Sorption Behavior of Phthalic Acid Esters on Reference Soils Evaluated by Soil Column Chromatography

Soils are commonly exposed to phthalic acid esters (PAEs) due to their wide usage in a large variety of fields. Several PAEs have been categorized as priority pollutants due to their environmental impact. Therefore, characterizing the sorption behavior of PAEs on soils is very important. Soil column chromatography was utilized to study sorption of dimethyl phthalate (DMP) and diethyl phthalate (DEP) on European and Chinese reference soils. The influence of different environmental conditions such as ionic strength, temperature and pH on the sorption process was investigated. Results show the organic carbon (OC) content in soil plays a main role in the sorption of DMP and DEP. Ionic strength and cation type influenced sorption of DMP and DEP on the two soils, however, in a different manner suggesting that OC in these two soils might be differently affected by the presence of ions. The sorption of DMP and DEP was also found to depend on the investigated pH range of mobile phase with significant relative changes of sorption coefficients in both soils. The influence of temperature on sorption to both soils was small and derived sorption enthalpies indicated that van der Waal's forces dominate the sorption of DMP and DEP, which leads us to propose that additional specific interactions such as hydrogen bonding only play a negligible role.