Influence Of Mirco-particles In Groundwater On Adsorption And Facilitated Transport Of Phthalate Esters

Phthalate esters (PAEs) are commonly detected in environment because of its widely use. Their toxic is mainly reflected in its role as an environmental hormone. Generally, PAEs can be detected in water, sediment and soil, and air. The study for the migration of PAEs is necessary. On the other hand, some organic pollutants which are hydrophobic or hardly soluble in water in theroy can be detected in groudwater. Former researchers reported that this is"Colloid-facilitated Transport", these indissolved PAEs can be moved into ground water by colloidal particles and then migrated in the aquifer.This paper focused on the possibility and potential of facilitated transport of PAEs, by analyzing the distribution of PAEs in micro-particles and water. In this study, some PAEs (DMP DEP BBP & DOP) were selected as the target contaminants, and two standard soils (GSS-2 & GSD-9) were used as the sources of micro-particles in water. Samples were filtrated and separated at different micro-particle sizes (10, 2, 0.45 and 0.1μm), and PAEs was analyzed. The particles which sizes were greater than 10μm and 0.45-5.0μm were detected by IR and XPS, in order to known the influence of physical and chemical character of particles on the distribution.The results indicated that DMP & DEP tend to distribute in solution but DOP prefered to in the particles (size>10μm) when the GSS-2 particles were in the solution system. BBP was stongly adsorped by the particles (size< 2.0μm). For GSD-9 particles in the solution system, DMP DEP & DOP have the same distribution as GSS-2, and BBP was also present in the particles which size>10μm. This phenomenon seems to be related to Kow of PAEs. BBP & DOP have larger Kow, and distribute in the particle. DMP & DEP have low Kow and distribute in the water phase. However, the results can not simply compared the difference of distributions of PAEs, especially BBP, because the reproducibility of the GSS-2 and GSD-9 results was not well.The particles characterization results showed that the total amount of aromatic functional groups in GSD-9 particles and GSS-2 particles are different. The smaller GSD-9 particles might have low priority to adsorpt organic pollutants due to the organic carbon content and polar. In the GSD-9 experimental, the data that BBP mainly concentrated in the particles which size>10μm may be related to the character of GSD-9 smaller particles. Different sizes of GSS-2 particles did not have a difference in surface properties of organic carbon; that may affect the BBP in the distribution.Base on these results, it could be found that the adsorption of PAEs may be affected by its properties and particles characterization, and DOP and BBP is the most likely occurred facilitated transport.