کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
638876 1456191 2006 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Time characteristics of electromotive force in single-membrane cell for stable and unstable conditions of reconstructing of concentration boundary layers
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی تصفیه و جداسازی
پیش نمایش صفحه اول مقاله
Time characteristics of electromotive force in single-membrane cell for stable and unstable conditions of reconstructing of concentration boundary layers
چکیده انگلیسی

The stability of concentration boundary layers near membrane (CBLs), arising after turning off mechanical stirring of KCl solutions in single-membrane cell with polymer membrane placed in horizontal plane, was studied by measurement of time changes of electromotive force of single-membrane cell (EMF). In the case when solution with low concentration and low density (Cl) was over the membrane and the solution with higher concentration and higher density (Ch) was under the membrane (configuration A) the stable recreation of CBLs by diffusion was observed, which was manifested by gradual and monotonous decrease of EMF after turning off mechanical stirring. The results of the carried out experiment show that character of time changes of EMF for A configuration depends on the quotient of concentrations on the membrane Ch/Cl at the initial moment. Besides, for configuration A the pulsations of EMF were not observed in the whole studied range of concentrations. In the case of opposite location of solutions in relation to the membrane (configuration B) it was stated that for Ch/Cl ≤ 10 time changes of EMF were similar to time changes of EMF in configuration A. For Ch/Cl > 10 time characteristics of EMF for A and B configurations were different. For B configuration and Ch/Cl ≥ 100 the pulsations of EMF, arising in a short time after turning off mechanical stirring, were observed. The pulsations of EMF can be connected with hydrodynamic instability in CBLs. Increase of Ch/Cl caused increase of amplitude and decrease of period of EMF pulsations. Besides, for Ch/Cl > 1000 damping of EMF pulsation was observed, greater for higher Ch/Cl. The interpretation of experimental data was made by means of the Kedem–Katchalsky model, diffusion equation and concentration Rayleigh number.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Membrane Science - Volume 280, Issues 1–2, 1 September 2006, Pages 485–493
نویسندگان
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