scholarly journals Adsorption kinetics and equilibria of two methanol samples with different water content on activated carbon

Adsorption ◽  
2021 ◽  
Author(s):  
Meret Rösler ◽  
Carsten Wedler
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Water Content ◽  
Adsorption Kinetics ◽  
Effective Diffusion ◽  
Diffusion Time ◽  
Transfer Coefficients ◽  
Time Constants ◽  
Pure Sample ◽  
Adsorption Equilibria

AbstractTo investigate the influence of fluid purity on the adsorption properties, adsorption kinetics and adsorption equilibria of two methanol samples with different water content on an activated carbon were studied. The purity of the methanol samples was 98.5% and 99.9%. Measurements were conducted at 298 K and 318 K using a magnetic suspension balance and cover a wide p/p0 range. To determine effective diffusion time constants and mass transfer coefficients, adsorption kinetics were evaluated using an isothermal and a nonisothermal Fickian diffusion model, and the linear driving force model. The pressure dependence of the kinetic parameters was studied and discussed. A small influence of sample purity on the adsorption equilibria was observed, as the purer methanol sample showed slightly higher equilibrium loadings than the less pure sample. However, significantly faster adsorption kinetics were observed for the purer sample at all temperature and pressure conditions. Compared to the less pure sample, the determined effective diffusion time constants and the mass transfer coefficients were up to 98% and 35% higher, respectively.

scholarly journals Heat and mass transfer coefficients and modeling of infrared drying of banana slices

Revista CERES ◽  
2017 ◽  
Vol 64 (5) ◽  
pp. 457-464 ◽  
Author(s):  
Fernanda Machado Baptestini ◽  
Paulo Cesar Corrêa ◽  
Gabriel Henrique Horta de Oliveira ◽  
Fernando Mendes Botelho ◽  
Ana Paula Lelis Rodrigues de Oliveira
Keyword(s):  
Mass Transfer ◽  
Diffusion Coefficient ◽  
Shelf Life ◽  
Heat And Mass Transfer ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Infrared Drying ◽  
Ripening Stages

ABSTRACT Banana is one of the most consumed fruits in the world, having a large part of its production performed in tropical countries. This product possesses a wide range of vitamins and minerals, being an important component of the alimentation worldwide. However, the shelf life of bananas is short, thus requiring procedures to prevent the quality loss and increase the shelf life. One of these procedures widely used is drying. This work aimed to study the infrared drying process of banana slices (cv. Prata) and determine the heat and mass transfer coefficients of this process. In addition, effective diffusion coefficient and relationship between ripening stages of banana and drying were obtained. Banana slices at four different ripening stages were dried using a dryer with infrared heating source with four different temperatures (65, 75, 85, and 95 ºC). Midilli model was the one that best represented infrared drying of banana slices. Heat and mass transfer coefficients varied, respectively, between 46.84 and 70.54 W m-2 K-1 and 0.040 to 0.0632 m s-1 for temperature range, at the different ripening stages. Effective diffusion coefficient ranged from 1.96 to 3.59 × 10-15 m² s-1. Activation energy encountered were 16.392, 29.531, 23.194, and 25.206 kJ mol-1 for 2nd, 3rd, 5th, and 7th ripening stages, respectively. Ripening stages did not affect the infrared drying of bananas.

scholarly journals Modelling of NO adsorption in fixed bed on activated carbon

2011 ◽  
Vol 32 (4) ◽  
pp. 367-377 ◽  
Author(s):  
Lenka Kuboňová ◽  
Lucie Obalová ◽  
Oldřich Vlach ◽  
Ivana Troppová ◽  
Jaroslav Kalousek
Keyword(s):  
Nitric Oxide ◽  
Mass Transfer ◽  
Activated Carbon ◽  
Fixed Bed ◽  
Breakthrough Curves ◽  
Force Model ◽  
Transfer Coefficients ◽  
No Adsorption ◽  
Response Curves ◽  
Mass Transfer Mechanism

Modelling of NO adsorption in fixed bed on activated carbon Adsorption experiments of nitric oxide in nitrogen carrier gas were held on activated carbon in a fixed bed flow system. Breakthrough curves describing the dependence of exit concentrations of nitric oxide on time were matched with theoretical response curves calculated from the linear driving force model (LDF). The model assumes Langmuir adsorption isotherm for the description of non-linear equilibrium and overall mass transfer coefficient for mass transfer mechanism. Overall mass transfer coefficients were obtained by the method of least squares for fitting numerically modelled breakthrough curves with experimental breakthrough curves. It was found that LDF model fits all the breakthrough curves and it is a useful tool for modelling purposes.

