Acid mine drainage (AMD) from metal sulfides that result in heavy metal leaching into the environment is a prevalent problem. Coating natural pyrite (FeS2/SiO2) and galena (PbS) mineral surfaces with benzene-1,3-diamidoethanethiol (BDET) was found to be an effective method for preventing heavy metal leaching into aqueous media. The natural pyrite examined was found to have a significant amount of quartz in its matrix that influenced its ability to bind with BDET. X-ray photoelectron spectroscopy (XPS) core level shifts of the S 2p, N1s, Fe 2p and Pb 4f orbitals upon complexation revealed that greater BDET binding to these metal sulfides correlated with ligand-to-metal (LMCT) charge transfer. Improved binding of BDET to FeS2 over PbS was observed as the concentration of metal in the supernatant dramatically decreased. Stronger BDET binding to FeS2/SiO2 was attributed to LMCT from the open shell Fe absent in the corresponding metal in galena (Pb), which had a closed shell configuration. Comparison of N 1s spectra in control experiments show that SiO2 resulted in a reduced number of N 1s oxidation states, improving anti-leaching properties. Coverage of BDET complexed to FeS2/SiO2 was markedly greater than that for PbS, in agreement with inductive coupled plasma optical emission spectrometry (ICP-OES) data. Photoelectron spectroscopy data revealed that the electronic shell structure of the sulfide metal is a contributing factor in BDET's ability to inhibit heavy metal leaching.
|Number of pages||7|
|Journal||Colloids and Surfaces A: Physicochemical and Engineering Aspects|
|State||Published - Dec 31 2008|
Bibliographical noteFunding Information:
We gratefully acknowledge partial support of this work by the Foundation for Chemical Research, Inc. and the University of Missouri Research Board. We thank Mr. Sean Mickey for assistance in the BET surface area measurements.
- Acid mine drainage
- Fe 2p orbital
- Mineral sulfides
- Pf 4f orbital
- Thiolate coating
- X-ray photoelectron spectroscopy
ASJC Scopus subject areas
- Surfaces and Interfaces
- Physical and Theoretical Chemistry
- Colloid and Surface Chemistry