Adsorption of Benzene and Toluene (BT) on Pre-treated Activated Carbon (PAC) and Cerium Oxide supported on Pre-treated Activated Carbon (CeO2/PAC) using Temperature Programmed Desorption (TPD) method

• Main Authors: Hallig, Herbert Klaus Martin C., Joson, Theresa P., Gallardo, Susan Manalastas
• Format: text
• Language: English
• Published: Animo Repository 2006
• Subjects: Adsorption; Carbon, Activated; Porous materials; Chemical engineering; Chemical processes
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/6180
• Institution: De La Salle University

The study focused on ascertaining the effects of different types of pre-treatment on both commercially and locally produced activated carbons in adsorbing benzene and toluene. It specifically determined not just the surface and pore characteristics of the samples but also characterized their adsorption of these volatile organic compounds (VOCs). The former was measured with the Brunauer-Emmet-Teller (BET) Analyzer, Scanning Electron Microscope (SEM) and Energy Dispersive X-Ray (EDX) while the latter was evaluated by the Temperature Programmed Desorption (TPD) Method. The two main types of activated carbon tested were the new and improved sample of the Industrial Technology Development Institute (ITDI) which was manufactured from local coconut shells and the commercially available Mapecon. Pre-treated samples of the commercial adsorbent ranging from acid-washed, thermally-treated and impregnated with CeO2 catalyst were obtained from a previous study while the fresh samples of the former were subjected to appropriate pre-treatment procedures. The thermally treated sample of the ITDI activated carbon showed an increase in its surface area and pore volume. The SEM analysis of both fresh and pre-treated ITDI samples showed that the thermally treated sample resulted to more pronounced pores. On the other hand, the EDX analysis showed that there was a significant drop in the amounts of elemental impurities on the surface of the thermally treated activated carbon sample. The BET analysis gave similar results as it indicated a decrease in the micropore diameter which implies that pre-treatment led to the exposure of more pores. It also quantified greater specific surface area and pore volume for the thermally treated local adsorbent. Moreover, the TPD results for both VOCs confirmed that there is indeed a considerable increase in the adsorption capacity of the new and improved ITDI activated carbon which is almost at par with the untreated commercial sample. Thermal treatment rendered the local adsorbent a capacity which is about 33% more than that of the fresh Mapecon activated carbon which when subjected to various pre-treatments also showed notable improvements in their adsorptive capacities. Among these pre-treated Mapecon samples, those which underwent both acid washing and thermal treatment gave the greatest numbers of active sites and breakthrough volumes. However, loading them with CeO2 catalysts resulted in decreased VOC adsorption capacity. By comparing the maximum desorption temperatures of the samples, the TPD results also proved that even though pre-treatment led to an increase in adsorbent capacity, it does not necessarily guarantee significant change in the strengths of adsorbing these VOCS. Through the coherent results of the study, it can be concluded that pre-treatment can notably improve both the surface property and adsorption capacity of an activated carbon thereby allowing local industries to produce samples which are competitive against commercially produced adsorbents.