摘要: Naomaohu sub-bituminous (NS) with weak reducibility and Buliangou sub-bituminous (BS) with strong reducibility were extracted in isometric carbon disulfide/acetone mixed solvent to get extracts and extraction residues (ERs). The ERs were thermal dissolved in cyclohexane and methanol to get soluble portions (SPs). The yields of the extracts from NS (ENS) and BS (EBS) are 10.6% and 8.0%, respectively, and the total yields of the SPs from NS and BS at 300℃ are 36.3% and 11.5%, respectively, indicating the solubility of the organic species in NS are better than that in BS. Arenes are the dominated compounds both in ENS and EBS. The relative contents of aliphatic hydrocarbons and phenols in the SPs of NS are obvious higher than those of BS. The molecular weight distribution of the compounds in ENS is wider than that in EBS, while the molecular weight distribution of the compounds in the SPs from NS is narrower than that from BS.
摘要: In order to understand the effects of solvent pretreatment on the inherent macromolecular structure of low rank coal, Xilinguole lignite (XLL) and Shenfu sub-bituminous coal (SFC) were extracted by tetrahydrofuran (THF) soxhlet extraction, carbon disulfide/N-methyl-2-pyrrolidone (CS2/NMP) mixed solvent extraction and thermal dissolution, respectively. The extracted coals were characterized by diffuse reflection FT-IR spectroscopy (DRIFT), thermogravimetric analysis (TGA), mercury intrusion method (MI) and swelling ratio determination. The results indicated that the extraction resulted in the arrangement and reassociation of coal inherent macromolecules. THF Soxhlet extraction and CS2/NMP mixed solvent extraction can relax the macromolecular structure of coal to varying degrees by changing the non-covalent bond cross-linking, especially the distribution of hydrogen bond interactions. However, thermal dissolutions at high temperature mainly increased the covalent cross linking of coal macromolecules, especially for XLL. Swelling of all extracted coals was limited by Fickian diffusion, and the extracted coal showed lower swelling activation energy than the corresponding raw coals.
摘要: Various graphitic carbon nitride (g-C3N4) materials having nitrogen defects were synthesized by adding NaHCO3 during the thermal polymerization of melamine. The as-prepared g-C3N4 samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption-desorption, X-ray photoelectron spectroscopy (XPS), UV-visual diffuse reflectance spectroscopy (UV-vis DRS) and photoluminescence spectroscopy (PL); their photocatalytic activity in the degradation of Rhodamine B (RhB) under visible light irradiation was investigated. The results demonstrated that the unique nitrogen defects in g-C3N4 play an important role in broadening the absorption of visible light and enhancing the separation of electron-hole pairs. The photocatalytic activity of g-C3N4 with nitrogen defects is enhanced greatly; the RhB removal rates over the CNK0.005, CNK0.01, and CNK0.05 photocatalysts in 30 min reach 79.8%, 100.0% and 87.6%, respectively. In contrast, the pristine g-C3N4 free of nitrogen defects only gives an RhB degration rate of 59.8% under the same reaction conditions.