You are here:
LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY
Citation:
Scheckel*, K G., J. A. Ryan, AND C A. Impellitteri**. LEAD SORPTION ON RUTHENIUM OXIDE: A MACROSCOPIC AND SPECTROSCOPIC STUDY. Schnoor, J. (ed.), ENVIRONMENTAL SCIENCE AND TECHNOLOGY. American Chemical Society, Washington, DC, 38(10):2836-2842, (2004).
Description:
The sorption and desorption of Pb on RuO2 xH2O were examined kinetically and thermodynamically via spectroscopic and macroscopic investigations. X-ray absorption spectroscopy (XAS) was employed to determine the sorption mechanism with regard to identity of nearest atomic neighbors, bond distances (R), and coordination numbers (N). The kinetics of the Pb-Ru-oxide sorption reaction are rapid with the equilibrium loading of Pb on the surface achieving approximately 1:1 wt/wt. XAS data indicate that Pb adsorbed as polynuclear bidentate inner-sphere Pb-Pb dimer complexes with first shell Pb-O parameters of RPb-O = 2.27 A and NPb-O = 2.1-2.5. Pb-Ru interatomic associations suggest two distinct surface coordinations of Pb to edges (RPb-RuI ~ 3.38 A and NPb-RuI ~ 1.0) and shared corners (RPb-RuII ~ 4.19 A and NPb-RuII ~ 0.8) on RuO2 octahedra (cassiterite-like structure) and due to the high sorption coverage of Pb, the formation of Pb-Pb dimers (RPb-Pb ~ 3.89 A and NPb-Pb ~ 0.9). Desorption studies as a function of aging time (1 hour to 1 year) using a continuous stirred-flow reactor with the background electrolyte (0.01 M NaNO3, pH 6) demonstrated that Pb was tightly bound (99.7 - 99.9% retained). The Pb sorption capacity and desorption retention on RuO2 xH2O is greater than that of other metal oxides examined in the literature. The results of this study may provide implication for use of RuO2 xH2O as a high capacity remediation treatment media.