title: The effects of microwave regeneration on adsorptive performance of functionalized carbon nanotubes.
abstract: In this study, the microwave regeneration method was applied to investigate the properties and adsorptive performance of functionalized carbon nanotubes (f-CNTs) in different cycles of regeneration/reuse. For this purpose, an organic and hazardous dye (Reactive Blue 19) was chosen as a widely used pollutant. N2 adsorption/desorption isotherms, scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize f-CNTs during the regeneration/reuse procedure. The morphology, specific surface area and pore volume of f-CNT samples were not significantly altered. However, the functional groups present on the f-CNTs' surface were gradually removed after successive cycles of regeneration/reuse. A sudden decrease of adsorption capacity (about 20%) after the first cycle of regeneration/reuse was attributed to the elimination of functional groups interacting with the dye molecules because of the molecular-level heating. Relatively high regeneration efficiencies (73.30 to 80.16%) proved that the microwave regeneration method was successful. Very high step stripping efficiencies (80.16 to 98.02%) in four cycles of regeneration/reuse demonstrated that the microwave regeneration method could be utilized in consecutive cycles. After four cycles of regeneration/reuse, the CNTs could not be considered as functionalized.
authors.affiliation: Department of Civil and Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez St., Tehran 15875-4413, Iran E-mail: Alavim@yahoo.com; alavi@aut.ac.ir.
authors.forename: Shahab
authors.initials: S
authors.lastname: Karimifard
authors.affiliation: Department of Civil and Environmental Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez St., Tehran 15875-4413, Iran E-mail: Alavim@yahoo.com; alavi@aut.ac.ir.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Alavi Moghaddam
mesh_terms: D000327:Adsorption; D000880:Anthraquinones / Q000302:isolation & purification*; D008855:Microscopy, Electron, Scanning; D008872:Microwaves; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000528:radiation effects*; D017550:Spectroscopy, Fourier Transform Infrared; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D000880:Anthraquinones; D037742:Nanotubes, Carbon; D014874:Water Pollutants, Chemical; C024758:Remazol Brilliant Blue R