Browsing by Author "Cong, Lili"
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Item A rapid, simple method to measure the desorption-resistant fraction of sediment sorbed contaminants(2003) Cong, Lili; Tomson, Mason B.Resistant desorption has been widely observed for hydrophobic organic contaminants. It is an important process that impacts sediment quality and contaminated sediment management. Conventional approaches to measure the desorption resistant fraction of sorbed contaminants are by conducting repetitive water desorption, in which the desorption resistant fraction is determined by measuring the solid phase concentration after extended desorption times. This method is time-consuming and impractical for widespread applications. In addition, the final measurement of the solid phase concentration is subject to considerable error, because there is always a fraction of water associated with the solid due to the incomplete separation of the liquid phase from the solid. In this research, a new experimental protocol was developed to rapidly and accurately measure the desorption resistant fraction based on the study of desorption of phenanthrene from Utica sediment.Item Sorption/desorption of arsenic to nanometer scale magnetite(2005) Cong, Lili; Tomson, Mason B.The interaction of arsenite (As(III)) and arsenate (As(V)) with magnetite nanoparticles has been studied to evaluate the environmental impact of magnetite nanoparticles and possible beneficial use of these nanoparticles in water treatment. The effects of particle size (20--300 nm) and pH on the sorption/desorption of AS(III) and As(V) on magnetite nanoparticles were examined. On a surface area basis, it was found that large and nanometer scale magnetite particles had similar maximum As(III)/As(V) sorption capacities. However, the sorption of As(III) to magnetite showed the same Langmuir sorption slope for the nanometer scale particles as for the large particles, while the sorption of As(V) to magnetite showed a larger Langmuir sorption slope for the nanometer scale particles than for the large crystals. The particle size effect on sorption is constant over a pH range of 4.8 to 8. Sorption of As(V) was found to be greater at lower pH, while sorption of As(III) was not pH sensitive. The sorption data of both As(III) and As(V) have been modeled with the Diffuse Double Layer model. Stronger desorption hysteresis was observed for both As(III) and As(V) sorption to nanometer scale magnetite particles than that to large magnetite particles, which indicates that the decrease of particle size may increase the affinity of sorption. The experimental results showed that magnetite nanoparticles are potentially a very effective sorbent for arsenic removal in water treatment.