The XXI century started with high defying environmental issues. Among them, global warming due to greenhouse effect is one of the most important regarding its impact and interest shown by the scientific community. Several gases emissions (mainly carbon dioxide and methane) had been identified as contributing factors to this situation. Various technologies had been developed in order to achieve CO2 sequestration, being chemical and physical extraction the most used. Adsorption based technologies have gained ground in this matter and their use has become another important industrial option. The development of adsorbent materials with high CO2 adsorption capacity is related with this methodology and it is the center of this work. Nitrogen presence in adsorbents has been associated with increase in CO2 adsorption and, as wool is rich in nitrogen due to its proteic nature, it was chosen as a carbonaceous adsorbent precursor. Pristine fibers were submitted to air stabilization, carbonization and physical activation with CO2. Key temperatures of the process were selected by thermal analyses in different atmospheres. In order to explore the role of nitrogen in the adsorption, additional nitrogen functions were incorporated by heating the stabilized wool in nitric/sulphuric acid solutions, using acid concentration as variable. CO2 adsorption kinetics and isotherms were performed on modified and unmodified fibers and an increase on CO2 adsorption was observed for higher adsorption pressures. Kinetics data adjust to a pseudo second order model in all cases. Composition changes were verified by elemental analysis and Infrared spectroscopy. Raman and XR analysis were used to obtain additional information about physico-chemical changes occurring during the different processes.
Share this page on your timeline