水热腐殖化人工腐殖质的光谱和电化学特性研究OA北大核心CSTPCD

Humic substances(HS)are natural organic materials formed through the decomposition of plant and animal remains and the slow transformation by microbes.Rapid production of HS can be achieved through hydrothermal treatment of biomass;however,the research on the spectroscopic and electrochemical properties of artificial humic substances is still insufficient.In this study,artificial humic acid(AHA)and artificial fulvic acid(AFA)were prepared using corn straw as a raw material through a hydrothermal humification method.Their chemical structures and molecular composition were analyzed through spectroscopy and high-resolution mass spectrometry and compared with humic acid and fulvic acid from black soil and peat soil.Electrochemical analysis was employed to measure the electron accepting capacity(EAC)and electron donating capacity(EDC)of HS.The spectral and mass spectrometry results revealed that the artificial HS is highly consistent with natural HS in chemical structure,presenting the same major chemical groups,including hydroxyl,aliphatic,aromatic,and carboxy ketone groups.Moreover,artificial HS exhibited higher fluorescence indices and lower aromaticity,and were rich in tyrosine-like fluorescent components.Both artificial and natural HS primarily contain lignin/carboxylic-rich alicyclic structures,lipids,and aliphatic/proteinaceous materials.The electrochemical results indicated that AHA had an EAC of 1.85 mmol·g-1,higher than natural humic acid,and an EDC of 0.5 mmol·g-1,which is comparable to natural humic acid.AFA had an EAC of 2.07 mmol·g-1,lower than natural fulvic acid,but an EDC of 0.66 mmol·g-1,higher than natural fulvic acid.The analysis of correlation revealed that the electron transfer capacity is significantly influenced by the content of lignin/carboxylic-rich alicyclic molecules(CRAM)and lipids.It was found that tyrosine-like fluorescent components and nitrogen-containing organic compounds(CHON)have a positive correlation with electron donating capacity(EDC).Conversely,humic-like fluorescent components,the atomic ratio of oxygen to carbon(O/C),and double bond equivalents(DBE)showed a positive correlation with electron accepting capacity(EAC).This study confirmed that artificial HS possess noteworthy electrochemical characteristics.Furthermore,the research enhances our comprehension of the ability of artificial HS to mimic the functions of natural HS,especially in their role in geochemical electron transfer processes.