Very large thermal separations for polyelectrolytes in salt solutions

Abstract

A conductivity method is used to measure the Soret coefficient and heat of transport of aqueous sodium poly(styrenesulfonate)(Na_nPSSA). The data are used to calculate thermal separation factors for Na_nPSSA dissolved in aqueous sodium chloride solutions. The calculations show that large steady-state concentration gradients in the polyelectrolyte will be established when a temperature gradient is applied to mixed Na_nPSSA–NaCl solutions, ranging up to 80% change in concentration per degree as the polyelectrolyte concentration approaches zero. The Soret coefficient and heat of transport of aqueous sodium benzenesulfonate are measured and compared with the corresponding values for Na_nPSSA.