Industrial adsorbents pore volume distribution

In recent years, activated carbons fibers (ACFs) because of their high surface area, microporous character, and the chemical nature of their surface have been considered potential adsorbents for the removal of heavy metals from industrial wastewater [1 3]. The properties of ACFs are determined by their microstructure, it is therefore important to investigate the microstructure of ACFs in terms of specific surface area, micropore volume, pore size distributions, surface chemistry and so on. Also, the adsorption properties of carbonaceous adsorbents are dependent on not only the porous structure but also the surface chemistry [3,4]. 

The values of the mesopore volumes and radii and the value of the fiactal dimension, are convergent, as for the size order, with the corresponding values obtained during studies of the structure AI2O3 [64], Values of pore volume near 2 nm have the highest intensity in this curve. The concentration of mesopores decreases with increase of their radius. The observed shape of the pore-size distribution curve is typical for most industrial mesoporous adsorbents. For example, this shape is similar to that found from low-temperature nitrogen adsorption isotherms on various activated carbons by using the Dollimore-Heal method [63]. 

The isotherms dealing with physical adsorption of gases and vapours give most important characteristics of industrial sorbents which include, among other things, pore volume, pore size or energy distribution and surface area. Moreover, these very specific curves can be interpreted in order to obtain information about the adsorption mechanism strictly connected with interactions between adsorbent and adsorbate molecules and give the possibility to assess the efficiency of industrial adsorbents applied in separation, purification and other utilitarian processes. 

The commercial sample, spherical bead activated carbon, was supplied by Kureha Chemical Industry. This activated carbon is referred to as Kureha carbon, which has a total micropore volume of 0.56 cm g" and a BET surface area of 1300 m g . The detailed textural properties of Kureha carbon are reported elsewhere [9]. The pore size distribution was evaluated in terms of the simulation of the density hmctional theory (DFT) using the isotherm data of nitrogen adsorption at 77 K and relative pressures up to 0.2. Only micropores contribute to the total pore volume and surface area. This was further confirmed by mercury intrusion porosimetry, no significantly additional porosity was observed in the pore size range from 2 nm to 100 pm. So, the investigated adsorbent is a purely microporous material and its pore size distribution covers the range from 0.4 to 1.9 nm [9]. 

Manometric gas adsorption is the most frequently applied method to determine BET specific surface areas (BET-SSA), specific pore volumes and pore size distributions of adsorbents. The analysis of uncertainty in the measured data and their propagation to the combined standard uncertainty in BET-SSA is well established [1]. An evaluated uncertainty in BET-SSA and pore volume has important contributions to testing adsorption theory models and appropriate industrial process economics. The role of pore volume becomes important when investigating gas adsorption at high-pressures and at supercritical conditions, since this parameter is required to determine the absolute amount adsorbed compared with the surface excess amount adsorbed. 

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