scholarly journals Mechanism and Characteristics of CH4/CO2/H2O Adsorption in Lignite Molecules

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhihui Wen ◽  
Yunpeng Yang ◽  
Qi Wang ◽  
Banghua Yao
Keyword(s):  
Adsorption Energy ◽  
Coalbed Methane ◽  
Physical Adsorption ◽  
Distribution Patterns ◽  
Molecular Configuration ◽  
Hydrogen Bond Energy ◽  
Isothermal Adsorption ◽  
Adsorption Characteristics ◽  
Sequestration Of Co2 ◽  
Gas Molecules

Adsorption characteristics of coalbed methane (CBM) are significant to investigate the absorption of coal, shale, and porous media. In particular, adsorption characteristics of CH4, CO2, and H2O play an important role in predicting CBM output and geologic sequestration potentials of CO2 in research fields of CO2-enhanced CBM recovery (CO2-ECBM) and sequestration of CO2. In this work, adsorption characteristics of CH4, CO2, and H2O in lignite molecules were simulated through the grand canonical Monte Carlo (GCMC) method and molecular dynamics (MD) method. Research results demonstrated that given the same temperature and pressure, the ultimate adsorption capacity of lignite per unit to H2O is the highest, followed by those of CO2 and CH4 successively. All isothermal adsorption curves conform to the “I-type” characteristics. In the saturated molecular configuration, gas molecules show different distribution patterns at two sides of the lignite molecule chain. Lignite has typical physical adsorption to CH4 and CO2, with adsorption energy provided by nonbonding energy. However, lignite has both physical adsorption and chemical adsorption to H2O, with adsorption energy provided by both nonbonding energy and hydrogen bond energy. High temperature is against adsorption of CH4, CO2, and H2O. Temperature might inhibit adsorption of gas molecules. Research conclusions lay foundations for the exploitation and development of CBM and relevant studies on sequestration of CO2.

scholarly journals Highly Selective Adsorption on SiSe Monolayer and Effect of Strain Engineering: A DFT Study

Sensors ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 977 ◽  
Author(s):  
Quan Zhou ◽  
Lian Liu ◽  
Qipeng Liu ◽  
Zeping Wang ◽  
Chenshan Gao ◽  
...  
Keyword(s):  
Compressive Stress ◽  
Adsorption Energy ◽  
Density Functional ◽  
Selective Adsorption ◽  
Physical Adsorption ◽  
Co Adsorption ◽  
Energy Charge ◽  
Strain Engineering ◽  
Zigzag Direction ◽  
Gas Molecules

The adsorption types of ten kinds of gas molecules (O2, NH3, SO2, CH4, NO, H2S, H2, CO, CO2, and NO2) on the surface of SiSe monolayer are analyzed by the density-functional theory (DFT) calculation based on adsorption energy, charge density difference (CDD), electron localization function (ELF), and band structure. It shows high selective adsorption on SiSe monolayer that some gas molecules like SO2, NO, and NO2 are chemically adsorbed, while the NH3 molecule is physically adsorbed, the rest of the molecules are weakly adsorbed. Moreover, stress is applied to the SiSe monolayer to improve the adsorption strength of NH3. It has a tendency of increment with the increase of compressive stress. The strongest physical adsorption energy (−0.426 eV) is obtained when 2% compressive stress is added to the substrate in zigzag direction. The simple desorption is realized by decreasing the stress. Furthermore, based on the similar adsorption energy between SO2 and NH3 molecules, the co-adsorption of these two gases are studied. The results show that SO2 will promote the detection of NH3 in the case of SO2-NH3/SiSe configuration. Therefore, SiSe monolayer is a good candidate for NH3 sensing with strain engineering.

Germanene: a new electronic gas sensing material

RSC Advances ◽  
2016 ◽  
Vol 6 (104) ◽  
pp. 102264-102271 ◽  
Author(s):  
Sanjeev K. Gupta ◽  
Deobrat Singh ◽  
Kaptansinh Rajput ◽  
Yogesh Sonvane
Keyword(s):  
Density Functional Theory ◽  
Ab Initio ◽  
Electronic Properties ◽  
Structural Stability ◽  
Density Functional ◽  
Gas Sensing ◽  
Functional Theory ◽  
Adsorption Characteristics ◽  
Sensing Material ◽  
Gas Molecules

The structural stability and electronic properties of the adsorption characteristics of several toxic gas molecules (NH3, SO2 and NO2) on a germanene monolayer were investigated using density functional theory (DFT) based on an ab initio method.

