SELECTIVITY OF A POLYSTYRENEBENZYLTRIMETHYLAMMONIUM-TYPE ANION-EXCHANGE RESIN FOR ALKANESULFONATES

The selectivity sequence for the series of n-alkanesulfonates (sodium salts) through n-heptanesulfonate was determined with analytical grade Dowex-1 type resin (chloride form) of 1, 4, 8, and 10% nominal DVB content The variation of selectivity with resin loading and temperature was studied with the 8% cross-linked exchanger. Changes in selectivity behavior due to added organic solvents or urea were observed using 4 and 8% cross-linked resins. In aqueous media, selectivity was found to increase with increasing chain length of the counterions. Thermodynamic quantities were estimated from the selectivity data obtained at different temperatures. The exchange process Cl- + RSO3- ⇄ RSO3- + Cl- was found to be entropy-directed for alkanesulfonates having a hydrocarbon tail consisting of more than four chain links. Hydrophobic interactions in the (external) aqueous solution phase are suggested as an important factor in controlling amonexchange resin selectivity for this family of aliphatic counterions.