Bisphenol A adsorption behavior on soil and biochar: impact of dissolved organic matter.

Dissolved organic matter (DOM) released from soil (SDOM) and biochar (BDOM) plays an important role in the fate of pollutants for the application of biochar in soil remediation. However, little attention has been paid to the impact of DOM on the adsorption of soil and/or biochar-bisphenol A (BPA) system. Hence, batch sorption experiments combined with quenching titration experiments were processed to reveal these behaviors and complexation mechanisms based on red soil and corn straw biochar. Moreover, multiple spectral technologies and methods were also introduced including ultraviolet-visible, three-dimensional excitation-emission matrix, synchronous fluorescence spectrum, two-dimensional correlation spectroscopy (2D-COS), and parallel factor analysis. Isothermal adsorption results showed that the non-linearity and the adsorption capacity both increased after the addition of biochar, indicating that biochar could improve the surface adsorption capacity of the sorption system. Besides, the sorption capacity of BPA decreased for soil while increased for biochar after removal of the water-extractable DOM. 2D-COS analysis showed that the protein-like components preferentially occurred for both SDOM and BDOM under BPA surrounding. In addition, C2 (humic-like), C4 (tyrosine-like), and C5 (tryptophan-like) in the two DOMs were all involved in the quenching reaction with BPA, with C4 and C5 having higher quenching degree than C2, suggesting that protein-like substances had stronger affinity quenching effect with BPA. This study highlighted the significance of fluorescence property for DOM, which can extend the knowledge of the fate of pollutants in the application of biochar.