BET theory

About: BET theory is a research topic. Over the lifetime, 9046 publications have been published within this topic receiving 286142 citations.

Adsorption isotherms of microporous-mesoporous solids revisited

Abstract: By application of the modified BET isotherm on adsorption data, for adsorption isotherms which are neither purely of the I or IV IUPAC type, it is possible to determine simultaneously the net micropore volume, the monolayer capacity and the BET parameterC. Specific surface obtained from the monolayer capacity represents the mesopore surface area and is not overestimated as in the case when the presence of micropores is neglected. The obtained BET parameterC can serve for choosing the appropriate master isotherm which is required for calculation of the mesopore-size distribution. The net micropore volume characterises the adsorption capacity when the adsorption mechanism is volume filling of pores.

Facile synthesis of porous carbon nitride spheres with hierarchical three-dimensional mesostructures for CO2 capture

Abstract: Porous carbon nitride (CN) spheres with partially crystalline frameworks have been successfully synthesized via a nanocasting approach by using spherical mesoporous cellular silica foams (MCFs) as a hard template, and ethylenediamine and carbon tetrachloride as precursors. The resulting spherical CN materials have uniform diameters of ca. 4 μm, hierarchical three-dimensional (3-D) mesostructures with small and large mesopores with pore diameters centered at ca. 4.0 and 43 nm, respectively, a relatively high BET surface area of ∼550 m2/g, and a pore volume of 0.90 cm3/g. High-resolution transmission electron microscope (HRTEM) images, wide-angle X-ray diffraction (XRD) patterns, and Raman spectra demonstrate that the porous CN material has a partly graphitized structure. In addition, elemental analyses, X-ray photoelectron spectra (XPS), Fourier transform infrared spectra (FT-IR), and CO2 temperature-programmed desorption (CO2-TPD) show that the material has a high nitrogen content (17.8 wt%) with nitrogen-containing groups and abundant basic sites. The hierarchical porous CN spheres have excellent CO2 capture properties with a capacity of 2.90 mmol/g at 25 °C and 0.97 mmol/g at 75 °C, superior to those of the pure carbon materials with analogous mesostructures. This can be mainly attributed to the abundant nitrogen-containing basic groups, hierarchical mesostructure, relatively high BET surface area and stable framework. Furthermore, the presence of a large number of micropores and small mesopores also enhance the CO2 capture performance, owing to the capillary condensation effect.

Iron-copper bimetallic nanoparticles embedded within ordered mesoporous carbon as effective and stable heterogeneous Fenton catalyst for the degradation of organic contaminants

Abstract: Iron-copper bimetallic nanoparticles embedded within ordered mesoporous carbon composite catalyst (CuFe-MC) was synthesized via a “one-pot” block-copolymer self-assembly strategy. The catalyst was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), etc. The results showed the catalyst was ordered 2D hexagonal mesostructure and iron-copper nanoparticles highly dispersed in the matrix of ordered mesoporous carbon. The composite was used as a heterogeneous Fenton catalyst and showed a promising application in the degradation of non-biodegradation organic contaminants. Eight organic compounds were chosen as model contaminants, such as phenol, bisphenol A (BPA), etc. Efficient total organic carbon (TOC) removal of each organic contaminant was achieved by using CuFe-MC as catalyst, which was higher than that by Fe2+ ion at the same reaction condition. BPA was selected to further investigate the high catalytic activity of CuFe-MC. CuFe-MC presented high adsorption capacity for BPA due to its high BET surface area (639 m2 g−1) and mesostructure. The results of BPA degradation showed that the catalytic activity of CuFe-MC was much higher than Fe-MC and Cu-MC. Electron spin resonance (ESR) and high performance liquid chromatography (HPLC) results indicated that the concentration of generated hydroxyl radicals (•OH) with CuFe-MC was much higher than Fe-MC and Cu-MC. The low iron leaching of CuFe-MC suggested its good stability. Moreover, it could be easily separated by using an external magnet after the reaction and remained good activity after being recycled for several times, demonstrating its promising long-term application in the treatment of wastewater.