Adsorption Characteristics of Superplasticizer with Waste Plexiglas (WPS) onto Cement Particle Surface

2011 ◽  
Vol 328-330 ◽  
pp. 547-550
Author(s):  
Gang Zheng ◽  
Ru Min Wang ◽  
Gao Yang Zhao ◽  
Zhong Yu
Keyword(s):  
Physical Adsorption ◽  
Particle Surface ◽  
Radical Copolymerization ◽  
Cement Particle ◽  
Free Radical Copolymerization ◽  
Ζ Potential ◽  
Adsorption Characteristics ◽  
Adsorbed Quantity ◽  
Uv Visible ◽  
Repulsive Forces

In this study, by using UV-visible adsorption spectrophotometer, ζ-potential analyzer and X-ray photo spectroscopy, the adsorption characteristics and surface electrochemical properties of WPS were studied in comparison with traditional naphthalene sulfonated formaldehyde condensates (FDN) whose dispersion ability mainly depends on electrostatic repulsive forces. WPS was prepared through free radical copolymerization in self-Single screw reactive extruder and synthesized from waste plexiglas and vinyl monomers by way of special extrusion modification. The results show that the adsorption of WPS and FDN on cement particle surface approximately conforms to Langmuir’s adsorption isotherm. The adsorption of WPS belongs to physical adsorption and its saturated adsorbed quantity was 5.38mg/g. When the dosage of WPS was 1 wt.% of cement, the thickness of the adsorption layer on the surface of cement particles was 61.2 nm. The ζ-potential of cement particle with WPS changed from positive (15 mV) to negative (-64.74mV) with its concentration increasing from 0 to 20 g/L and decreased from -65.19 to-39.82 mV (reducing by 38.9%) with its concentration of 10 g/L within 60 h.

scholarly journals Adsorption Characteristics of New Coccine Dye on to Sludge Ash

2002 ◽  
Vol 20 (7) ◽  
pp. 669-681 ◽  
Author(s):  
Chih-Huang Weng
Keyword(s):  
Ionic Strength ◽  
Adsorption Energy ◽  
Dye Adsorption ◽  
Multilayer Adsorption ◽  
Sewage Sludge Ash ◽  
Adsorption Characteristics ◽  
Layer Adsorption ◽  
Decreasing Ph ◽  
Sludge Ash ◽  
Double Layer Thickness

The adsorption characteristics of an anionic azo dye (New Coccine) on to sewage sludge ash were studied. Results showed that the ash could remove the dye effectively from aqueous solution. The adsorption rate was fast and could be expressed by the modified Freundlich equation. It was found that pH is the most important parameter affecting the adsorption characteristics. The experimental data were correlated well to the non-linear multilayer adsorption isotherm. The ash adsorption capacities for the dye were in the range 3.25–5.70 mol/g and were affected by the pH, ionic strength and temperature. Decreasing pH, ionic strength and temperature increased the adsorption density. The effect of electrical double-layer thickness on the adsorption was discussed. Thermodynamic parameters indicated that the adsorption was an exothermic process. Values of the first-layer adsorption energy, ΔG10, ranged from −6.86 to −7.45 kcal/mol, suggesting that the adsorption could be considered as a physical process simultaneously enhanced by the electrostatic effect. The multilayer adsorption energy, ΔG20, ranged from −4.33 to −4.51 kcal/mol, suggesting that the adsorption was of the typical physical type. On the basis of the monolayer dye adsorption capacity, the specific surface area of the ash was calculated as 3.84–6.73 m2/g.

A LATTICE STATISTICS MODEL DERIVED FROM THE TWO-LAYER ADSORPTION PROBLEM

1965 ◽  
Vol 43 (6) ◽  
pp. 980-985
Author(s):  
D. D. Betts ◽  
D. L. Hunter
Keyword(s):  
Nearest Neighbor ◽  
Chemical Potential ◽  
Physical Adsorption ◽  
Square Lattice ◽  
Lateral Interaction ◽  
Lattice Statistics ◽  
Regular Lattice ◽  
Adsorption Sites ◽  
Layer Adsorption ◽  
Gas Molecules

A model is proposed for the physical adsorption of two layers of gas molecules at the sites of a regular lattice with lateral interaction between nearest-neighbor molecules. The model is more complicated than the two-dimensional Ising model. However, for a particular relation among the three energy parameters and at a particular value of the chemical potential the model simplifies considerably. For the simplified model and a square lattice of adsorption sites, high- and low-temperature series expansions for the specific heat have been obtained and the transition temperature estimated.

