Enhanced heating of salty water and ice under microwaves: Molecular dynamics study

By molecular dynamics simulations, we have studied the enhanced heating process of salty ice and water by the electric field of applied microwaves at 2.5 GHz, and those in the range 2.5-10 GHz for the frequency dependence. We show that water molecules in salty ice are allowed to rotate in response to the microwave electric field to the extent comparable to those in pure water, because the molecules in salty ice are loosely tied by hydrogen bonds with adjacent molecules unlike the case of rigidly bonded pure ice. The weakening of hydrogen-bonded network of molecules in salty ice is mainly caused by the electrostatic effect of salt ions rather than the short-range geometrical (atom size) effect of salt ions since the presence of salt ions with small radii results in similar enhanced heating.