1 / 15

A rsenic Speciation Based on Molecular Weight : Equilibrium D ialysis

A rsenic Speciation Based on Molecular Weight : Equilibrium D ialysis. Sheena Powell Szuri, BS Florida International University TAG Meeting January 10, 2003. Purpose of Study. Arsenic (As) leaching from CCA structures is a problem

johniedwards
Download Presentation

A rsenic Speciation Based on Molecular Weight : Equilibrium D ialysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Arsenic Speciation Based on Molecular Weight:Equilibrium Dialysis Sheena Powell Szuri, BS Florida International University TAG Meeting January 10, 2003

  2. Purpose of Study • Arsenic (As) leaching from CCA structures is a problem • As can form complexes with compounds of different molecular weight (an indication of particle size) • Dissolved organic matter (DOM), Fe, Mn, Ca, Al • Size of complexes of As affect bioavailability & mobility through soil Photo: Ken Helle for the St. Petersburg Times

  3. Method Development • Equilibrium Dialysis • Facile separation of compounds based on molecular weight/size • Inductively-Coupled Plasma Mass Spectrometry (ICP/MS) • Hydride-Generation Atomic Fluorescence Spectroscopy (HG/AFS)

  4. Equilibrium Dialysis

  5. The Dialysis Membranes • Material: • cellulose ester • polyvinylidene fluoride (PVDF) • nitrocellulose • Wet or Dry • Treatment • Clamps • Pore Size • 0.5kD • 3.5kD • 12kD

  6. Experimental Design

  7. Control Study Determine best equilibrium time for 3 membrane sizes (0.5kD, 3.5kD, 12kD) As As As W + As W + As W Time 1 Time 2 Time 3 Equilibrium

  8. Arsenic Concentration0.5kD Equilibrium>3 days Inside Outside

  9. Arsenic Concentration 3.5 kD Inside Outside Equilibrium<1 day

  10. Arsenic Concentration 12kD Inside Outside Equilibrium<1 day

  11. Leachate Study • Determine concentration of As in different molecular weight fractions • Sample collection • A Construction and Demolition (C&D) landfill • A Municipal Solid Waste (MSW) landfill L L KCl + L KCl

  12. C&D Leachate ICP-MS HG-AFS I I I O I O O O I O O I

  13. MSW Leachate ICP-MS HG-AFS O O O I O I I O I O I I

  14. Conclusions • Equilibrium dialysis - fast, simple, effective • As bound to molecules less than 3.5kD (also less than 12kD) • Future studies: • Acquire additional leachate samples • Examine influence of matrix elements (DOM, Fe, Mn, Ca, Al) • Examine influence of physicochemical parameters (pH, Eh, salinity) • Need to investigate leachates with 0.5kD membrane

  15. Questions? Sheena Powell Szuri, BS Florida International University TAG Meeting January 10, 2003

More Related