diagnosis of diseases using adsorption and desorption mechanism to detect and quantify these VOCs. In this work, several adsorbent materials, including activated carbon, zeolites, and metal organic frameworks (MOFs), have been tested for their VOC capacities to acquire an in-depth understanding of VOC adsorption mechanisms on these materials. The influence of VOC characteristics and properties such as polarity, boiling point, molecular diameter, etc., on their interactions with adsorbents was studied. It was observed that the adsorption loadings increased with increase in pore volume and total surface area, implying that pore filling is the prevalent adsorption mechanism. Nitrogen sites were introduced to adsorbents via amine impregnation of carbon samples and synthesis of MOFs using functionalized ligands. Adsorption loadings in functionalized adsorbents were lower than unfunctionalized adsorbents. Moreover, functionalized MIL-101 exhibited slower adsorption dynamics than the unfunctionalized MOF. CO₂ and water vapor breakthrough adsorption experiments were also carried out on the functionalized and unfunctionalized materials. Results showed both water and CO₂ breakthrough times on carbon samples with nitrogen sites increased significantly in humid streams. Therefore, this may be applied to selectively adsorb two major components of human exhaled breath prior to reaching the sorbent bed for VOC separation in a layered bed system.