scholarly journals Adsorption thermodynamics and isosteric heat of adsorption of Thymol onto sodic, pillared and organic bentonite

2019 ◽  
Vol 8 (6) ◽  
pp. 494-504 ◽  
Author(s):  
Mohamed Elmiz ◽  
Kamal Essifi ◽  
Doha Berraaouan ◽  
Samira Salhi ◽  
Abdesselam Tahani
Keyword(s):  
Free Energy ◽  
Activation Parameters ◽  
Freundlich Isotherm ◽  
Isosteric Heat ◽  
Sorption Process ◽  
Heat Of Adsorption ◽  
Batch Adsorption ◽  
Isosteric Heat Of Adsorption ◽  
Adsorbed Quantity ◽  
Cetyl Pyridinium

We studied the temperature effects on thymol adsorption on sodium and modified clays from Nador, Morocco. The clay samples used for these analyses were purified and modified by sodium, Al13 and Cetyl Pyridinium chloride before they were used as an adsorbent for the adsorption of thymol from aqueous solution in batch adsorption procedure. The adsorption experiments were carried out as a function of temperature. The adsorption was found to be strongly dependent on the temperature. The Freundlich isotherm model showed an excellent fit to the equilibrium adsorption data. This equation indicates that the logarithm of KF is a linear function of temperature, and it decreases with temperature. The mean free energy (E) estimated from the Rankine (Calendar) modified model indicated that there is a significant relationship between adsorbed quantity and temperature and the primary mechanism governing the sorption process was a physisorption mechanism. The Arrhenius and Eyring equations were used to obtain the activation parameters such as activation energy (Ea), and enthalpy (ΔH°), entropy (ΔS°) and free energy (ΔG°) of activation for the adsorption system. Thermodynamic studies suggested the spontaneous and endothermic nature of adsorption of thymol green by sodium and purified bentonite. The isosteric heat of adsorption (ΔHX) was also determined from the equilibrium information using the Clausius–Clapeyron equation. ΔHX increased with increase in surface loading, indicating some lateral interactions between the adsorbed molecules.

scholarly journals Removal of phenol from aqueous solution by Mahua seed activated carbon: Kinetic, isotherm, mass transfer and isosteric heat of adsorption studies

2016 ◽  
Vol 22 (3) ◽  
pp. 263-273
Author(s):  
Yadav Singh ◽  
Mishra Kumar ◽  
Arvind Kumar
Keyword(s):  
Activated Carbon ◽  
Effective Diffusion ◽  
Chemical Properties ◽  
Isosteric Heat ◽  
Sorption Process ◽  
Heat Of Adsorption ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Homogeneous Surface ◽  
Isosteric Heat Of Adsorption

Mahua (Madhuca longifolia) seed activated carbon (MSAC) has been developed as an effective adsorbent for the removal of phenol from contaminated wastewaters. Prepared MSAC was characterized for various physico-chemical properties, Fourier transform infra- red (FTIR) and scanning electron microscopy (SEM) analysis. Laboratory batch experiments were performed to investigate the effect of MSAC dosage (w), pH, contact time (t), and initial phenol concentrations (Co) on sorption efficiency at optimal conditions. The maximum adsorption capacity of phenol was obtained at pH=6, t=5 h and MSAC dosage=1.2 g/l. The kinetics data of phenol adsorption was very well described by the pseudo-second-order kinetic model. The equilibrium adsorption data were best fitted to the Langmuir isotherm. The average effective diffusion coefficient 6.4?10-13 m2/s was calculated from the experimental data. Thermodynamic studies confirmed the sorption process to be spontaneous and exothermic. The isosteric heat of adsorption of phenol was found to increase with an increase in the surface loading indicating that MSAC have more homogeneous surface.

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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