Ion Pair Association in Extreme Aqueous Environments: Molecular-based and Electrical Conductance Approaches

摘要

We determined by molecular-based simulation the density profiles of the Na+ a <...a <...a <...Cl- ion-pair association constant in steam environments along three supercritical isotherms to interrogate the behavior of ion speciation in dilute aqueous solutions at extreme conditions. Moreover, we describe a new ultra-sensitive, flow-through electrical-conductance apparatus designed to bridge the gap between the currently lowest steam-density conditions at which we are able experimentally to attain electrical conductance measurements and the theoretically reachable zero-density limit. Finally, we highlight important modeling challenges encountered near the zero-density limit and discuss ways to overcome them.