Catalytic Extraction And Component Analysis Of Fulvic Acid From Qujing

In this paper,the lignite from Yunnan Qujing was used as the research object,and the effect of different catalysts on the yield of fulvic acid extracted by hydrogen peroxide in the hydrogen peroxide process was explored.The high-purity fulvic acid obtained by the sulfuric acid ethanol method was classified into four components having different relative molecular weights by using a dialysis bag.The composition and structure of each component were initially explored by means of chemical titration and instrumental detection.In-depth study was used of the components of fulvic acid classified by using a dialysis bag.The components with a molecular weight of 500 or less were subdivided into five products with different polarities by an organic solvent method,and the structural information was further studied.Molecular models of components with molecular weights of 500-2500 were constructed to explore the compositional rules of the molecular structure of each component.By studying the effect of different catalysts on the yield of fulvic acid extracted by hydrogen peroxide method from lignite,it was known that the use of catalyst can reduce the activation energy of the reaction,reduce the amount of hydrogen peroxide,reduce the reaction time and improve the yield of fulvic acid.The conditions of the reaction were milder and more economical when using a CuO catalyst.According to the results of single factor experiment and orthogonal experiment,the optimal process conditions for extracting fulvic acid under the condition of CuO catalyst were as follows:hydrogen peroxide concentration was 4.5%,oxygen to coal ratio was 5:1,reaction time was 8 minutes the microwave power was 400 W and the amount of the catalyst was0.02 g.The average yield of fulvic acid under this condition was 37.49%.The optimum conditions for the purification of fulvic acid by the sulfuric acid-ethanol method obtained by orthogonal experiment were as follows:the reaction temperature was 50℃,the reaction time was 50 minutes,the liquid-solid ratio was 14:1,and the acid-solid ratio was 0.08:1.The average yield of purified fulvic acid was 81.79%.As a result of grading the purified fulvic acid by dialysis bag,it was known that fulvic acid was mainly composed of a large amount of organic compounds having a small molecular weight.According to the results of elemental analysis,oxygen-containing functional group detection,infrared analysis and solid ¹³C nuclear magnetic analysis,it was known that the grading of fulvic acid using a dialysis bag didn’t destroy the characteristic functional group structure in the product.Both the fulvic acid and its fractionated products all contain a large amount of oxygen-containing functional groups,of which the carboxyl group content is the highest,and the content of the phenolic hydroxyl group is higher than the alcoholic hydroxyl group.Organic solvent method was used to subdivide the component having a molecular weight of 500 or less in fulvic acid,it can be found that the component contained a large of polar macromolecular organic matter..The product extracted from the mixture of petroleum ether and ethyl acetate as the eluent had the highest content of oxygen-containing functional groups.The molecular model of DFA₂ and DFA₃ was constructed by instrumental analysis of the structural parameters of the model.The chemical formulas were C₄₄H₃₀O₂₅N（Mr=972）and C₅₃H₃₅O₃₁N（Mr=1181）.The benzene ring was the main aromatic structure of the model,the trisubstituted and tetrasubstituted of benzene ring were the main benzene ring substitution modes.The molecular model contained a large number of oxygen-containing functional groups,including carboxyl groups,carbonyl groups,alcoholic hydroxyl groups,phenolic hydroxyl groups and aldehyde groups,of which the carboxyl group content was the highest.The benzene rings were mostly connected by the fatty carbon chain,the carbonyl group and the ether bond.The carboxyl group was mostly located on the aliphatic carbon chain,and a small amount was located on the benzene ring.The model theory infrared spectrum calculated by Gaussian software had a good matching degree with the actual map,indicating that the established model was reliable.