Surface fractal dimensions of micropore walls of active carbons

Ozone Treatment of Coal- and Coffee Grounds-Based Active Carbons: Water Vapor Adsorption and Surface Fractal Micropores

“…Generally, the D v value greater than 3 is considered to be erroneous, and the case is seen when the molecular sieving effect takes place as a result of the adsorption of adsorbate molecules with molecular thickness greater than or equal to half the average pore width of active carbon (15). But, in the case of the coffee grounds-based active carbons, the molecular thicknesses of the adsorbates are less than half the pore widths and the D v Ͼ 3 holds true.…”

“…Here, for the analysis of micropore structures, the theory of volume filling of micropores (4) and the parallel plate models of micropore structures (15,(22)(23)(24) were adopted. Applicable here is the equation…”

“…In order to determine the fractal dimensions of coffee grounds-based active carbons as in the case with the previously reported active carbons (15), adsorption isotherms of benzene, methanol, 2-propanol, and toluene were measured gravimetrically using a quartz spring balance at 30°C, and that of nitrogen was measured by the conventional volumetric method at 77 K. The micropore volumes V o were determined from the Dubinin-Radushkevich plots (16), and the fractal dimensions for volume filling D v were calculated from the relationships between V o and the molar volume v as described by Tsunoda (15). Analytical data of C, H, N for both active carbons were measured by using the Perkin Elmer CHN-2400 analyzer.…”

Comparative Study of Active Carbons from Different Precursors

“…39 Applying the molecular probe technique gives an insight into the size distribution of the pores, i.e., a possible molecular sieve action, and the micropore wall thickness can be established. [40][41][42][43] The pore and the matrix structures, however, can be simultaneously studied by the small-angle X-ray scattering (SAXS) method. 44,45 Activated carbon scatters the traversing X-ray beam also in the small-angle regime, because the electron density shows heterogeneity in the colloidal region.…”

Physicochemical Properties of Carbon Materials: A Brief Overview

“…As mentioned in Section 1.3.4, the use of monoliths (see Chapter 11) is also of interest. As a final comment, it should be mentioned that the fractal approach [211,212] to the elucidation of carbon surface physics (including pore size distribution, surface roughness, and transport characteristics), although initially very promising [213][214][215][216][217][218][219][220][221][222][223][224][225][226][227], does not yet seem to have fulfilled the optimistic expectations. For example, Huang et al [224] combined TEM with image processing to investigate the micropore structure of two rayon-derived ACFs and concluded, rather prosaically, that the "fractal dimensions obtained were consistent with those obtained by nitrogen adsorption."…”