scholarly journals Roles of adsorption potential and surface free energy on pure CH4 and CO2 adsorption under different temperatures

2019 ◽  
Vol 23 (Suppl. 3) ◽  
pp. 747-755
Author(s):  
Tong-Qiang Xia ◽  
Jing-Yu Meng ◽  
You-Pai Wang ◽  
Jian-Hong Kang ◽  
Hong-Yun Ren
Keyword(s):  
Free Energy ◽  
Adsorption Capacity ◽  
Surface Free Energy ◽  
Gas Adsorption ◽  
Reduction Rate ◽  
Adsorption Potential ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Static Volumetric Method ◽  
C 50

To fill the knowledge of adsorption characteristics of CH4 and CO2 associated with equilibrium and thermodynamics, adsorption equilibrium tests of pure gas on a coal were conducted under the different temperatures (35 ?C, 50 ?C, and 65?C by the static volumetric method. The equilibrium data were well matched by the SLD-PR model. The influence of some significant factors including temperature, pressure, adsorption potential and surface free energy on gas adsorption capacity were discussed. The results showed that the higher temperature (gas pressure) corresponds to the smaller (larger) adsorption capacity and the larger adsorption potential is, the smaller adsorption capacity is. Taking CH4 as adsorbent, the modified Langmuir equation can well match the SLD-PR model. However, when the adsorption medium is CO2, modified Freundlich equation is better. Using the two modified equations, we study further the relationship among the variation of surface free energy, its reduction rate and gas adsorption capacity. It can be concluded the larger the gas adsorption capacity is, the greater the reduction of surface free energy is, and the smaller the reduction rate of surface free energy is.

scholarly journals Roles of adsorption potential and surface free energy on pure CH4 and CO2 adsorption under different temperatures

2019 ◽  
pp. 180-180
Author(s):  
Tong-Qiang Xia ◽  
Jing-Yu Meng ◽  
You-Pai Wang ◽  
Jian-Hong Kang ◽  
Hong-Yun Ren
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Co2 Adsorption ◽  
Adsorption Potential ◽  
Different Temperatures

scholarly journals Improve in CO2 and CH4 Adsorption Capacity on Carbon Microfibers Synthesized by Electrospinning of PAN

Fibers ◽  
2019 ◽  
Vol 7 (10) ◽  
pp. 81 ◽  
Author(s):  
Reyna Ojeda-López ◽  
J. Marcos Esparza-Schulz ◽  
Isaac J. Pérez-Hermosillo ◽  
Armin Hernández-Gordillo ◽  
Armando Domínguez-Ortiz
Keyword(s):  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Gas Adsorption ◽  
Morphological Structure ◽  
Different Temperatures ◽  
Ch4 Adsorption ◽  
Stabilization Temperature ◽  
Carbon Microfibers

Carbon microfibers (CMF) has been used as an adsorbent material for CO2 and CH4 capture. The gas adsorption capacity depends on the chemical and morphological structure of CMF. The CMF physicochemical properties change according to the applied stabilization and carbonization temperatures. With the aim of studying the effect of stabilization temperature on the structural properties of the carbon microfibers and their CO2 and CH4 adsorption capacity, four different stabilization temperatures (250, 270, 280, and 300 °C) were explored, maintaining a constant carbonization temperature (900 °C). In materials stabilized at 250 and 270 °C, the cyclization was incomplete, in that, the nitrile groups (triple-bond structure, e.g., C≡N) were not converted to a double-bond structure (e.g., C=N), to form a six-membered cyclic pyridine ring, as a consequence the material stabilized at 300 °C resulting in fragile microfibers; therefore, the most appropriate stabilization temperature was 280 °C. Finally, to corroborate that the specific surface area (microporosity) is not the determining factor that influences the adsorption capacity of the materials, carbonization of polyacrylonitrile microfibers (PANMFs) at five different temperatures (600, 700, 800, 900, and 1000 °C) is carried, maintaining a constant temperature of 280 °C for the stabilization process. As a result, the CMF chemical composition directly affects the CO2 and CH4 adsorption capacity, even more directly than the specific surface area. Thus, the chemical variety can be useful to develop carbon microfibers with a high adsorption capacity and selectivity in materials with a low specific surface area. The amount adsorbed at 25 °C and 1.0 bar oscillate between 2.0 and 2.9 mmol/g adsorbent for CO2 and between 0.8 and 2.0 mmol/g adsorbent for CH4, depending on the calcination treatment applicated; these values are comparable with other material adsorbents of greenhouse gases.

scholarly journals Solvent-Free Synthesized Monolithic Ultraporous Aluminas for Highly Efficient Removal of Remazol Brilliant Blue R: Equilibrium, Kinetic, and Thermodynamic Studies

