ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Experimental steady-state permeability studies have been made with non-ionic, anionic and cationic dyes using carboxy cellulose membranes as anionic substrates. The experimental results show that with increasing bulk ionic strength the diffusion velocities of anionic and cationic compounds increase and decrease, respectively. The diffusion behavior of non-ionic compounds is independent of the ionic strength. Empirical relationships have been deduced which fit the permeation data of the anionic compounds. A new concept is introduced which postulates that the diffusion behavior of colons within an anionic membrane is dependent on the basicity of the fixed ionic groups. In substrates with matrix-bound anionic groups of high basicity, such as carboxy cellulose, the permeability behavior is described in terms of a new diffusion mechanism referred to as the “fluctuating” charge mechanism. This concept can provide a semi-quantitative understanding of the different electrostatic obstruction effects which matrix-bound carboxylate and sulfonate groups have on the permeability of colons. The measured permeability of the counter ions is in qualitative agreement with the proposed diffusion model.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760200407
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