Über das sorptionsverhalten von kationenaustauschern auf polystyrolbasis in wässrigem dioxan bzw. dimethylsulfoxid

Abstract

This study deals with the sorption behaviour of a number of cation exchangers in dioxan—water as well as dimethylsulphoxide—water mixtures. The lower the concentration of water in the surrounding solution, the more water will be relatively absorbed by the exchanger. Both the amount and composition of the inner solution are strongly influenced by pore structure, cross-linking and load of the exchanger. Macroreticular ion exchangers absorb great amounts of solvents over the entire concentration range. The absolute sorption of water decreases with increasing degree of cross-linking of the exchanger, while the selectivity increases. The selectivity of the counter-ions for water increases in the sequence Na + < Ca 2+ < Zr(IV) < Al 3+. A decisive factor is the charge of counter-ion; Zr(IV) acts as a cation with a charge of 2+. The polarity of the solvent phase has a large influence on the sorption. A preparative method of carefully dehydrating ion exchangers is described. According to the kind of exchanger the residue water is between 100–1000 p.p.m. The amount of water in macroreticular exchangers is about double that in the conventional type of exchanger.