Effect of Surface Oxygen Groups on Irreversible Adsorption of Volatile Organic Compounds on Beaded Activated Carbon

• Author / Creator

  Mosavari Nezamabad, Nastaran

• Adsorption by activated carbons is a widely used method for controlling emission of volatile organic compounds (VOCs). However, accumulation of adsorbates and/or regeneration by-products (heel buildup) during cyclic process is a common challenge in this process. Irreversible adsorption restricts complete regeneration of adsorbent and reduces its capacity and lifetime. The objective of this research is to understand the impact of surface oxygen groups on heel build-up and adsorption capacity of activated carbon. For this purpose, the content of surface oxygen groups on beaded activated carbon (BAC) was modified by acid treatment and high temperature hydrogen treatment. The BET analysis showed that acid treatment and hydrogen treatment did not have a significant effect on pore size distribution and surface area. However, acid treatment increased the surface oxygen groups and hydrogen treatment decreased the surface oxygen groups’ content of BAC. Then, five-cycle adsorption/regeneration tests with eight compounds with different functional groups were completed on prepared adsorbents. Based on mass balance and thermos-gravimetric analysis, heel build-up for hydrogen treated BAC (BAC-H-950) was similar to heat treated BAC (BAC-400), but lower than that of acid-treated BAC (BAC-O-400). For oxygen deficient samples, it can be concluded that adsorption was due to physisorption as most of adsorbates were desorbed during regeneration. For oxygen-rich samples, surface oxygen groups were consumed through reaction with adsorbates. Moreover, adsorbates with benzene ring formed stronger interaction with surface oxygen groups and showed higher heel relative to other tested adsorabtes. The results of this work will provide a better understanding of irreversible adsorption and its relation to surface chemistry of adsorbents.

• Subjects / Keywords

  • Activated Carbon
  • Surface Oxygen Groups
  • Adsorption
  • Volatile Organic Compounds

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3M03Z893

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.