Adsorption and Desorption Process

2008 ◽  
pp. 18-27
Keyword(s):  
Desorption Process ◽  
Adsorption And Desorption

scholarly journals Adsorption and Desorption Behavior of Herbicide Mefenpyr-diethyl in the Agricultural Soils of Morocco

2018 ◽  
Vol 7 (5) ◽  
pp. 386-395 ◽  
Author(s):  
Abdellah El Boukili ◽  
Nidae Loudiyi ◽  
Ahmed El Bazaoui ◽  
Abderrahim El Hourch ◽  
M'Hamed Taibi ◽  
...  
Keyword(s):  
Organic Matter ◽  
Adsorption Capacity ◽  
Agricultural Soils ◽  
Organic Matter Content ◽  
Matter Content ◽  
Isotherm Models ◽  
Desorption Process ◽  
Adsorption And Desorption ◽  
Total Percentage ◽  
Adsorption Isotherm Models

The present study was conducted in order to investigate the adsorption and desorption behavior of Mefenpyr-diethyl (MFD) using the batch equilibration technique in four soils, with different ranges of organic matter content, from different regions of Morocco orders of Benimellal (Soil 1), Settat (Soil 2), Sidi Bettach (Soil 3) and EL Hajeb (Soil 4). The adsorption isotherm models Langmuir, linear and Freundlich were used to compare the adsorption capacity of the soils. The results indicated that the Freundlich equation provided the best fit for all adsorption data. The values of KF and Kd ranged from 4.45 to 15.9 and 4.30 to 18.30 L.kg-1 , respectively. The calculated total percentage of desorption values from the Soil 1, Soil 2, Soil 3 and Soil 4 after the four desorption process were 59 %; 55,6 %; 37,5 % and 52,5%, respectively. Highest adsorption and desorption were observed in soil 1, and the lowest was in soil 3. According to the adsorption and desorption results, organic matter and clay seemed to be the most important factors influencing the adsorption capacity of MFD.

Characteristics of Dynamics Sorption Isotherms of Date Flesh Powder Rich in Fiber

2016 ◽  
Vol 12 (5) ◽  
pp. 469-480 ◽  
Author(s):  
Mohammad Fikry ◽  
Alhussein M. Al-Awaadh
Keyword(s):  
Moisture Content ◽  
Water Activity ◽  
Sorption Isotherms ◽  
Isosteric Heat ◽  
Phoenix Dactylifera ◽  
Dynamic Vapor Sorption ◽  
Desorption Process ◽  
Adsorption And Desorption ◽  
Peleg Model ◽  
Wide Range

Abstract Dynamic vapor sorption equipment (AQUADVS) was used to determine adsorption and desorption isotherms for powder rich in fiber (PRF) produced from Palm Date flesh of Sifri cultivar (Phoenix dactylifera L.) at temperatures 25, 35 and 45 °C in a wide range of water activity (0.09–0.87). Equilibrium was achieved within 29 and 25 h for the adsorption and desorption process respectively. The obtained data were fitted to ten models (Peleg, GAB, BET, Halsey, Oswin, Smith, Modified Henderson, Adam and Shove, Modified Oswin and Modified Halsey). The results indicated that the PRF followed type III behavior. The empirical Peleg model was found to be the best to represent the experimental data in the water activity range 0.09–0.87. The isosteric heat of sorption and the differential entropy decreased by increasing the moisture content and can be predicted by polynomial functions. Glass transition temperatures (Tg) of PRF were determined. The Tg decreased as the moisture content increased and can be correlated using the Gordon and Taylor model (R2=0.976). The PRF should be stored at moisture less than 9 d.b.% and temperature less than 35 °C.

EFFECT OF GRAIN SIZE AND ACTIVATION TIME OF ZEOLITE TO ADSORPTION AND DESORPTION OF NH4OH AND KCL AS MODEL OF FERTILIZER-ZEOLITE MIX

Konversi ◽  
2018 ◽  
Vol 6 (2) ◽  
pp. 21 ◽  
Author(s):  
Muhammad Prasanto Bimantio
Keyword(s):  
Grain Size ◽  
Rate Constant ◽  
Adsorption Process ◽  
Activation Time ◽  
Desorption Process ◽  
Adsorption And Desorption ◽  
Catalyst Carrier ◽  
Three Samples ◽  
Research Procedure ◽  
Desorption Rate Constant

Abstract - Zeolites can be used as adsorbent, ion exchange, catalyst, or catalyst carrier. Application of fertilizer use in the zeolite also be one of the interesting topic. Zeolites in a mixture of fertilizer can use to control the release of nutrients. The purpose of this research is to study the effect of grain size and time of the activation of zeolite to adsorption and desorption of NH4OH and KCl as modeling of ZA and KCl fertilizer, to obtain the value of adsorption rate constant (ka) and desorption rate constant (kd). This research procedure include: the process of adsorption by adding zeolite with various size and time of activation into a sealed beaker glass and let the adsorption process occurs for 24 hours. After 24 hours, the solution was filtered, the zeolite then put in 100 ml of aquadest into a sealed beaker glass and let the desorption process happened for another 24 hours. Three samples with the largest difference solution concentrations looked for the value of the ka and kd. Zeolite configuration with the largest ka is trialed with fertilizer and compared with the value of ka obtained from modeling. The result for NH4OH adsorbate, -50+60 mesh 2 hours configuration zeolite give the largest ka. For KCl adsorbate, -30+40 mesh 4 hours configuration zeolite give the largest ka. The value between modeling and trials with fertilizers are not much different. Keywords: zeolite, ZA fertilizer, KCl fertilizer, mathematical modelling.