Study on the Removal of Pb2+, Cu2+, and Cd2+ from Wastewater Using Modified Stilbite

2016 ◽  
Vol 852 ◽  
pp. 1342-1348
Author(s):  
Xi Chen ◽  
Tian Shun Cui ◽  
Shuang Zhao ◽  
Xiao Jun Deng
Keyword(s):  
Heavy Metals ◽  
Competitive Adsorption ◽  
Adsorption Rate ◽  
Isothermal Adsorption ◽  
Adsorption Time ◽  
Adsorption Characteristics ◽  
Static Conditions ◽  
The Impact

In this study, we studied the ability of modified Stilbite to adsorb heavy metals Pb2+, Cu2+, and Cd2+ from wastewater. In static conditions, we investigated the impact of pH, temperature, dosage, and the competitive adsorption characteristics of the modified Stilbite in addressing pollution of wastewater with Pb2+, Cu2+, Cd2+. The testing showed that: under normal circumstances, with a pH between 5-6, a dosage of 0.7 g, and an adsorption time of 90 minutes, the adsorption rate of the three metals was above 90%. The adsorption rate of Cu was greater than Pb, which was greater than Cd. The modified Stilbite adsorption of the three metals met Langmuir and Freundlich isothermal adsorption equations. The study also revealed that regenerated Stilbite, after adsorption, can still continue to be used for adsorption of heavy metals.

scholarly journals Design of Complex Solid‐Solution Electrocatalysts by Correlating Configuration, Adsorption Energy Distribution Patterns, and Activity Curves

2020 ◽  
Vol 59 (14) ◽  
pp. 5844-5850 ◽  
Author(s):  
Tobias Löffler ◽  
Alan Savan ◽  
Hajo Meyer ◽  
Michael Meischein ◽  
Valerie Strotkötter ◽  
...  
Keyword(s):  
Solid Solution ◽  
Energy Distribution ◽  
Adsorption Energy ◽  
Distribution Patterns ◽  
Adsorption Energy Distribution

Isothermal Adsorption Characteristics and Kinetics of Cr Ions onto Ettringite

2019 ◽  
Vol 34 (3) ◽  
pp. 587-595 ◽  
Author(s):  
Xin Wang ◽  
Suping Cui ◽  
Bilan Yan ◽  
Lan Wang ◽  
Yanhe Chen ◽  
...  
Keyword(s):  
Isothermal Adsorption ◽  
Adsorption Characteristics ◽  
Kinetics Of

scholarly journals Effects of Pore Structures of Different Maceral Compositions on Methane Adsorption and Diffusion in Anthracite

2019 ◽  
Vol 9 (23) ◽  
pp. 5130 ◽  
Author(s):  
Jincheng Zhao ◽  
Yong Qin ◽  
Jian Shen ◽  
Binyang Zhou ◽  
Chao Li ◽  
...  
Keyword(s):  
Coalbed Methane ◽  
Pore Diameter ◽  
Fractal Theory ◽  
Effective Diffusion ◽  
Low Pressure ◽  
Methane Adsorption ◽  
Isothermal Adsorption ◽  
Diffusion Capacity ◽  
Pore Structures ◽  
Study Results

The pore structure of coal reservoirs is the main factor influencing the adsorption–diffusion rates of coalbed methane. Mercury intrusion porosimetry (MIP), low-pressure nitrogen adsorption (LP-NA), low-pressure carbon dioxide adsorption (LP-CA), and isothermal adsorption experiments with different macerals were performed to characterize the comprehensive pore distribution and methane adsorption–diffusion of coal. On the basis of the fractal theory, the pore structures determined through MIP and LP-NA can be combined at a pore diameter of 100 nm to achieve a comprehensive pore structural splicing of MIP, LP-NA, and LP-CA. Macro–mesopores and micro-transitional pores had average fractal dimensions of 2.48 and 2.18, respectively. The Langmuir volume (VL) and effective diffusion coefficients (De) varied from 31.55 to 38.63 cm3/g and from 1.42 to 2.88 × 10−5 s−1, respectively. The study results showed that for super-micropores, a higher vitrinite content led to a larger specific surface area (SSA) and stronger adsorption capacity but also to a weaker diffusion capacity. The larger the average pore diameter (APD) of micro-transitional pores, the stronger the diffusion capacity. The diffusion capacity may be controlled by the APD of micro-transitional pores.

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