Characterization of fluorescent dissolved organic matter from green macroalgae (Ulva prolifera)-derived biochar by excitation-emission matrix combined with parallel factor and self-organizing maps analyses

This study investigated the effects of various pyrolysis temperatures and extraction salinities on the fluorescence features of DOM from Ulva prolifera-derived biochar under aseptic conditions using fluorescence excitation-emission matrix (EEM) spectroscopy with parallel factor (PARAFAC) analysis and self-organizing maps (SOM). Four humic-like substances and one protein-like substance were identified by the PARAFAC model. The contents and compositions of PARAFAC components depended more on the pyrolysis temperature than on the extraction salinity. A high pyrolysis temperature could enhance the release of humic-like DOM from biochar. Coupling PARAFAC and SOM facilitates the visualization and interpretation of the relationship between the pyrolysis temperature and the fluorescence properties of DOM. These results are valuable for understanding the effects and processes of macroalgal biochar in the possible environmental and industrial applications.