The adsorption of dyes in chitin. III. Intraparticle diffusion processes

1983 ◽  
Vol 28 (5) ◽  
pp. 1767-1778 ◽  
Author(s):  
G. McKay ◽  
H. S. Blair ◽  
J. Gardner
Keyword(s):  
Diffusion Processes ◽  
Intraparticle Diffusion

Intraparticle diffusion processes during acid dye adsorption onto chitosan

2007 ◽  
Vol 98 (15) ◽  
pp. 2897-2904 ◽  
Author(s):  
W.H. Cheung ◽  
Y.S. Szeto ◽  
G. McKay
Keyword(s):  
Diffusion Processes ◽  
Dye Adsorption ◽  
Intraparticle Diffusion ◽  
Acid Dye

Experimental design of diffusion and desorption of contaminant in heterogeneous media

2011 ◽  
Vol 64 (4) ◽  
pp. 988-998
Author(s):  
Guannan Jiang ◽  
Michelle Crimi ◽  
Kathleen Fowler ◽  
Xiaojing Fu
Keyword(s):  
Experimental Design ◽  
Heterogeneous Media ◽  
Diffusion Processes ◽  
Experimental System ◽  
Intraparticle Diffusion ◽  
Transport Processes ◽  
Low Permeability ◽  
Site Assessment ◽  
Treatment Volume ◽  
The Impact

Storage of contaminants in low permeability media (LPM) presents a great challenge for prediction of remediation effectiveness and efficiency. The reason lies in the contaminants' complex behaviors within heterogeneous media. Both interparticle and intraparticle diffusion contribute to the difficulty of precise site assessment. Sorption of contaminants – especially within LPM – may sequester the contaminants from active treatment, while desorption over a long period of time leads to contaminant release from storage and consequent re-contamination. Research has been conducted toward better understanding of contaminant diffusion and sorption/desorption processes to better predict contaminant response to site treatment. However, most of the research has been carried out within homogeneous media, while real scenarios in environmental problems feature media whose permeability and other characteristics vary significantly over the treatment volume. Further, few efforts have combined the interparticle/intraparticle diffusion and sorption/desorption processes together. This research aims at a feasible experimental design of diffusion and desorption of contaminant in heterogeneous media to address the gaps in previous research. A 2-D experimental system was designed to evaluate interparticle/intraparticle diffusion processes of trichloroethylene (TCE) in heterogeneous media. The 2-D system was modified to include organic matter in media for simulation of sorption/desorption processes. Results of the research will improve the understanding of how these different transport processes act together within heterogeneous media. Results will also allow for the evaluation of the impact of contaminant mass transport from within low permeability media at a potential treatment site and can support the development of mathematical tools/models combining interparticle/intraparticle and sorption/desorption processes. Such a model will promote more accurate site assessment and provide more confidence in the choice of an effective, economically optimized remediation strategy.

scholarly journals Endüstriyel Sızıntı Suyundan Pb(II) Giderimi İçin Genleştirilmiş Perlit Kullanımı: Kinetik Çalışmalar

2018 ◽  
Vol 6 (3) ◽  
pp. 360
Author(s):  
Fulya Aydın Temel
Keyword(s):  
Kinetic Models ◽  
Diffusion Processes ◽  
Intraparticle Diffusion ◽  
Second Order ◽  
Expanded Perlite ◽  
Film Diffusion ◽  
Intraparticle Diffusion Model ◽  
Effects Of Ph ◽  
Pseudo Second Order ◽  
One Step

In this study, the removal efficiency of Pb(II) from industrial leachate was investigated by using expanded perlite by adsorption. The effects of pH, contact time, and adsorbent dosage were examined on the Pb(II) removal. The adsorption kinetics were tested to understand the adsorption mechanism using three kinetic models, i.e., Elovich, intraparticle diffusion, and the pseudo second order reaction kinetic models. As the result, the best conformity kinetic model for Pb(II) adsorption on expanded perlite was described as the pseudo second-order (R2>0.99). It is indicated that chemisorption is the determining step of adsorption process rather than mass transfer from industrial leachate. According to the data obtained from intraparticle diffusion model, the adsorption is composed of more than one step. This can be attributed to the fact that the adsorption in the final portion was the intraparticle diffusion while the adsorption in the first portion was the film diffusion. Both film diffusion and intraparticle diffusion processes in the adsorption of Pb(II) on expanded perlite are significant. This study indicated that expanded perlite was an influential alternative adsorbent for the removal of Pb(II) by adsorption from industrial leachate.

Meridional Circulation, Turbulence, and Diffusion Processes in Stars

1976 ◽  
Vol 32 ◽  
pp. 109-116 ◽  
Author(s):  
S. Vauclair
Keyword(s):  
Convection Zone ◽  
Diffusion Processes ◽  
Meridional Circulation ◽  
Diffusion Time ◽  
Work In Progress ◽  
First Results ◽  
Stellar Envelopes ◽  
And Diffusion ◽  
Turbulence And Diffusion ◽  
Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

Ergodic Control of Diffusion Processes

2009 ◽  
Author(s):  
Ari Arapostathis ◽  
Vivek S. Borkar ◽  
Mrinal K. Ghosh
Keyword(s):  
Diffusion Processes ◽  
Ergodic Control

NMR-Study of Structure and Diffusion Processes in Li3N

1980 ◽  
Vol 41 (C6) ◽  
pp. C6-28-C6-31 ◽  
Author(s):  
R. Messer ◽  
H. Birli ◽  
K. Differt
Keyword(s):  
Diffusion Processes ◽  
Nmr Study ◽  
And Diffusion
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