Changes in the hydrophobicity of anthracite coals before and after high temperature heating process

High temperature heating process reduces the content of hydrophobic functional groups (CH and CC) but increases the content of hydrophilic functional groups (CO, CO and COOH) The contact angles of heated anthracite coals are much lower than that of fresh (original) anthracite coal. After the high temperature heating process, anthracite coal surface becomes more hydrophilic.