GOALI: Adsorption Competition in Soils and Sediments

0089903 Axe The objectives of this award are to understand the effect of competing ions on contaminant adsorption in model systems, develop mechanistic models for their interactions with mineral surfaces, determine transport and thermodynamic parameters to describe their behavior and test the ability of resulting models to predict their behavior in soils and sediments. Although a number of researchers have studied the adsorption of heavy metals on goethite and other hydrous oxides, only a limited number of studies have dealt with heavy metal adsorption competition on hydrous oxides macroscopically. In contaminated systems, the presence of multiple contaminants is more frequent than the existence of only one contaminant; heavy metals and dissolved minerals, along with plant nutrients, exist in the subsurface environment. Using molecular-scale and macroscopic sorption data, the overall goal of this collaborative research activity is to develop surface complexation models that can be applied and integrated into fate and transport models for predicting speciation and mobility of toxic trace metal ions in groundwater, soils and sediments when competing ions are present. The heavy metals will include those most freequently found at Superfund and DOD sites, i.e., Ni, Pb and Zn. By using macroscopic and spectroscopic measurements to evaluate the adsorption mechanisms, the types of sites of the goethite surface will be probed along with the adsorption capacity and competition for the different types of sites. Mechanistic, microscopic models of metal interactions will be developed including competition at the goethite surface. These models, along with tranport and thermodynmic parameters determined through the proposed collaborative research, will provide the ability to accurately model contaminant mobility and bioavailability. Results of this work will be applied in actual treatment and remediation problems at DuPont; this will serve as a useful calibration mechanism for validating the relevance of the fundamental research and for designing future experiments. This research project is awarded under the NSF GOALI (Grant Opportunities for Academic Liaison with Industry) program and represents a collaborative effort with researchers from DuPont, which is providing support for one of the two graduate students supported by this grant. ***