Adsorption of gases on 4A synthetic zeolite

1969 ◽  
Vol 47 (24) ◽  
pp. 4661-4670 ◽  
Author(s):  
R. J. Harper ◽  
G. R. Stifel ◽  
R. B. Anderson
Keyword(s):  
Characteristic Curve ◽  
Relative Strength ◽  
Principal Factor ◽  
Synthetic Zeolite ◽  
Freundlich Equation ◽  
Strong Adsorption ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Adsorption Of Gases ◽  
Permanent Gases

Equilibrium data are presented for the adsorption of permanent gases and C1 and C2 hydrocarbons on Linde 4A synthetic zeolite from 50 °C down to the boiling point of the adsorbate or to a temperature at which the rate was very slow. The Freundlich equation often fits isotherms accurately; however, these linear logarithmic plots seem to be only portions of a more general non-linear relationship. Generalized Polanyi plots did not yield a unique characteristic curve for individual adsorbates at different temperatures nor for groups of adsorbates; nevertheless, these plots are useful in estimating the relative strength of adsorption of gases. Ar, O2, CH4, and C2H6 were the least strongly adsorbed, followed in order of increasing strength by N2, CO, CO2, and C2H2. Ethylene was strongly but anomalously adsorbed. For the gases studied, the quadrupole moment seems to be the principal factor determining strong adsorption.

scholarly journals A Novel Index (RI) to Evaluate the Relative Stability of Soils Using Ultrasonic Agitation

2021 ◽  
Vol 13 (8) ◽  
pp. 4229
Author(s):  
Fakher Abbas ◽  
Fang Lin ◽  
Zhaolong Zhu ◽  
Shaoshan An
Keyword(s):  
Relative Stability ◽  
Characteristic Curve ◽  
Geometric Mean ◽  
Relative Strength ◽  
Soil Stability ◽  
Dispersion Energy ◽  
Ultrasonic Agitation ◽  
Mean Weight Diameter ◽  
Change In Mean ◽  
Wet Sieving

As soil stability is a complex phenomenon, various methods and indexes were introduced to assess the strength of soils. Because of the limitations of different stability methods and indexes (including wet sieving-based), we aimed to presents a relative stability index (RI) that was based on the estimated components of the soil overall disruptive characteristic curve (SODC): (1) soil disruption constant (Ki, that is based upon dispersion energy of soils); (2) resulting change in mean weight diameter (ΔMWD). To evaluate the effectiveness and limitations of RI as well as to compare it with classical soil stability indexes of mean weight diameter (MWD) and geometric mean diameter (GMD). Ultrasonic agitation (UA) along with a wet sieving method (followed by dry sieving) was applied against four different soils named on the basis of sample location, Qingling soil (QL), Guanzhong soil (GZ), Ansai soil (AS), and Jingbian soil (JB). To evaluate the relative strength of soils at different applied energies (increase in sonication duration usually resulted in increased input energy and temperature of soil–water suspension), soils were subjected to six sonication durations (0, 30, 60, 120, 210, and 300 s) with a fixed (and exact) initial amplitude and temperature. Output energy was calculated based on the amplitude and temperature of the suspension, vessel, and system. The most abrupt and maximum disruption of soil aggregates was observed at a dispersion energy level of 0–200 J g−1. The MWD value of surface and subsurface ranged between 0.58 to 0.15 mm and 0.37 to 0.17 mm, respectively, while GMD was ranged from 0.14 to 0.33 mm overall. The results for MWD and GMD showed a similar trend. MWD and GMD showed more strong associations with physicochemical characteristics of soil than RI. A non-significant correlation was found between RI and MWD/GMD. Contrary to MWD and GMD, RI was significantly positively correlated with sand content; this finding indicated the influential role of sand in assessing the soil’s relative strength. The results indicated that JB soil possessed the least MWD and GMD but proved to be relatively stable because of having the highest RI value.

