Nanostructured adsorbents activated carbon

Carbon-based adsorbents such as activated carbons, carbon nanotubes, and carbon nanofibres have been the subject of intensive research over the past 15 years. The research on hydrogen storage in carbon materials was dominated by announcements of extraordinary high storage capacities in carbon nanostructures. 

However, there is uncertainty about this method because of networking effects of some adsorbents including activated carbons and carbon nanostructures. Other experimental techniques that usually implement for characterizing the pore stmcture of porous materials are mercury porosim-etry. X-ray diffiaction (XRD) or small angle X-iay scattering (SAXS), and immersion calorimetry. 

Comparatively to nanotubes, nanofibers present a nanostructure made of grapheme layer stacking which is favorable to activation. Two activation systems can be used for activated carbon nanofibers physical activation by CO2 or heat, and chemical activation by KOH or RbOH [134,135]. A range of potential adsorbents was thus prepared by varying the temperature and time of activation. The structure of the CNF proved more suitable to activation by KOH than by CO, with the former yielding higher surface area carbons (up to 1000 m g ). 

Formaldehyde is one of the main pollutants in the atmosphere. In indoor air, formaldehyde mainly comes from decorating materials, paint, furniture glue, and chemical fiber carpets, and the concentration of formaldehyde is always relative low (<20 ppm). Even if the concentration of the formaldehyde is low, it can cause symptoms such as headache, nausea, coryza, pharyngitis, emphysema, lung cancer, and even death, so it is necessary to take effective measures for its removal. Adsorption by carbonaceous adsorbents is the most widely used method to purify the polluted air. Carbon nanostructure such a carbon nanofiber and fiber especially in activated form can be good adsorbents for formaldehyde [65]... 

An approach focused on fabrication of nanostructured three-dimensional electrodes and introduction of surface modifications for tethering/retention in an optimal orientation of the MCOs to permit DET to the Tl site from the electrode shows great promise for the production of biocathode prototypes for application to EFCs. A systematic study of such electrodes modified with each of the MCOs available, reporting on their activity for ORR, using DET, under defined conditions of pH, mass transport, and temperature is not yet available, and would be a valuable contribution to advance the technological application of EFCs. A welcome recent focus is normalization of ORR, based on DET to Trametes versico/or adsorbed on porous carbon-based electrode materials, to electrode volume and to electrode... 

To enhance the properties of carbon nanostructures, several strategies have been developed. For example, carbon surfaces are functionalized, modified, and customized to selectively detect molecules, chemicals, and biological compounds in liquid or gas phases. Noncovalent attachment can be utilized to preserve the structure of CNTs by adsorbing the material onto their surface. However, covalent attachment needs the surface of CNTs to have defect sites, often requiring the surface to be chemically activated to bind molecules to their surface. Alternatively, CNTs can be embedded or filled with material, as we will discuss later in this section. 

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