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Effects of grain‐scale mass transfer on the transport of volatile organics through sediments: 1. Model development
Author(s) -
Cunningham Jeffrey A.,
Werth Charles J.,
Reinhard Martin,
Roberts Paul V.
Publication year - 1997
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/97wr02425
Subject(s) - diffusion , mass transfer , sorption , scale (ratio) , statistical physics , non equilibrium thermodynamics , limiting , diffusion process , grain boundary diffusion coefficient , thermodynamics , boundary value problem , grain boundary , mechanics , chemical physics , materials science , chemistry , physics , mathematics , computer science , innovation diffusion , engineering , mathematical analysis , metallurgy , mechanical engineering , knowledge management , microstructure , adsorption , quantum mechanics
In the first paper of this two‐paper series, we present a new model that attributes nonequilibrium sorption of moderately hydrophobia, volatile organic compounds to intragranular diffusion. The model differs from those of previous researchers in that for the first time, it combines the following elements: (1) We account for two distinct intragranular rate‐limiting diffusion processes, occurring in series and at widely different timescales; (2) we describe the slower of the two processes with a gamma distribution of diffusion rates; and (3) we use the disparity of timescales of the two processes to approximate a boundary condition for the distributed diffusion equation, allowing it to be solved analytically. The slower diffusion process is attributed to activated diffusion through very small pores, called micropores. In paper 2 [ Werth et al. , this issue] we evaluate the capabilities of the model and use it to interpret experimental results.