Study of Heavy Metal Ions Mn(II), Zn(II), Fe(II), Ni(II), Cu(II), and Co(II) Adsorption Using MFe2O4 (M=Co2+, Mg2+, Zn2+, Fe2+, Mn2+, and Ni2+) Magnetic Nanoparticles as Adsorbent

2017 ◽  
Vol 901 ◽  
pp. 142-148 ◽  
Author(s):  
Wahyu Waskito Aji ◽  
Edi Suharyadi
Keyword(s):  
Heavy Metal ◽  
Metal Ions ◽  
Metal Ion ◽  
Heavy Metal Ions ◽  
Ferrite Nanoparticles ◽  
Adsorption Ability ◽  
Desorption Process ◽  
Adsorption And Desorption ◽  
Ion Removal ◽  
Heavy Metal Ions Removal

Removal of heavy metal ions (Co2+, Cu2+, Zn2+, Fe2+, Mn2+, and Ni2+) from artificial wastewater has been successfully perfomed by adsorption process using magnetic ferrite (MFe2O4; M=Co2+, Mg2+, Zn2+, Fe2+, Mn2+, and Ni2+) nanoparticles. Ferrite nanoparticles were synthesized using coprecipitation method and used as absorbent in heavy metal ions removal with concentration of 5 g/L and 10 g/L. The adsorption and desorption ability of each ferrite nanoparticles, the effect of heavy metal ion in adsorption and desorption process, and the endurance of ferrite nanoparticles were investigated using atomic absorption spectroscopy (AAS). The removal process has been conducted for wastewater at pH 7.It showed the presence of heavy metal precipitate in solution. The result shows that MgFe2O4 has the highest adsorption ability than other ferrite and MnFe2O4 is the lowest. Desorption ability of all ferrites is high except for Fe ion removal. Desorption of Fe ion shows very low result which might due to FeO bond from Fe ion reaction in acid solution. The endurance of MnFe2O4 and Fe3O4 as adsorbent after repeated adsorption and desorption process is up to 4 times and more than 6 times. The MnFe2O4 nanoparticles show a stability in adsorption ability after 4 times repetition adsorption and desorption process.

scholarly journals Technical Note: Classical and statistical thermodynamic treatment of adsorption and desorption kinetics and rates

2021 ◽  
Author(s):  
Daniel A. Knopf ◽  
Markus Ammann
Keyword(s):  
Chemical Kinetics ◽  
Surface Coverage ◽  
Aerosol Particles ◽  
Statistical Thermodynamic ◽  
Desorption Kinetics ◽  
Desorption Energy ◽  
Desorption Process ◽  
Adsorption And Desorption ◽  
The Impact ◽  
Standard States

Abstract. Adsorption and desorption represent the initial processes of the interaction of gas species with the condensed phase. It has important implications for evaluating heterogeneous (gas-to-solid) and multiphase chemical kinetics involved in catalysis, environmental interfaces, and, in particular, aerosol particles. When describing gas uptake, gas-to-particle partitioning, and the chemical transformation of aerosol particles the desorption lifetime is a crucial parameter to assess the underlying chemical kinetics such as surface reaction and surface-to-bulk transfer. The desorption lifetime, in turn, depends on the desorption free energy which is affected by the chosen adsorbate model and standard states. To assess the impact of those conditions on desorption energy and, thus, desorption lifetime, we provide a complete classical and statistical thermodynamic treatment of the adsorption and desorption process considering transition state theory for two typically applied adsorbate models, the 2D ideal gas and the 2D ideal lattice gas, the latter being equivalent to Langmuir adsorption. Both models apply to solid and liquid substrate surfaces. We derive the thermodynamic and microscopic relationships for adsorption and desorption equilibrium constants, adsorption and desorption rates, first-order adsorption and desorption rate coefficients, and the corresponding pre-exponential factors. Although, some of these derivations can be found in the literature, this study aims to bring all derivations into one place to facilitate the interpretation and analysis of desorption energies for their application in multiphase chemical kinetics. This exercise allows for a microscopic interpretation of the underlying processes including the surface accommodation coefficient and highlights the importance of the choice of adsorbate model and standard states when analyzing and interpreting adsorption and desorption processes. We demonstrate how the choice of adsorbate model choice affects equilibrium surface concentrations and coverages, desorption rates, and decay of the adsorbate species with time. In addition, we show how those results differ when applying a concentration- or activity-based description. Our treatment demonstrates that the pre-exponential factor can differ by orders of magnitude depending on the choice of adsorbate model with similar effects on the desorption lifetime, yielding significant uncertainties in the desorption energy. Furthermore, uncertainties in surface coverage and assumptions in standard surface coverage can lead to significant changes in desorption energies derived from measured desorption rates. Providing a comprehensive thermodynamic and microscopic representation aims to guide theoretical and experimental assessments of desorption energies and estimate potential uncertainties in applied desorption energies and corresponding desorption lifetimes important for improving our understanding of multiphase chemical kinetics.

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