Solvent Sorption of Ion-Exchange Resins in Nonaqueous Solvents

Abstract

Solvent sorption properties for sulfonated ion-exchange resins in nonaqueous solvents, by comparing them with those for unsulfonated resins, were investigated. Seventeen polar and nonpolar organic solvents were used and the resins used were of gel and macroreticular (MR) types.
The solvent sorption of ion-exchange resins (Dowex 50 WX 8 of gel type and Amberlyst 15 of MR type) is stronger for MR type resin, retaining a rigid and porous structure, than for gel type resin. The swelling of these resins increases with increasing solubility parameter of the solvents (δ1 ) in δ1≥10 for H-form or δ1≥12 for Na-form, and does not increase in the solvents, whose 8, is less than the above value. These were considered to be due to the interac- tion between solvents and sulfonate groups in the resin. The correlation between swelling properties of resins and solvent properties, such as dielectric constant, dipole moment, and donor number, was not good.
The swelling properties of unsulfonated resins differ from those of the sulfonated ion-exchange resins. The swelling of gel-type polystyrenes with 1 and 8% divinylbenzene contents is the strongest in the solvent with δ1=9. On the other hand, MR-type Amberlite XAD resin (styrene-divinylbenzene copolymer) adsorbs any solvents tested equally in the pore of the resin, and hence, the swelling was scarecely observed.