Radical chemistry of dissolved black carbon under sunlight irradiation: quantum yield prediction and effects on sulfadiazine photodegradation

Dissolved black carbon (DBC) is regarded as an important part of the natural organic matter pool. However, it is unclear about DBC's photochemical activity and the relationships between reactive intermediates (RIs) and the molecular structure of DBC remain unclear. In this study, we investigate the photochemical formation ability of RIs and spectral parameters (E-2/E-3, S275-295) of DBC made from five types of plants at five pyrolysis temperatures. The results showed that there were good linear regressions between the RI quantum yields and the spectral parameters (E-2/E-3, S275-295), and this was indicative of the RI generation prediction from DBC under solar irradiation. The DBC-mediated photochemical experiment of sulfadiazine revealed that (DBC)-D-3* was the primary active species for the indirect photodegradation of sulfadiazine. Further studies indicated that a linear relationship was observed between the indirect photodegradation ability of sulfadiazine induced directly by (DBC)-D-3* at different pyrolysis temperatures and the (DBC)-D-3* quantum yields or E-2/E-3. These findings indicate that the simple models of the RI quantum yield as a function of spectral parameters can be used to evaluate the degradation of pollutants with known DBC spectral parameters.

Automated summary

The study found a linear relationship between spectral parameters and reactive intermediate quantum yields, allowing for the prediction of RI generation from DBC under solar irradiation. Experimentation with DBC showed that DBC-D-3* was the primary active species for the indirect photodegradation of sulfadiazine. Further research revealed a linear relationship between the indirect photodegradation ability of sulfadiazine induced by DBC-D-3* at different temperatures and the DBC-D-3* quantum yields or E-2/E-3.