Study On The Distribution Of Non-acidic Groups Of Fulvic Acid From Hulunbuir Lignite

Lignite which was from Inner Mongolia Hulunbeier was chosen as the study subject.Using hydrogen peroxide oxidation and sulfuric acid-acetone purification method can obtain high-purity fulvic acid and the content of non-acidic functional groups such as alcoholic hydroxyl,carbonyl,methoxy,primary amino group and sulfydryl,which were detected by chemical analysis methods.The fulvic acid was characterized by elemental analysis,FT-IR,UV/Vis,XPS and ¹³C-NMR.The structural parameters of fulvic acid were obtained by combining chemical analysis methods and instrumental analysis.The structural parameters were simulated by quantum chemical calculation to obtain the optimal molecular structure model of fulvic acid.The hydrogen peroxide was used to extract fulvic acid in the case of microwave.Based on the single factor,the response surface experiment was carried out to obtain the optimal conditions for extracting fulvic acid:oxygen-coal ratio was 9,the concentration of hydrogen peroxide was 18%,reaction time was 14min and the microwave power was 600W,the yield of FA₁ was 22.13%under the optimal conditions.The optimal conditions for purification of fulvic acid by the response surface experiment:the ratio of sulfuric was 0.06,the liquid-to-solid ratio was 7,reaction tempture was 41?and reaction time was 68min,the yield of FA_1P was 64.48%under the optimal conditions.The contents of non-acidic functional groups of fulvic acid were obtained by chemical analysis,in which the content of alcoholic hydroxyl was 6.92mmol/L,the percentage of quality of carbonyl was 0.81%,the percentage of quality of methoxy was 0.18%,the percentage of quality of the primary amino group was 0.02%and the percentage of quality of sulfydryl was 0.13%.The fulvic acid was characterized by elemental analysis,FT-IR,UV/Vis,XPS and ¹³C-NMR.By FT-IR,the attribution and relative content of the functional groups in the fulvic acid structure were obtained.The structural parameters of fulvic acid molecular model were obtained based on the infrared analysis data:hydrogen rate,aliphatic chain length,hydrogen-carbon atom ratio,and aromatic carbon ratio.Based on the results of UV/Vis,high purity fulvic acid has a high degree of aromaticity,degree of humification and conjugate degree of carbonyl.The presence of surface elements of fulvic acid structure was obtained by XPS.¹³C-NMR analysis showed the assignment of carbon atoms with different chemical shifts in the molecular structure of fulvic acid,which provided carbon skeleton and structural parameters for the construction of the molecular model of fulvic acid.Combined elemental analysis,chemical analysis,FT-IR and¹³C-NMR,the structural parameters of fulvic acid molecular model were obtained.The average molecular formula of the constructed fulvic acid molecular model was C₄₆H₃₈O₂₀NS,Mr=956.The Gaussian 09W which based on the Ground State?HF/3-21G and Default Spin was carried out to optimize the molecular structure model of fulvic acid by quantum chemical calculations and the theoretically calculated frequency spectrum has a high degree of matching with the experimental spectrum.