Monitoring Soil Column Mobility of Cross-Linked and Soluble Polyacrylates Using Gel Permeation Chromatography

The potential fate of polymeric materials in soils is important to environmental safety. This study validated highperformance gel permeation chromatography (HPGPC) to assess elution behavior of a commercially available, crosslinked, high molecular weight polyacrylate absorbent (PA) and a soluble low molecular mass (4500 Da), linear poly(acrylic acid) (LPA) in three types of columns prepared from sandy and loamy soils. HPGPC was used to monitor the elution of the soluble PA and LPA from the columns. The LPA represents the fraction (<4%) of the PA that is typically extractable in commercial PA material. Over 99% of the PA sample was found to be retained on a Borden sand test column. The amount that moved is probably related to the extractable polymer. A total of 92% of the non-cross-linked LPA was retained on a Borden sand column. Virtually all of the LPA was retained on the Fox loam column. PA mobility could not be studied bn the Fox loam soil; however, the high clay content of this soil is expected to make the PA less mobile than in Borden sand. Londo loam soil yielded high levels of background interferents for PA and LPA, preventing acquisition of definitive mobility data. However, LPA and PA are expected to be less mobile on Londo loam than on Borden sand due to the higher organic matter/clay contents. These results indicate that typical consumer product-grade PAs would not move appreciably through common soil types in or near landfills. The results also support the use of LPA as a model for studying movement of the soluble portion of commercially available PA through soils and demonstrate that HPGPC is suitable for quantifying soluble polyacrylates in synthetic groundwater effluents.