Classification And Application Of Humic Acid Components From Sludge Compost

Humic acid —— a mixture of natural organic matter with various active chemical groups,has functions such as adsorption,complexation and ion exchange,etc..It can interact with various substances in the environment,affecting the ecosystem.Obviously,the active characteristics are closely related to its structure.The initial classification with solvents leaching and re-separation of subclasses components with high performance liquid chromatography,are helpful to the understanding of molecular structure and composition in humic acid,as well as its wider and in-depth application.In addition,the high carbon content of humic acid makes it useful as a carbon-containing precursor for the preparation of carbon dots.This study focus on component separation and application research of humic acid,the main work is as follows:1.Solvent leaching realizes the preliminary classification of humic acid.Comprehensively considering the polarity of the solvent and their solubility to humic acid,four organic solvents,methanol,ethanol,ethyl acetate,and acetonitrile were used for preliminary classification of humic acid.Elemental composition and functional group analysis of the obtained subclasses components were performed.Multiple characterizations suggest that there are fewer aromatic structures,mostly fused aromatics with four rings or more in the subclasses components obtained from methanol and ethanol leaching,and aromatic structures are substituted by hydrophilic oxygen-containing functional groups such as hydroxyl and carboxyl groups.There are more aromatic structures below three rings in the subclasses components obtained from ethanol and ethyl acetate leaching.The lipid structure is the main component in all subclasses components.2.Fourier transform ion cyclotron resonance mass spectrometry was applied to analyze the molecular masses of the four subclasses components.Combined with matching chemical formulas,the chemical structures of some compounds containing only C,H,and O were inferred.The subclasses components were further re-separated and analyzed by high-performance liquid chromatography-mass spectrometry.The results showed that the four subclasses components all contained four higher-content compounds,and the molecular formulas of the compounds were inferred.3.Humic acid was used as the raw material for hydrothermal reaction.Nitrogen-containing carbon dots modified with multifunctional groups was synthesized and its fluorescence effect was explored.X-ray photoelectron spectroscopy analysis showed that the N content in the synthesized nitrogen-containing carbon dots increased.Nitrogen-containing carbon dots has good selectivity to iron ions,with the lowest detection limit of 1.9 n M.At the same time,the paper-based fast sensor can sensitively detect the presence of iron ions.After calculation and testing,it is verified that the fluorescence quenching mechanism is static quenching...