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

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


2011 ◽  
Vol 383-390 ◽  
pp. 3056-3062 ◽  
Author(s):  
Dong Juan Kang ◽  
Xiao Long Tang ◽  
Jin Hui Peng ◽  
Hong Hong Yi ◽  
Ping Ni ◽  
...  

The aim of this paper is to study the adsorption characteristics of nitric oxide (NO) and sulfur dioxide (SO2) on raw coal activated carbon over temperature ranged 298~343K using a static volumetric adsorption apparatus. The adsorption equilibrium data for NO and SO2were fitted to Freundlich, Dubinin-Radushkevich (D-R) and Sips adsorption isotherm model. Isosteric heat of adsorption was determined by the Clausius-Clapeyron equation. It was found that Sips adsorption isotherm model is more suitable for description of NO adsorption process at 298K, 313K and 328K and SO2adsorption process at 313K, 328K and 343K, however, D-R adsorption isotherm model is more suitable for description of the NO adsorption process at 343K and SO2adsorption process at 298K. The isosteric heat of adsorption values of SO2increase slightly as the adsorbed amounts increasing from 0.8 to 1.6mg/g, but the isosteric heat of adsorption values of NO show a converse trend. Meanwhile, NO and SO2adsorbed on coal activated carbon at the four temperatures may be a dominant of physical adsorption.



2012 ◽  
Vol 472-475 ◽  
pp. 1652-1658
Author(s):  
Qing Rong Zheng ◽  
Shuai Gao ◽  
Chen Jie

For developing carbon based adsorbents for hydrogen storage, Staram PCTPro E&E was employed and activated carbon SAC-02 having specific surface area about 2074m2/g was selected to measure isotherms of hydrogen adsorption respectively from temperature range 77.15K-110.15K and 253.15K-293.15K. Isosteres of hydrogen adsorption on the activated carbon was then plotted to determine the isosteric heat of hydrogen adsorption, and temperature dependent of Henry law constants were further applied to set the limit isosteric heat of adsorption at zero surface coverage. Results show that the isosteric heat of adsorption is about 3.6-5.4kJ/mol with a mean value 4.38kJ/mol at zero surface coverage. Results also reveal that adsorption isosteres of adsorption data at different temperature regions bring about a different isosteric heat of adsorption due to the variation in contributions from thermal motion of adsorbate molecules. Conclusions are drawn that adsorption isosteres on the adsorption data in correspondence with the lowest and highest temperatures of the hydrogen storage system should be carried out to determine the isosteric heat of adsorption for effectively managing the thermal effect.





1996 ◽  
Vol 183 (1) ◽  
pp. 131-134 ◽  
Author(s):  
A.K. Helmy ◽  
E.A. Ferreiro ◽  
S.G. de Bussetti


AIChE Journal ◽  
1987 ◽  
Vol 33 (3) ◽  
pp. 510-514 ◽  
Author(s):  
Orhan Talu ◽  
R. L. Kabel


2015 ◽  
Vol 3 (9) ◽  
pp. 4827-4839 ◽  
Author(s):  
Mali H. Rosnes ◽  
Martin Opitz ◽  
Matthias Frontzek ◽  
Wiebke Lohstroh ◽  
Jan Peter Embs ◽  
...  

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.



Langmuir ◽  
1998 ◽  
Vol 14 (21) ◽  
pp. 6323-6327 ◽  
Author(s):  
Huanhua Pan ◽  
James A. Ritter ◽  
Perla B. Balbuena


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