Open AccessThe selective properties of the copper ferrocyanide membrane
Publication year - 1917
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1917.0018
Subject(s) - ferrocyanide , membrane , potassium ferrocyanide , copper , colloid , adsorption , chemistry , sugar , chemical engineering , capillary action , chromatography , inorganic chemistry , materials science , organic chemistry , composite material , biochemistry , electrode , engineering
In a previous research dealing with the structure of semi-permeable membranes, it has been shown that the copper ferrocyanide membrane is built up from colloidal particles having diameters ranging from 50 to 400μμ ; also that the pores enclosed by these particles have an average diameter which, although large enough to allow passage to any non-colloidal molecule, is small enough to be entirely within the range of capillary effects. On the basis of these facts the hypothesis was advanced that the selective properties of colloidal membranes are due to selective adsorption; a copper ferrocyanide membrane immersed in cane-sugar solution, for instance, being permeable to the water and not to the cane sugar, because the water, rather than the sugar, is selectively adsorbed or “condensed” on to the membrane surface and into its capillaries. The present research is an experimental investigation of this view. The measurements made herein consist in a determination of the change in concentration brought about by immersing more or less dry colloidal copper ferrocyanide in cane-sugar solutions of various strengths. The results obtained tend to confirm the adsorption hypothesis for this case at least.