Comparison of some physico–chemical properties of Victorian lignite dewatered under non-evaporative conditions

Chemical and structural changes in XiMeng lignite and its carbon migration during hydrothermal dewatering

“…Thus, the water-holding capacity of coal is considerably reduced after removal of these functional groups. It is of interest to note that the coals after HTD modification might be considered to be somewhat analogous to higher-rank coals, and HTD can be regarded as somewhat analogous to the coalification process although considerably accelerated by the temperature and pressure applied [21].…”

Upgrading of low rank coal by hydrothermal treatment: Coal tar yield during pyrolysis

“…The water can participate in one or more roles with the existing of oxygen functional groups [12] in brown coal: as a catalyst, reactant, and solvent in the aquathermolysis chemistry at the treatment temperature. Compared with these methods, hydrothermal treatment was considered as an effective pretreatment method [13][14][15]. Water removed as liquid may dissolve and leach out some water soluble inorganics and hydrophilic organics containing oxygen functional groups with the waste water, thereby reducing the amount of ash producing constituents [16] and oxygen functional groups [17] in the upgraded solid during hydrothermal treatment.…”

Physicochemical properties of wastewater produced from the microwave upgrading process of Indonesian lignite

“…The latter is believed to be bonded to acidic functional groups, such as carboxyl and phenolic hydroxyl groups in lignite [54]. Cations present as dissolved salt were released in proportion to the amount of water removed [55,56]. With increased microwave time, more cations were released because of the decomposition of acid groups on which some cations were exchanged [57].…”