Weak interaction between water molecule and different rank coals: a DFT-D3 study

Abstract

Weak interaction between water molecules with different rank coals(anthracite, bituminous, subbituminous and lignite) was studied by density functional theory with dispersion correction (DFT-D3) in quantum chemistry method. The equilibrium configurations of water molecule on the surface of coal molecules were optimised, analysis of electrostatic potential on the surface of coal molecule was conducted, and interaction energy between coal molecular surface and water molecular was calculated, as well as interaction types of water on the different rank coals molecular surface were confirmed by calculating the reduced density gradient function (RDG). Research shows that the order of maximum adsorption interaction energy is lignite > subbituminous > bituminous > anthracite, and the hydrogen bond and Van der Waals play a dominant role in the adsorption of water on coal molecule surface. [Received: June 17, 2016; Accepted: March 22, 2017]