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Leaching Of Metals And Metalloids From Highway Marking Glass Beads And The Potential Environmental Impact, Nimrat K. Sandhu
Leaching Of Metals And Metalloids From Highway Marking Glass Beads And The Potential Environmental Impact, Nimrat K. Sandhu
Dissertations
Glass beads are embedded in pavement markings to obtain retroreflectivity which plays a crucial role in the lighting-up effect needed for safe driving. Elevated metal and metalloid concentrations of As, Sb, and Pb have recently been observed in imported glass beads. The main objective of this research was to assess the environmental impact associated with applying these imported glass beads in highway markings. To achieve this objective, total metal concentrations were measured using two techniques: hydrofluoric acid digestion followed by inductively coupled plasma mass spectroscopy (HF/ICP-MS), and field portable x-ray fluorescence (FP-XRF) spectroscopy. A number of leaching studies were conducted …
Phosphate And Thermal Stabilization Of Heavy Metals In Dredged Sediments, Peter Kuria Ndiba
Phosphate And Thermal Stabilization Of Heavy Metals In Dredged Sediments, Peter Kuria Ndiba
Dissertations
Treatment and reuse of dredged harbor sediments in construction as an alternative to disposal reduces costs and conserves resources. This research focused on leachability of metal contaminants subsequent to phosphate addition and thermal treatment at 700 °C. X- ray absorption spectroscopy (XAS) in combination with principal component analysis, target transformation, and linear combination revealed that in the untreated sediments Zn precipitated as the relatively soluble smithsonite (ZnCO3) (67%) and adsorbed to hydrous iron oxides (15%) and hydrous manganese oxides (18%). Phosphate addition and calcination resulted in sparingly soluble phases, hopeite (Zn3(PO4)2.4H2 …