Liquid–liquid equilibrium data for the systems {LTTM+benzene+hexane} and {LTTM+ethyl acetate+hexane} at different temperatures and atmospheric pressure

2013 ◽  
Vol 360 ◽  
pp. 54-62 ◽  
Author(s):  
Agustin S.B. Gonzalez ◽  
María Francisco ◽  
Guillermo Jimeno ◽  
Sara Lago García de Dios ◽  
Maaike C. Kroon
Keyword(s):  
Ethyl Acetate ◽  
Atmospheric Pressure ◽  
Liquid Equilibrium ◽  
Equilibrium Data ◽  
Different Temperatures

Preparation of Al2O3 Whiskers from AACH Using Hydrothermal Method and its Use for the Removal of Lead Ions by Adsorption

2021 ◽  
Vol 875 ◽  
pp. 177-183
Author(s):  
Asma Ameer ◽  
Syed Mujtaba Ul Hassan ◽  
Syed M. Husnain ◽  
Jamil Ahmad ◽  
Faisal Shahzad ◽  
...  
Keyword(s):  
High Surface ◽  
High Surface Area ◽  
Heavy Ion ◽  
Lead Ions ◽  
Hydrothermal Route ◽  
Adsorption Parameters ◽  
Ion Removal ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Adsorption Equilibrium Data

This work explores the potential of adsorption of Pb2+ by hydrothermally synthesized alumina. In comparison to other heavy ion removal techniques, adsorption is preferred in the current study as it has the edge of ease of operation and environment friendly characteristics. Synthesis of high surface area alumina whiskers was achieved by hydrothermal route which were subsequently employed for the active adsorption of lead ions. AACH (Ammonium Aluminum Carbonate Hydroxide), used as precursor for alumina, was calcined at three different temperatures i.e. 700, 900 and 1100 °C to form alumina whiskers. These whiskers were characterized by XRD, SEM, BET and FTIR. Various adsorption parameters such as contact time, pH, initial metal concentration were studied for lead ions. Maximal removal efficiency was obtained for the specimen having pH 4 and calcined at 700 °C for 60 minutes. Kinetic data was best described by pseudo second order model, whereas the adsorption equilibrium data obeyed the Langmuir adsorption isotherm model.

scholarly journals Modified Dual-Site Langmuir Adsorption Equilibrium Models from A GCMC Molecular Simulation

2020 ◽  
Vol 10 (4) ◽  
pp. 1311
Author(s):  
Junchao Wang ◽  
Yongjie Wei ◽  
Zhengfei Ma
Keyword(s):  
Molecular Simulation ◽  
Adsorption Energy ◽  
Pressure Swing Adsorption ◽  
Adsorption Equilibrium ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Adsorption Energies ◽  
Pressure Swing ◽  
Adsorption Equilibrium Data ◽  
Dual Site

In the modern industrial separation process, the pressure swing adsorption technology is widely used to separate and purify gases due to its low energy consumption, low cost, convenience, reliability, and environmental benignity. The basic elements of the design and application of the pressure swing adsorption process are adsorption isotherms at different temperatures for adsorbents. The dual-site Langmuir (DSL) adsorption equilibrium model is the mostly used model; however, this model is based on the assumption that the adsorption energy on the surface of an adsorbent is uniform and remains unchanged. Here, a grand canonical Monte Carlo (GCMC) molecular simulation was used to calculate the CO2 adsorption equilibrium on MIL-101 (Cr) at 298 K. MIL-101 (Cr) was chosen, as it has more a general pore structure with three different pores. The calculation results showed that the adsorption energies with different adsorption pressures fitted a normal distribution and the relationship of the average adsorption energies, E with pressures had a linear form described as: E = aP + c. With this relationship, the parameter b = k·exp(E/RT) in the DSL model was modified to b = k·exp((aP + c)/RT), and the modified DSL model (M-DSL) was used to correlate the adsorption equilibrium data on CO2-MIL-101 (Cr), C2H4-HHPAC, CH4-BPL, and CO2-H-Mordenite, showing better correlations than those of the DSL model. We also extended the parameter qm in the M-DSL model with the equation qm = k1 + k2T to adsorption equilibrium data for different temperatures. The obtained model (M-TDSL) was checked with the abovementioned adsorption equilibrium systems. The fitting results also indicated that the M-TDSL model could be used to improve the correlation of adsorption equilibrium data for different temperatures. The linear relationship between the average adsorption energy and adsorption pressure could be further tested in other adsorption equilibrium models to determine its universality.

