Absorption by polyurethane foams; new method of separation

Abstract

Flexible polyurethane foams can be used as selective absorbents for a number of substances from dilute aqueous solutions. Most of the substances absorbed are those which can be extracted from aqueous solutions by use of liquid diethyl ether, e.g., iodine, benzene, chloroform, and phenol from water; mercury(II) and gold(III) from 0·2M-hydrochloric acid; iron(III), antimony(V), thallium(III), molybdenum(VI), and rhenium(III) from 6M-hydrochloric acid; and uranium(VI) from saturated aluminium nitrate solution. The capacities of different foams for absorption vary, but are of the order of 0·5–1·5 mol kg^–1 foam. Desorption can usually be achieved without difficulty. The separations require simple apparatus and are rapid and specific.

The process has been shown to be absorption rather than adsorption by measuring the surface areas of the foams used. Chemical formulae of some of the absorbed species were investigated by chemical and radiochemical techniques.