Adsorption of Endocrine Disrupting Chemicals and Phenanthrene by Biochars.

Biochars have been shown to improve the physical and chemical characteristics of soils. Their high capacity to sorb nutrients and chemicals may also reduce leaching of organic contaminants. In this study, two thermally and two hydrothermally manufactured biochars were examined to determine the relationships between their chemical characteristics and sorption behavior of two endocrine disrupting chemicals (bisphenol A, BPA and 17α-ethinyl estradiol, EE2) and one polycyclic aromatic hydrocarbon (phenanthrene, Phen). Combined data from NMR, FTIR and elemental analysis showed that the two types of biochars had different chemical compositions and structures; thermally made biochars had higher aromatic carbon contents, but lower H/C and O/C ratios than hydrothermal biochars. Sorption of BPA and EE2 by hydrothermal biochars was statistically higher than by the thermal ones. Comparable Phen sorption capacity and obvious difference in nonlinear coefficient n values for the two types of biochars indicate that partitioning interaction may be significant in Phen sorption by hydrothermal biochars while specific interaction (e.g., π-π electron donor-acceptor (EDA) complex) and pore-filling may be more important by thermal biochars. The results of this work suggest that in addition to improving soil quality, hydrothermal biochars may be used as a soil sorbent to adsorb relatively polar organic contaminants. This is an important finding because biochars may also have additional beneficial uses as a soil sorbent.