MICROWAVE ASSISTED K2CO3 PALM SHELL ACTIVATED CARBON AS SORBENT FOR CO2 ADSORPTION APPLICATION

2016 ◽  
Vol 78 (8-3) ◽  
Author(s):  
Usman Dadum Hamza ◽  
Noor Shawal Nasri ◽  
Nor Aishah Saidina Amin ◽  
Jibril Mohammed ◽  
Husna Mohd Zain
Keyword(s):  
Activated Carbon ◽  
Porous Carbon ◽  
Co2 Adsorption ◽  
Co2 Uptake ◽  
Adsorption Method ◽  
Equilibrium Data ◽  
Different Temperatures ◽  
Co2 Adsorption Capacity ◽  
Adsorption Equilibrium Data ◽  
Best Fit

Carbon dioxide is believed to be a major greenhouse gas (GHG) that contributes to global warming. In this study, palm shells were used as a precursor to prepare CO2 activated carbon sorbents via carbonization, chemical impregnation with K2CO3 and microwave activation.  Adsorption equilibrium data for CO2 adsorption on the porous carbon were obtained at different temperatures using static volumetric adsorption method. Langmuir, Freundlich, Sips and Toths models were used to correlate the experimental data. The CO2 adsorption capacity at 303.15, 343.15, 378.15 443.15 K and 1 bar on the sorbent was 2.71, 1.5, 0.77, 0.69 mmol/g respectively. Sips isotherm was found to have the best fit. The results indicated that the porous carbon sorbent prepared by carbonization and microwave K2CO3 assisted activation have good CO2 uptake. The porous carbons produced are therefore good candidates for CO2 adsorption applications

Heterogeneity Analysis of Single-Walled Carbon Nanotubes from the Adsorption Equilibria of Nitrogen and Benzene

2006 ◽  
Vol 6 (11) ◽  
pp. 3583-3588
Author(s):  
Wang-Geun Shim ◽  
Hyun-Chul Kang ◽  
Chan Kim ◽  
Jae-Wook Lee ◽  
Sang-Chai Kim ◽  
...  
Keyword(s):  
Second Virial Coefficient ◽  
Nitrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Isotherm Models ◽  
Type I ◽  
Isosteric Heat Of Adsorption ◽  
Adsorption Equilibria ◽  
Equilibrium Data ◽  
Different Temperatures

Nitrogen adsorption/desorption isotherms and gravimetric methods were employed to examine the structural and adsorption properties of selected adsorbent. The equilibrium data of benzene were also obtained at three different temperatures (303.15, 313.15, and 323.15 K) with pressures up to 7 kPa. The results of nitrogen and benzene sorption isotherm revealed that SWCNTs exhibit type II with the features of type I. The Toth and UNILAN models were found to provide a reasonable correlation between the adsorption isotherm data. In addition, the adsorption second virial coefficient and the isosteric heat of adsorption were determined by using these isotherm models. The isosteric heat of adsorption and adsorption energy distribution indicated that SWCNTs have energetically and structurally heterogeneous surfaces.

scholarly journals Comparison Between Static and Dynamic Analyses of The Solid Fat Content of Coconut Oil

2018 ◽  
Vol 46 (2) ◽  
pp. 33-36
Author(s):  
Vinod Dhaygude ◽  
Anita Soós ◽  
Ildikó Zeke ◽  
László Somogyi
Keyword(s):  
Characteristic Curve ◽  
Thermal Characteristics ◽  
Solid Fat Content ◽  
Coconut Oil ◽  
Fat Content ◽  
Heat Of Fusion ◽  
Scanning Calorimetry ◽  
Solid Fat ◽  
Different Temperatures ◽  
Duration Of Heating

Abstract The objective of this work was to compare the physical and thermal characteristics of two coconut oils and their blends which were observed by the results of differential scanning calorimetry (DSC) and pulsed nuclear magnetic resonance (pNMR). Fat blends composed of different ratios (fully hydrogenated coconut oil / non-hydrogenated coconut oil: 25/75, 50/50 and 75/25) were prepared and examined for solid fat content. The solid fat content of samples was determined as a function of temperature by pNMR. The DSC technique determines the solid fat index by measuring the heat of fusion successively at different temperatures. DSC calculates the actual content of solids in fat samples and how it changes throughout the duration of heating or cooling. A characteristic curve is constructed by the correlation of enthalpies. Based on our results, it is clear that both DSC and pNMR techniques provide very practical and useful information on the solid fat content of fats. DSC is dynamic and pNMR is static. A difference in the values of the solid fat indexes of samples was observed which may be due to a fundamental difference between the two techniques. These data can be used by food manufacturers to optimize processing conditions for modified coconut oil and food products fortified with coconut oil.

Sign in / Sign up

Export Citation Format

Share Document