Volume of Space within Cation-exchange Resins Determined by Penetration of Inorganic Salt Solutions

Abstract

Penetration of salt solutions into cation exchange resins was used to measure the volume of a space within the resin phase (the inner space), which was usable for ion exchange in principle but not fully in practice. The average volume of the inner space per functional group was significantly dependent on the type and the concentration of the salt (250-450 Å 3) for a resin having the cross-linking degree of 8%, while being less dependent on the type and the concentration of the salt (160-240 Å 3) for a resin having the cross-linking degree of 12%. The salt concentration ratio of the solution filling the inner space to the outer solution decreased with a decrease in concentration of the outer salt solution due to the osmotic pressure, and decreased with an increase in cross-linking degree due to the smaller volume and the higher independency of the inner space.

Slow, Mid-saturated Exchanges by Large Anions on Resins due to Increase in Independency of Exchange Sites with Cross-Linking

“…Under these conditions, the resins were maximally swollen within the limitations of cross linking. The volume of I × 8 is comparable to but slightly smaller than the corresponding value (350 Å 3 ) of the CXR in the Na form, 15 probably due to the difference in size between the trimethylbenzylammonium group and the benzenesulfonate group.…”

“…16 The water contents of the AXRs equilibrated at a relative humidity of 100% were also determined to estimate the average volume of the exchange site, Vxs, as described elsewhere. 15 Nine benzenesulfonate derivatives, five benzoate derivatives, and two phenolate derivatives of different sizes were used as AA. The abbreviations and the volumes of AAs (VAA) in the acid form in Å 3 S1, Supporting Information).…”

“…14 Furthermore, we have determined such volumes by using penetration of salt solutions into the resin phase. 15 The average volume of the exchange site (Vxs) becomes smaller with an increase in concentration of the salt solution (from 450 to 250 Å 3 for the CXR at the CL-degree of 8%, from 240 to 160 Å 3 for the CXR at the CL-degree of 12%). The volume is smaller, and the exchange site is more independent, with regard to the CXR at the higher CL-degree.…”

Xylitol Separation from a Polyol Mixture Using Lanthanide Ion-loaded Resins

“…Now we can choose the suitable resin appropriate for our research purpose considering several requirements regarding, for example, the types of cations (hard or soft) and how to use the resin (reversible or irreversible binding). [25][26][27][28] Here we chose AG 50W-X4, which is a strong-acid cation-exchange resin with sulfonic acid groups. Seven Ln 3+ from lanthanide series, La 3+ , Ce 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Ho 3+ , and Yb 3+ , were loaded on the resin using the column method.…”