Interaction of polar and nonpolar organic pollutants with soil organic matter: Sorption experiments and XXXX simulation.

@entity15213 @entity4880 @entity74 @entity12683 @entity10040
UNASSIGNED: The fate of organic pollutants in the environment is influenced by several factors including the type and strength of their interactions with soil components especially SOM. However, a molecular level answer to the question "How organic pollutants interact with SOM?" is still lacking. In order to explore mechanisms of this interaction, we have developed a new SOM model and carried out @entity74 ( @entity74 ) simulations in parallel with sorption experiments. The new SOM model comprises free SOM functional groups ( @entity4880 and @entity12683 ) as well as SOM cavities (with two different sizes), simulating the soil voids, containing the same SOM functional groups. To examine the effect of the hydrophobicity on the interaction, the organic pollutants @entity15213 ( @entity15213 , non-polar) and @entity10040 (SAA, polar) were considered. The experimental and theoretical investigations explored four major points regarding sorption of SAA and @entity15213 on soil, yielding the following results. 1-The interaction depends on the SOM chemical composition more than the SOM content. 2-The interaction causes a site-specific adsorption on the soil surfaces. 3-Sorption hysteresis occurs, which can be explained by inclusion of these pollutants inside soil voids. 4-The hydrophobic @entity15213 is adsorbed on soil stronger than the hydrophilic SAA. Moreover, the theoretical results showed that @entity15213 forms stable complexes with all SOM models in the aqueous solution, while most of SAA-SOM complexes are accompanied by dissociation into SAA and the free SOM models. The SOM-cavity modeling had a significant effect on binding of organic pollutants to SOM. Both @entity15213 and SAA bind to the SOM models in the order of models with a small cavity>a large cavity>no cavity. Although @entity15213 binds to all SOM models stronger than SAA, the latter is more affected by the presence of the cavity. Finally, @entity15213 and SAA bind to the hydrophobic functional group ( @entity12683 ) stronger than to the hydrophilic one ( @entity4880 ) for all SOM models containing a cavity. For models without a cavity, SAA binds to @entity4880 stronger than to @entity12683 .
