Effect of hydrothermal temperature on the optical properties of hydrochar-derived dissolved organic matter and their interactions with copper (II)

• DOI: 10.1007/s42773-024-00353-y
• Publication Date: 2024-06-25T03:52:21Z
• Authors: Licheng Ji; Zhongpu Yu; Qi Cao; Xiangyang Gui; Xingjun Fan; Chengcheng Wei; Fei Jiang; Jie Wang; Fanbin Meng; Feiyue Li; Jianfei Wang
• Keywords: EEM-PARAFAC; Metal complex; Environmental sciences; S; Dissolved organic matter; GE1-350; Agriculture; 01 natural sciences; Hydrochar; Hydrothermal temperature; 0105 earth and related environmental sciences

Abstract Hydrothermal carbonization (HTC) has been regarded as a promising technique for turning wet biomass into hydrochar due to its low energy consumption, exhaust gas emissions, etc. In addition, is an important source of dissolved organic matter (DOM), which plays crucial part in the migration and destiny pollutants environmental medium. However, there are limited studies that focus on factors influence formation DOM hydrochar, such hydrothermal temperature. Therefore, current study comprehensively characterized optical properties within derived from sawdust (HDOM) under different temperatures (150–300 °C) by Ultraviolet–visible (UV–Vis) fluorescence spectroscopy, well complexation characteristic with Cu(II). The findings revealed carbon content HDOM reached peak 37.3 mg L −1 when temperature rose 240 °C then decreased increased. UV–Vis spectroscopy analysis showed absorption capacity at 275 nm increases reaches maximum value °C, indicating high promotes monocyclic aromatic compounds. High enhances aromaticity, hydrophobicity, humification degree HDOM, thus improving stability aromaticity. E3/E4 ratios all greater than 3.5, confirming main component fulvic acid, corresponds 3D-EEM Pearson's correlation coefficient analysis. index (HIX) increased rise (150–240 °C), observed three-dimensional excitation-emission matrix (3D-EEMs). After reaching HIX gradually dropped line trend DOC change. Moreover, bioavailability (BIX) was 1, readily bioavailable. Two microbial humic substances (C1 C4), humic-like substance (C2), protein-like (C3) were discovered integrating 3D-EEMs parallel factor (PARAFAC). Their intensity decreases Cu(II) concentration increases, complexes As rises, binding ability changes significantly, optimum 300 °C. Meanwhile, C2 strongest This research emphasizes significance determining evolution hydrochar-derived DOM, potential heavy metal migration, characteristics features. Graphical