CS2-extraction and FTIR characterization of four low-rank coals from China

Four Chinese low-rank coals were ultrasonically extracted using carbon disulfide, and the raw and extracted coals were characterized by a Fourier transform infrared spectroscopy. The result shows that the extraction yield of the low-rank coals increases with their ranks at a three-step evolution, and it increases suddenly from 0.82% to 3.04% when the carbon content changing only from 79.82% of Shenfu coal to 81.99% of Geting coal. FTIR Characterization of the coals indicates that low-rank coals are rich in functional groups of hydroxyl, carbonyl, aromatic or hetero aromatic ring and single carbon-heteroatom bonding.