Water solubility enhancement of pyrene in the presence of humic substances

The apparent water solubility of pyrene (pyr) was enhanced in the presence of the humic substances (HSs). To quantitatively treat the water solubility enhancement of pyr, the partition coefficients of pyr, Kdoc, were evaluated by considering the partition of pyr from water into HS. The log Kdoc values increased with the increase of the parameters of aromaticity for the HSs (the absorptivity at 280nm and the content of aromatic protons measured by 1H-NMR). These results showed that the degree of aromaticity for the HSs was greatly related to the water solubility enhancement of pyr.