Study On The Structure Of Shengli Lignite And Construction Of The Molecular Structure Models Of The Humic Acids In Shengli Lignite

Shengli lignite was chosen as the study subject, which was treated by hydrogen peroxide and sodium hydroxide solution respectively. The structure property of oxidized lignite, the extractive and the lignite treated by alkali were studied by elemental analysis, FT-IR, TG, TG/GC/MS. The samples of lignite were conducted the absorption water experiment. The extractive(humic acid) extracted by alkali treatment was separated, through which the ulmic acid and humus were got. Then the molecular structure models of ulmic acid and humus were constructed by summarizing the results of some modern analytical tests.(1) After treated by hydrogen peroxide, the content of carbon of oxidized lignite was decreased, the aryl-ether bands are cleavage to alkyl ether bands and alcoholic hydroxyl groups. This kind of oxidation removed some sulfur and nitrogen. The extractive was abundant with oxygen-containing functional group. The molecular of extractive mainly was fatty acid, which was prone to be pyrolyzed. The absorption water ability of oxided lignite was lower than lignite, which meaned that oxidation treatment could strengthen the interface stability of lignite.(2) The model structure of ulmic acid was established by means of elemental analysis, FT-IR, TG/GC/MS and 13 C NMR analysis. The molecular formula of ulmic acid fragment was C89H73NO40, which was good matched with the elemental analysis result. The characteristics of the structure unit model: the structure was rich in aromatic ring, the bridged linkage was mainly of ether bond, oxygen-containing functional group was mostly phenolic hydroxyl group and carbonyl, fatty chain was in the form of short chain. Gaussian computation was used to optimize the constructed structure and the calculated FT-IR spectrogram was generally matched with the experimental spectrogram.(3) The model structure of humus acid was established by means of elemental analysis, FT-IR, TG/GC/MS and 13 C NMR analysis. The molecular formula of humus acid fragment was assured as C148H118N2O66, which was good matched with the elemental analysis result. The characteristics of the structure unit model were similar with ulmic acid. Gaussian computation was also used to optimize the constructed structure and the calculated FT-IR spectrogram was generally fit the experimental spectrogram.(4) After being extracted humic acid, the carbon content of lignite was decreased and the oxygen content was increased. This kind of treatment broke the ether bond. The material which was easily pyrolyzed almost been extracted by sodium hydroxide solution and the some sulfur was been removed. However the macromolecular skeleton wasn’t damaged seriously. The treated lignite was rich in single benzene rings.