Computer Analysis of the Effect of Activation Temperature on the Microporous Structure Development of Activated Carbon Derived from Common Polypody

Abstract

This paper presents the results of a computer analysis of the effect of activation process temperature on the development of the microporous structure of activated carbon derived from the leaves of common polypody (Polypodium vulgare) via chemical activation with phosphoric acid (H3PO4) at activation temperatures of 700, 800, and 900 °C. An unconventional approach to porous structure analysis, using the new numerical clustering-based adsorption analysis (LBET) method together with the implemented unique gas state equation, was used in this study. The LBET method is based on unique mathematical models that take into account, in addition to surface heterogeneity, the possibility of molecule clusters branching and the geometric and energy limitations of adsorbate cluster formation. It enabled us to determine a set of parameters comprehensively and reliably describing the porous structure of carbon material on the basis of the determined adsorption isotherm. Porous structure analyses using the LBET method were based on nitrogen (N2), carbon dioxide (CO2), and methane (CH4) adsorption isotherms determined for individual activated carbon. The analyses carried out showed the highest CO2 adsorption capacity for activated carbon obtained was at an activation temperature of 900 °C, a value only slightly higher than that obtained for activated carbon prepared at 700 °C, but the values of geometrical parameters determined for these activated carbons showed significant differences. The results of the analyses obtained with the LBET method were also compared with the results of iodine number analysis and the results obtained with the Brunauer–Emmett–Teller (BET), Dubinin–Radushkevich (DR), and quenched solid density functional theory (QSDFT) methods, demonstrating their complementarity.

Computer Analysis of the Effects of Time and Gas Atmosphere of the Chemical Activation on the Development of the Porous Structure of Activated Carbons Derived from Oil Palm Shell

“…Therefore, the concept of carrying out a new original series of analyses using more advanced and reliable methods of porous structure analysis, i.e., QSDFT [42][43][44][45] and the LBET [46][47][48][49][50] methods, taking into account, among other things, surface heterogeneity.…”

“…In the present research, the following parameters and indicators were determined: the specific surface area S QSDFT [m 2 g −1 ], the volume of micropores V QSDFT [cm 3 g −1 ], and the pore size distribution PSD obtained via the QSDFT method [42][43][44][45], the value of parameters of the porous structure. i.e., the volume of the first adsorbed layer V hA [cm 3 g −1 ], the dimensionless energy parameter for the first adsorbed layer Q A /RT, the dimensionless energy parameter for the higher adsorbed layers, B C , the geometrical parameter of the porous structure determining the height of the adsorbate molecule clusters α, the geometrical parameter of the porous structure determining the width of the adsorbate molecule clusters β calculated via the LBET method [46][47][48][49][50]. Additionally, via the fast numerical multivariate identification procedure of adsorption systems, the following information were determined: the value of the surface heterogeneity parameter h, the value of the dispersion of fitting errors σ e , the value of the indices of identification reliability w id and the adsorption energy distributions AED on the first adsorbed layer, obtained for all analyzed activated carbons.…”

Activated Carbon Nanoparticles as Adsorbent to Remove the Cadmium Ion from Aqueous Solution: Thermodynamic Study

“…According to the Bruner, Emmett, and Teller (BET) method [15], the specific surface area of (AC) was computed. The Dubinin-Radushkevich (DR) equation [16] was used to calculate the microspore volume. The nitrogen pore volume was obtained from the maximum relative pressure (P/Po=0.99) [17].…”

Functional Activated Biocarbons Based on Biomass Waste for CO2 Capture and Heavy Metal Sorption

“…Physical activation includes the oxidation and gasification of char at high temperatures. In the process of chemical activation, carbonization and activation are performed in one stage by thermal decomposition of raw materials impregnated with some chemicals, such as ZnCl 2 , NaOH, KOH, K 2 CO 3 , and H 3 PO 4 . − When activated, the textural characteristics of the materials may also change. It was shown that the sorption capacity of materials increases as a result of the activation process .…”