Physical and chemical formations of lead contaminants in clay and sediment

N. M. Nagy, J. Kónya, M. Beszeda, I. Beszeda, E. Kálmán, Zs Keresztes, K. Papp, I. Cserny

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

A possible sink for divalent lead in the environment is clays such as montmorillonite that have cation exchange capacities. To assess the reaction, a calcium-montmorillonite was mixed with lead perchlorate solutions of varying concentrations and at various pH's. The recovered solids were studied by a variety of techniques (X-ray photoelectron and infrared spectroscopy, scanning electron microscopy, and atomic force microscopy) to determine what, if any, alterations occurred. The ion exchange of lead for calcium reduced the hydrated water in the clay, and evidence for proton-lead ion exchange at the edges of the sheets was observed. Evidence for a second, unexpected, reaction was also observed. Small spots (0.2 to 1 μm) of lead enrichment were observed on the surface of clay particles. They were also observed on clays recovered from the sediment of a Hungarian lake. The results show that lead ions are adsorbed onto montmorillonite by two processes: cation exchange and nano- and microparticle production. Cation exchange leads to the even distribution of the ions, while the production of spots causes the enrichment of lead ions. The production of these particles is not expected from the thermodynamic properties of the solution and cannot be observed in the absence of clay.

Original languageEnglish
Pages (from-to)13-22
Number of pages10
JournalJournal of colloid and interface science
Volume263
Issue number1
DOIs
Publication statusPublished - Jul 1 2003

Keywords

  • Atomic force microscopy
  • Calcium-montmorillonite
  • Infrared spectroscopy
  • Lead-montmorillonite
  • Microparticles
  • Nanoparticles
  • Radioisotopic labeling
  • Scanning electron microscopy
  • X-ray photoelectron spectroscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Surfaces, Coatings and Films
  • Colloid and Surface Chemistry

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