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.

Adsorption of As (III) on Iron Coated Quartz Sand: Influence of Temperature on the Equilibrium Isotherm, Thermodynamics and Isosteric Heat of Adsorption Analysis

2016 ◽  
Vol 14 (1) ◽  
pp. 289-298 ◽  
Author(s):  
Shashi Bala Gautam ◽  
Siraj Alam ◽  
Suantak Kamsonlian
Keyword(s):  
Quartz Sand ◽  
Freundlich Isotherm ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Isotherm Models ◽  
Influence Of Temperature ◽  
Isosteric Heat Of Adsorption ◽  
Different Temperatures ◽  
Influence Of Temperature On ◽  
Higher Temperature

AbstractThe influence of temperature on the sorption of As(III) onto iron oxide coated quartz sand (IOCQS) was studied in the temperature range of 298–318 K. An increase in temperature was found to have positive influence on the adsorption of As(III) ions onto IOCQS surfaces because of increased diffusion of As(III) ions into the pores of IOCQS at higher temperature. The enhanced sorption at higher temperature indicated endothermic adsorption process. Equilibrium isotherms for the adsorption of As(III) on IOCQS were analyzed at different temperatures. Among the conventional isotherms, Freundlich isotherm best predicted specific uptake at different temperatures, followed by Redlich–Peterson, Langmuir and Temkin isotherm models. Various thermodynamic parameters namely heat of adsorption (∆H0), change in entropy (∆S0), and Gibbs free energy change (∆G0) were computed from the equilibrium constant (KD) values. The results indicated positive value for heat of adsorption ∆H0, a positive ∆S0 and a negative ∆G0. Finally, the isosteric heat of adsorption (ΔHst,a) values were calculated and quantitatively correlated with the fractional loading of As(III) onto IOCQS. The surface heterogeneity of adsorbents could be quantitatively described with an isosteric enthalpy function of fractional loading based on Do and Do model. The results show that the IOCQS possesses heterogeneous surface with sorption sites having different activities.

scholarly journals Experimental studies on equilibrium adsorption isosteres and determination of the thermodynamic quantities of polar media on alumina Al2O3

2017 ◽  
Vol 4 (1) ◽  
pp. 34-45 ◽  
Author(s):  
Albena Yonova
Keyword(s):  
Active Sites ◽  
Adsorption Process ◽  
Surface Acidity ◽  
Experimental Studies ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Equilibrium Adsorption ◽  
Thermodynamic Quantities ◽  
Isosteric Heat Of Adsorption ◽  
Adsorption Isosteres

Abstract The present work is a revieif of theoretical and experimental study on the adsorption performance of the adsorbent Alumina (Al2O3) used in the adsorption system. An experimental investigation on the equilibrium adsorption isosteres at low pressure (< 1 atm) of working pairs Al2O3/H2O and Al2O3/C2H6O2 is carried out. The isovolume measurement method is adopted in the test setup to directly measure the saturated vapor pressures of working pairs at vapor-liquid equilibrium (dG=0 and dμi=0). Quantity adsorbed is determined from pressure, volume and temperature using gas law. The isosteric heat of adsorption is calculated from the slope of the plot of lnP versus 1/T different amounts of adsorbate onto adsorbent as follows: 0,01 vol% Al2O3/H2O; 0,03 vol% Al2O3/H2O; 0,1 vol% Al2O3/H2O; 0,01 vol% Al2O3/C2H6O2; 0,03 vol% Al2O3/C2H6O2; 0,1 vol% Al2O3/C2H6O2. This study shows that adsorption working pair Al2O3 C2H6O2 has better adsorption performances than those of the A2O3/H2O. Surface acidity! is a most important property! far both adsorption and catalysis and therefore is examined structure of active sites of alumina surface. Thermodynamic parameters such as isosteric heat of adsorption, isosteric enthalpy and entropy of adsorption are critical design variables in estimating the performance and predicting the mechanism of an adsorption process and are also one of the basic requirements for the characterization and optimization of an adsorption process

Intriguing differences in hydrogen adsorption in CPO-27 materials induced by metal substitution

2015 ◽  
Vol 3 (9) ◽  
pp. 4827-4839 ◽  
Author(s):  
Mali H. Rosnes ◽  
Martin Opitz ◽  
Matthias Frontzek ◽  
Wiebke Lohstroh ◽  
Jan Peter Embs ◽  
...  
Keyword(s):  
Comparative Study ◽  
Gas Adsorption ◽  
Hydrogen Adsorption ◽  
Isosteric Heat ◽  
Heat Of Adsorption ◽  
Hydrogen Gas ◽  
The Other ◽  
Metal Substitution ◽  
Isosteric Heat Of Adsorption ◽  
Open Metal Sites

We present a comparative study of hydrogen gas adsorption experiments on CPO-27–Cu and –Mn. The initial isosteric heat of adsorption in CPO-27–Cu is low for a material containing open metal sites and in contrast to the other members of the CPO-27 series, including the Mn compound.

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