Md. Reboiras, ELECTROCHEMICAL PROPERTIES OF CELLULOSIC ION-EXCHANGE MEMBRANES .2. TRANSPORT NUMBERS OF IONS AND ELECTROOSMOTIC FLOW, Journal of membrane science, 109(1), 1996, pp. 55-63
Transport numbers of counter-ions in cellulosic cation- and anion-exch
ange membranes have been determined by both emf and Hittorf's methods
for various (1:1)-electrolytes at different concentrations. The transp
ort number derived from the emf data, in general, is lower than the va
lue obtained by the Hittorf method, for any given external electrolyte
concentration. This difference is attributed to transport of water oc
curring across the membrane. Electro-osmotic water transport across th
e membranes in equilibrium with several electrolytes has been determin
ed at different concentrations. The data obtained have been interprete
d in terms of the hydrated ion size of the counter-ions. Volume flow a
nd electrical conductance across the membranes in the presence of vari
ous electrolytes have been measured at several electrical potential di
fferences. The experimental results have been interpreted in terms of
linear phenomenological equations. These relationships have been used
to estimate the magnitudes of the phenomenological coefficients for vo
lume flow and conductance across the cationic and anionic membranes. T
he validity of the phenomenological equation in volume flow across the
membranes has been tested by comparison with the data obtained by dir
ect measurements.