Structure and dynamics in brown coal matrix during moisture removal process by molecular dynamics simulation

A molecular dynamics simulation study of a brown coal matrix with a moisture content ranging from 0 to 60% was performed to examine the structure and dynamics of the coal-water system. The simulations show that the brown coal matrix shrinks during the drying process. The water molecules prefer to interact with hydrophilic oxygen moieties. During the drying process, the removal of water occurs successively from the outer hydration shell to the inner hydration shell around the oxygen moieties. The translational and rotational mobilities of water are found to be slower with the decrease of moisture content and in the proximity of carboxyl and carbonyl groups.