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3054
Author(s):  
Huan Xu ◽  
Guilhem Boeuf ◽  
Zixian Jia ◽  
Kairuo Zhu ◽  
Mehrdad Nikravech ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Adsorption Process ◽  
Mechanical Stability ◽  
Brilliant Blue ◽  
Isotherm Models ◽  
Order Model ◽  
Isochronous Annealing ◽  
Remazol Brilliant Blue R ◽  
Equilibrium Data ◽  
Different Temperatures

In this study, ultraporous aluminas (UPA) were synthesized as new effective adsorbents for Remazol Brilliant Blue R (RBBR) removal from aqueous solutions. The UPA monoliths were grown via facile oxidation process, followed by isochronous annealing treatment in air at different temperatures, through which γ, θ, and α phase polycrystalline fibrous grains of UPA can be accordingly obtained. The experimental factors that affect the material adsorption performances including initial pH, contact time, and temperature were comprehensively studied by batch experiments. The RBBR adsorption isotherms of UPA(γ) and UPA(θ) powders were found almost identical, while UPA(α) powders showed low effectiveness. To obtain the desirable mechanical stability of the UPA monolith with considerable RBBR adsorption capacity, UPA(θ) powders were further studied. The UPA(θ) powders exhibited maximum RBBR adsorption at pH 2 due to the positively charged surface under acidic conditions. Compared with the Lagergren pseudo-first-order model, the pseudo-second-order model was found to explain the adsorption kinetics better. Despite the film diffusion dominating the adsorption process, the contributions of the intraparticle diffusion and chemical reactions were also found significant. The adsorption equilibrium data at different temperatures were fitted by the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich (D–R) isotherm models. The Langmuir model was found the most effective in the description of equilibrium data, and the maximum RBBR adsorption capacity retained by UPA(θ) powders was 122.55 mg·g−1 at 295 K. Thermodynamic parameters (ΔG0, ΔH0, and ΔS0) indicated the adsorption process was spontaneous and exothermic in nature.

Thermodynamics of Organic Dyes Adsorption onto Thermal Modified Rectorite

2012 ◽  
Vol 463-464 ◽  
pp. 194-197
Author(s):  
Jing Yan Song ◽  
Ling Rong He
Keyword(s):  
Free Energy ◽  
Gibbs Free Energy ◽  
Organic Dyes ◽  
X Ray Diffraction ◽  
Adsorption Interaction ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Hoff Equation ◽  
Dyes Adsorption ◽  
Langmuir And Freundlich Equations

Adsorption behavior of Rhodamine B (RhB) onto thermal modified rectorite (TM-R) has been thermodynamically investigated. The thermal modified rectorite prepared at different temperatures was characterized by X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET). The analysis of the isotherm equilibrium data using the Langmuir and Freundlich equations by linear methods showed that the data fitted better with Freundlich model than the Langmuir model. Thermodynamic parameters were calculated based on Van’t Hoff equation. The average change of standard adsorption heat of RhB was 88.96 kJ/mol. The adsorption Gibbs free energy changes are in the range of -26.88～-34.52 kJ/mol, The negative of adsorption Gibbs free energy changes in all cases are indicative of the spontaneous nature of the adsorption interaction, and the values of adsorption entropy changes are positive.

scholarly journals Application of cyanated asphaltenes in gas-phase adsorption processes for removal of volatile organic compounds

2019 ◽  
Vol 74 (3) ◽  
pp. 995-1008
Author(s):  
Maksymilian Plata-Gryl ◽  
Malwina Momotko ◽  
Sławomir Makowiec ◽  
Grzegorz Boczkaj
Keyword(s):  
Free Energy ◽  
Adsorption Capacity ◽  
Surface Free Energy ◽  
Adsorption Isotherms ◽  
Retention Volume ◽  
Scale Up ◽  
Breakthrough Curves ◽  
Proton Acceptor ◽  
Acceptor Interaction ◽  
Gas Phase Adsorption

Abstract The paper presents an innovative, chemically modified (methylcyanated) asphaltene-based adsorbent that can be an interesting low-cost alternative for traditional adsorbents. Adsorption properties of adsorbents were examined by inverse gas chromatography technique, adsorption isotherms, and breakthrough curves. A significant increase in retention volume for pyridine, 2-pentanone, nitropropane, toluene, and 1-butanol was observed. Rohrschneider–McReynolds constants revealed an increase in strength of interactions as a result of the modification, especially in strong proton–acceptor interaction (by a factor of 4.6). The surface-free energy of asphaltene adsorbents increased from 136.71 to 169.95 mJ m−2 after modification. It is similar to the surface-free energy of silica or alumina. Moreover, modified adsorbent shows very high adsorption potential for pyridine. Adsorption isotherms revealed that monolayer adsorption capacity for pyridine increased 1.5 times after modification. Breakthrough curves of pyridine indicate that chemical modification increased the adsorption capacity, removal efficiency, and throughput. Scale-up calculations revealed that adsorption column packed with modified asphaltene adsorbent would be almost two times smaller compared to a column packed with unmodified one. Graphic abstract

scholarly journals Greenhouse Crop Residue and Its Derived Biochar: Potential as Adsorbent of Cobalt from Aqueous Solutions

