Transport of Low Molecular Weight Anions through a Nafion Ionomer Membrane:  Application to Kraft Cooking Liquors

Abstract

The permeation of low molecular weight anions from liquors having high ionic strengths through a Nafion 811 membrane in Na+ form has been studied. The penetration of solutes through the membrane was monitored using UV-visible spectrometry. A relation between penetration and ionic size has been established. The influence of the presence of other ions on the permeation has also been investigated. The results show that the membrane has great potential as part of a selective interface in applications where the concentration of small anions is to be monitored in media with high ionic strengths. In light of the new results, we have validated a previously developed system for monitoring the concentrations of hydrogen sulfide ion and dissolved lignin in a laboratory-scale kraft cooking system.

Study of the Potentiometric Response of Glassy Carbon Electrodes Coated with the Polycationic Ionomer Tosflex

“…It is normally expected to be permselective and to completely reject cations due to their electrical charge, which is identical to the one of the fixed sites. Actually, as it has been observed for Nafion [14], a slight permeation of cations can occur, especially when the ionic strength of the solutions is high, according to the ™Donnan potential∫ theory.…”

Novel mechanism for the Nafion membrane transfer of anthraquinones

“…However, Danielsson and Yang [5] showed that molecules with molecular weights higher than that of AHQs could diffuse through the membrane. Therefore, it was hypothesized that the electronic structure of the AHQs could have an impact.…”

“…Later data show that there is an inverse relationship between the penetration efficiency of an anionic compound in a tubular Nafion membrane and the molecular weight of that compound [5]. Here, penetration efficiency is defined as the ratio of the concentration in the acceptor stream to the concentration in the donor stream.…”

“…1. The log-log plot of penetration efficiency vs. molecular weight [5]. Data from flow rate of 0.5 mL/min and temperature of 21 • C for inorganic and organic molecules with molecular weight (MW) ranging from 33 to 290 g/mol.…”

“…Therefore, a method which separates the AHQ from the other compounds is desirable. This is the basis for a membrane separationbased analytical system, such as that described by Danielsson and Yang [5].…”