Relationship between the Activated Carbon Surface Area and Adsorption Model Coefficients for Removal of Phenol from Water

1995 ◽  
Vol 30 (2) ◽  
pp. 325-338 ◽  
Author(s):  
Peter Samaras ◽  
Evan Diamadopoulos ◽  
George P. Sakellaropoulos
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Surface Area ◽  
Activated Carbons ◽  
Carbon Surface ◽  
Adsorptive Capacity ◽  
Mineral Matter ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients ◽  
Commercial Carbon

Abstract The present study investigated the relationship between the activated carbon surface area, as measured by the BET nitrogen adsorption method, and its adsorptive capacity. Aqueous solutions of phenol at pH 7 were used. The activated carbons were produced in the laboratory from raw and demineralized lignite. Adsorption experiments took place under equilibrium or kinetic conditions and the results were simulated by mathematical modelling. Freundlich and Langmuir models were used to describe equilibrium, while the Peel-Benedek non-equilibrium model was applied for the kinetic study. The results showed that for activated carbons produced from different starting materials, the adsorptive capacities could not be solely explained by their BET surface area. While laboratory-made activated carbons with a surface area of 300 m2/g demonstrated similar capacities under equilibrium, their kinetic behaviour was different. Activated carbon produced from raw lignite showed faster kinetics, due to wider porosity, which was facilitated by the mineral matter during activation. These results were in agreement with the mass transfer coefficients in macropores and micropores estimated by the Peel-Benedek model. Comparison of a laboratory-made activated carbon, with a surface area of 500m2/g, with a commercial activated carbon having twice the surface area showed that the maximum adsorptive capacity under equilibrium of the commercial carbon was only 35% higher than that of the lab-made carbon. Yet, the mass transfer coefficients of the commercial carbon were one to two orders of magnitude higher than those of the laboratory-produced carbon. Finally, the use of the qualitative D-R plots has been suggested to elucidate the porous structure of the activated carbons.

Mass Transfer Coefficients in Cryosorption of Hydrogen Isotopes on Molecular Sieves or Activated Carbon at 77 K

1995 ◽  
Vol 28 (3P1) ◽  
pp. 717-722 ◽  
Author(s):  
Masabumi Nishikawa ◽  
Mitsuru Uetake ◽  
Ken-ichi Tanaka ◽  
Tomofumi Shiraishi
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Molecular Sieves ◽  
Hydrogen Isotopes ◽  
Transfer Coefficients ◽  
Mass Transfer Coefficients

scholarly journals Mass Transfer and Adsorption Kinetics of Phenolic Compounds onto Activated Carbon Prepared from Rice Husk

2008 ◽  
Vol 26 (3) ◽  
pp. 157-167 ◽  
Author(s):  
Mamdouh M. Nassar ◽  
Yehia H. Magdy ◽  
Abd El Hakim Daifullah ◽  
H. Kelany
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Phenolic Compounds ◽  
Rice Husk ◽  
Adsorption Kinetics ◽  
Kinetics Of

scholarly journals THE USER OF ADSORPTION FOR PURIFICATION OF WASTEWATER FROM THE PRODUCTION OF PHENOL-FORMALDEHYDE RESINS

2016 ◽  
pp. 26-33
Author(s):  
Irina Timoshchuk ◽  
Irina Timoshchuk
Keyword(s):  
Mass Transfer ◽  
Activated Carbon ◽  
Phenol Formaldehyde ◽  
Fixed Bed ◽  
Experimental Studies ◽  
Feed Water ◽  
Organic Substances ◽  
Transfer Coefficients ◽  
Carbon Sorbents ◽  
Diffusion Dynamics

To increase ecological safety of phenol-formaldehyde resins production of the novolac type, the adsorption technology for purification of wastewater containing mainly phenol and formaldehyde was developed. The research of organic substances adsorption (formaldehyde, phenol) from individual aqueous solutions and their mixtures on carbon sorbents grades AG-3, AG-OV-1, SKD-515, BAU, ABG, XAU was conducted, this grades differ in composition, method of producing, structure, and chemical state of the surface. The basic laws, characteristics and mechanism of adsorption of organic substances on activated carbon (AU) were established. The mechanism of mass transfer during adsorption of a mixture of phenol and formaldehyde on the investigated sorbents was showed, and the external mass transfer coefficients were calculated. There was proposed the method of optimization of parameters and continuous adsorption treatment process modes, based on the fundamental external diffusion dynamics adsorption formula using the adsorption constants of the Dubinin-Radushkevich’s equation and kinetic dependencies. The main features of the adsorption dynamics were established, which allowed to determine the duration of column operation, the amount of feed water depending on the throughput rate, the height of the fixed bed and size of the column. According to the results of experimental studies and derivatographic analysis we developed the technology of carbon sorbents regeneration after adsorption of formaldehyde and phenol mixture, which allowed to restore the AC (activated carbon) sorption capacity to 95-98%. On the basis of aggregate balance studies, kinetics and dynamics of adsorption process, optimization of the cleaning regime and the parameters of adsorption column using mathematical modeling, we recommend the technological solution for waste water purification from phenol and formaldehyde, which are formed in the process of phenol-formaldehyde resins of the novolac type production.

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