Thermochemistry of ion exchange and particle interaction in clay suspensions

Abstract

The measurement of enthalpies of ion exchange for a number of homovalent and heterovalent exchange pairs by titration calorimetry is described. A self-consistent addition to previous measurements on such systems is reported. In addition to the enthalpies of ion exchange the heats of tactoid formation and breakdown were observed. The apparent heat of tactoid formation for the Na–Ca exchange pair is estimated to be −4.9 kJ per equivalent of ion exchange.