Adsorption on Ligand-Tethered Nanoparticles

We use coarse-grained molecular dynamics simulations to study adsorption on ligand-tethered particles. Nanoparticles with attached flexible and stiff ligands are considered. We discuss how the excess adsorption isotherm, the thickness of the polymer corona, and its morphology depend on the number of ligands, their length, the size of the core, and the interaction parameters. We investigate the adsorption-induced structural transitions of polymer coatings. The behavior of systems involving curved and flat “brushes” is compared.

Molecular simulation of the adsorption characteristics of H2S in calcite slit-like pores

Hydrogen sulfide (H2S) in acid gas reservoirs is an important source of sulfur deposition in rock reservoirs. Studying the adsorption behavior of H2S in calcite slit-like pore is of great significance for predicting the amount of sulfur in natural gas. In this paper, the grand canonical Monte Carlo (GCMC) method is used to investigate the adsorption of H2S in calcite with slit-like pore. Moreover, the effects of different pressures, temperatures and pore sizes on the adsorption characteristics are discussed. The results showed that the adsorption of H2S goes up with the increasing of the pressure and gradually reaches a saturation level. And the adsorption of H2S decreases with the increasing of the temperature. The excess adsorption of H2S first increases and then decreases with the increasing of the pressure. The effect of the size on the excess adsorption capacity changes with the pressure. Meanwhile, the peak of the adsorbate near the surface of the adsorbent shows a nonmonotonic trend with the pressure.

Isothermal characteristics of methane adsorption and changes in the pore structure before and after methane adsorption with high-rank coal

The pore structure is an essential factor that influences the isothermal characteristics of methane adsorption of coal, and the pore structure is altered after methane adsorption. In this study, a high-rank coal sample was investigated via methane adsorption isothermal measurement, and changes in the pore structure were studied using low-pressure N2 adsorption and low-pressure CO2 adsorption before and after the methane adsorption. The excess adsorption capacity exhibits a rapid increase at low pressure, reaching a maximum when the test pressure is approximately 8 MPa. Following that, the excess adsorption capacity of the high-rank coal tends to decrease. After the methane adsorption, the pore volume and specific surface area of the micro-, meso-, and macropores increase as compared to those before the methane adsorption, especially for micropores with apertures greater than 0.8 nm and mesopores with apertures below 10 nm. This is mainly caused by high pressure in the methane adsorption, indicating a pressure effect on the pore structure after the methane adsorption. After the methane adsorption, the ratio of pores with various sizes in the high-rank coal is enhanced, but the connectivity for meso- and macropores presents a slight decrease.

Gaussian Process Prediction Model to Estimate Excess Adsorption Capacity of Supercritical CO2

Deep coal beds have been suggested as possible usable underground geological locations for carbon dioxide storage. Furthermore, injecting carbon dioxide into coal beds can improve the methane recovery. Due to importance of this issue, a novel investigation has been done on adsorption of carbon dioxide on various types of coal seam. This study has proposed four types of Gaussian Process Regression (GPR) approaches with different kernel functions to estimate excess adsorption of carbon dioxide in terms of temperature, pressure and composition of coal seams. The comparison of GPR outputs and actual excess adsorption expresses that proposed models have interesting accuracy and also the Exponential GPR approach has better performance than other ones. For this structure, R2=1, MRE=0.01542, MSE=0, RMSE=0.00019 and STD=0.00014 have been determined. Additionally, the impacts of effective parameters on excess adsorption capacity have been studied for the first time in literature. According to these results, the present work has valuable and useful tools for petroleum and chemical engineers who dealing with enhancement of recovery and environment protection.

Effect of Nd content on the energetics of H2O adsorption and defect structure in the Ce(1−x)NdxO(2−0.5x) system

The effect of Nd on the bond length distribution and excess adsorption enthalpy of H2O (relative to pure CeO2) in the Ce(1−x)NdxO(2−0.5x) system.