Insights into the photo-induced formation of reactive intermediates from effluent organic matter: The role of chemical constituents

In the present study, the formation of triplet states of organic matters ((OM center dot)-O-3) from effluent organic matter (EfOM) under simulated solar irradiation was investigated. EfOM was separated into hydrophobic (HPO), transphilic (TPI), and hydrophilic (HPI) components. The quantum yield coefficients (f(TMP)) of (OM center dot)-O-3 were measured for each component and compared to those of reference natural organic matter (NOM). NaBH4 reduction was performed on the EfOM, and the effect of aromatic ketones moieties on triplet formation was also determined. Furthermore, the apparent quantum yield of O-1(2) (Phi(102)) and O-2(center dot-) (O-2(center dot-)) was measured. Our results suggested that the HPI fraction acted as a sink for (OM center dot)-O-3. A linear correlation was observed between f(TMP) and Phi(102) for NOM/EfOM, except for NaBH4-reduced effluent and HPI components. Both f(TMP) and Phi(102) were positively correlated with the contribution rates of NaBH4-reducible moieties (aromatic ketones) toward (OM center dot)-O-3. Aromatic ketones were primarily responsible for the production of (OM center dot)-O-3 from EfOM, whereas quinone moieties played a key role in the production of (OM center dot)-O-3 in NOM-enriched solutions. Understanding the role of chemical constituents on the photo activity of EfOM/NOM is essential for providing useful insights on their photochemical effects in aquatic systems. (C) 2017 Elsevier Ltd. All rights reserved.