• Korean Chemical Engineering Research
• /
• v.46 no.6
• /
• pp.1087-1094
• /
• 2008

This article presents a multi-scale simulation approach starting from the molecular level for the adsorption process development, specifically, in n-hexane adsorption on activated carbon. A grand canonical Monte-Carlo(GCMC) method is used for the prediction of adsorption isotherms of n-hexane on activated carbon at the molecular level. Geometric effects and hydrodynamic properties of the adsorption column are examined by means of the two dimensional CFD(computational fluid dynamics) simulation. The adsorption isotherms from the molecular simulation and the axial diffusivity from the CFD simulation are exploited for the process simulation where the elution curve of n-hexane is obtained. For the first moment(mean residence time) of the pulse-response with respect to temperature and flowrate, the process simulation results obtained from this three-steps multiscale simulation approach show a good agreement with experimental data within 20% of maximum difference. The multi-scale simulation approach addressed in this study will be useful to accelerate the adsorption process development, while reducing the number of experiments required.

• Korean Chemical Engineering Research
• /
• v.47 no.6
• /
• pp.747-754
• /
• 2009

In this study, adsorption isotherms of o-DCB(ortho-dichlorobenzene) on an activated carbon heated at $1000^{\circ}C$ for 24 hours were obtained by experiment and were predicted by using molecular simulation. The initial molecular structure of the activated carbon was designed on the basis of its molecular formula and functional groups ratio measured experimentally. Then, the molecular structure was optimized using the COMPASS(condensed-phase optimized molecular potentials for atomistic simulation studies) force field. The particle porosity, specific surface area, and particle density obtained from the optimized molecular structure of activated carbon were compared with those experimental data. The errors between experimental data and simulation results of the particle porosity, specific surface area, and particle density were shown as 7.6, 3.8, and 2.8%, respectively. Adsorption isotherms constants of o-DCB are calculated by the GCMC(grand canonical Monte Carlo) method in the optimized molecular structure of activated carbon. The simulation result of the adsorption isotherms showed an error of under 3%, compared to that of experimental data. Adsorption isotherms, adsorption heat and pore diffusivity of 2,3,7,8-TCDD(tetrachlorodibenzo-p-dioxin) was finally obtained in the same molecular structure of the activated carbon as used for o-DCB. Thus, adsorption characteristics of persistent organic pollutants on activated carbon, which are not easy to experimentally evaluate, are predicted by the molecular simulation.

• Analytical Science and Technology
• /
• v.18 no.4
• /
• pp.309-319
• /
• 2005

The adsorption characteristics of gaseous molecules on the carbonaceous adsorbent have been investigated at various temperature and pressure with different pore sizes using Grand Canonical Monte Carlo (GCMC) simulation method. The geometrical parameters and spectroscopic properties of adsorbates have been computed using density functional theory (DFT). At higher temperatures is the adsorption amount of adsorbates is decreased due to their vaporization. Considering the pore size effect, the adsorption characteristic depends on the adsorbate size, polarity and interaction between adsorbates, etc. At all cases employed in this study, the adsorption amount of adsorbates on the carbonaceous adsorbent is increased in the order $NH_3$ < $H_2S$ < $CH_3SH$, and this result is qualitatively in good agreement with the experimental observation.

• Korean Journal of Mineralogy and Petrology
• /
• v.36 no.4
• /
• pp.221-232
• /
• 2023

Carbon neutrality requires carbon dioxide reduction technology and alternative green energy sources. Palygorskite is a clay mineral with a ribbon structure and possess a large surface area due to the nanoscale pore size. The clay mineral has been proposed as a potential material to capture carbon dioxide (CO₂) and possibly to store eco-friendly hydrogen gas (H2). We report our preliminary results of grand canonical Monte Carlo (GCMC) simulations that investigated the adsorption isotherms and mechanisms of CO₂ and H₂ into palygorskite nanopores at room temperature. As the chemical potential of gas increased, the adsorbed amount of CO₂ or H₂ within the palygorskite nanopores increased. Compared to CO₂, injection of H₂ into palygorskite required higher energy. The mean squared displacement within palygorskite nanopores was much higher for H₂ than for CO₂, which is consistent with experiments. Our simulations found that CO₂ molecules were arranged in a row in the nanopores, while H₂ molecules showed highly disordered arrangement. This simulation method is promising for finding Earth materials suitable for CO₂ capture and H₂ storage and also expected to contribute to fundamental understanding of fluid-mineral interactions in the geological underground.

• Journal of the Korean Society of Tobacco Science
• /
• v.25 no.1
• /
• pp.59-69
• /
• 2003

The adsorption characteristics of H$_2$S, NH$_3$and $CH_3$SH on the graphite carbon have been investigated using Grand Canonical Monte Carlo(GCMC) method with universal force field (UFF) and dreiding force field. Most of the activated carbons used in vapor phase adsorption have the micropore of 6$\AA$ to 20$\AA$ and the specific surface area of ca. 1000 m$^2$/g, as the result of $N_2$ adsorption by BET method. For the more efficient comparison, the activated carbons have been manipulated with different pore sizes. The adsorption characteristics of H$_2$S, NH$_3$and $CH_3$SH have been considered at various temperatures and pressures. The adsorption amount using Dreiding force field is predicted to be lower than that using UFF. As the temperature is going to high, the adsorption amount of adsorbates is decreased due to their vaporization. Considering the pore size effect, the adsorption characteristic depends on the adsorbate size, polarity and interaction between adsorbates, etc. At all cases employed in this study, NH$_3$ is barely adsorbed and $CH_3$SH is preferentially adsorbed on the graphite carbon. Our theoretical result is qualitatively good agreement with the experimental observation. However, there are some quantitative discrepancies depending on the functional groups and pore size distribution on the real activated carbons used in experiment.