Water ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1282 ◽  
Author(s):  
Irene Iáñez-Rodríguez ◽  
Mónica Calero ◽  
Gabriel Blázquez ◽  
María Ángeles Martín-Lara
Keyword(s):  
Aqueous Solutions ◽  
Adsorption Capacity ◽  
Crop Residue ◽  
Pyrolysis Temperature ◽  
Low Cost ◽  
Treatment Temperature ◽  
Cobalt Removal ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
And Behavior

This work is focused on the removal of cobalt from aqueous solutions using the greenhouse crop residue and biochars resulting from its pyrolysis at different temperatures, which have not been previously used for this purpose. This study aims to provide insights into the effect of pyrolysis temperature as a key parameter on the cobalt adsorption capacity of these materials. Firstly, the main physicochemical properties of greenhouse crop residue and its biochars prepared under different pyrolysis temperatures were characterized by elemental analysis and FT-IR, among others. Then, the cobalt adsorption capacity of materials was evaluated in batch systems. The best results were obtained for the biochar prepared by pyrolysis at 450 °C (adsorption capacity of 28 mg/g). Generally, the adsorption capacity of the materials increased with pyrolysis temperature. However, when the treatment temperature was increased up to 550 °C, a biochar with worse properties and behavior than cobalt adsorbent was produced. Rather than surface area and other physical properties, functional groups were found to influence cobalt adsorption onto the prepared materials. The adsorption kinetics showed that the adsorption followed pseudo-second-order kinetics model. The obtained equilibrium data were fitted better by the Langmuir model rather than the Freundlich model. Finally, decomposition of loaded-materials was analyzed to assess their possible recycling as fuel materials. The study suggested that greenhouse crop residue can be used as a low-cost alternative adsorbent for cobalt removal from aqueous solutions.

scholarly journals Impact of tectonic deformation on coal methane adsorption capacity

2019 ◽  
Vol 37 (9-10) ◽  
pp. 698-708
Author(s):  
Wu Li ◽  
Bo Jiang ◽  
Yan-Ming Zhu
Keyword(s):  
Adsorption Capacity ◽  
Gas Adsorption ◽  
Structural Parameters ◽  
Methane Adsorption ◽  
Tectonic Deformation ◽  
Chemical Structures ◽  
C 50 ◽  
Coal Macerals ◽  
Increasing Temperature ◽  
Physical And Chemical

Tectonic deformation can cause significant changes in the physical and chemical structures of coal by damaging the macrostructure and macromolecular composition. For thorough research on the coal tectonic deformation impacts on gas adsorption capacity, this paper collected and summarized the parameters of experimental adsorption isotherms and coal macerals, conducted proximate and ultimate analyses, and systematically discussed the adsorption properties of different structures of coals and the influence of temperature and pressure on coal adsorption. Furthermore, the semi-quantitative relationships between the structural parameters of coal and its methane adsorption capacity are explored. The results show that (1) due to different tectonic stresses, the molecular and porous structures of different types of tectonic coal exhibit significant differences (e.g. sample N25, which is in a fault zone, has the highest methane adsorption capacity), and (2) coal methane adsorption capacity decreases along with increasing temperature. At a pressure of 12 MPa, primary coal (N32) showed Langmuir volume (VL) values of 15.38, 9.58, and 7.86 cm3/g and Langmuir pressure (PL) values of 3.82, 2.07, and 1.81 MPa at temperatures of 30°C, 50°C, and 70°C, respectively. (3) The Langmuir volume appears to have a linear relationship with parameters ID1/IG, Al/OX, and A-factor, as well as a parabolic curve relationship with fa, thereby illustrating that increases of apparent aromaticity can raise CH4 adsorption on coal.

scholarly journals Determination of relevance between surface free energy and adsorption capacity of cement particles

2016 ◽  
Vol 21 (3) ◽  
pp. 733-741
Author(s):  
Jihai Yu ◽  
Zhengmao Ye ◽  
Zhenzhen Xia ◽  
Bin Wu ◽  
Pengkun Hou
Keyword(s):  
Free Energy ◽  
Adsorption Capacity ◽  
Surface Free Energy
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