Mercury reduction and chemisorption on the surface of synthetic zeolite silver nanocomposites: equilibrium studies and mechanisms

Z. Tauanov, J. Lee, V. J. Inglezakis

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

This work presents the utilization of a coal power plants waste, namely coal fly ash for the synthesis of zeolites and zeolite silver nanocomposites for the removal of Hg2+ from water. Equilibrium data are derived for all materials for mercury concentration range of 10–500 mg/L and models are applied. The removal mechanisms are discussed in detail and complemented by XRD, XRF, SEM-EDS, and TEM characterizations and water phase mercury speciation modeling. According to findings, the adsorption capacity of zeolites is about 4 mg/g and increased by almost 5 times after the modification with silver nanoparticles to 20.5–22.3 mg/g. Langmuir equilibrium model fits well the experimental data of the nanocomposites indicating monolayer adsorption process. The mechanism is complex, involving Hg2+ reduction to Hg+ and possibly Hg0 followed by formation of calomel and amalgams on the surface of the nanocomposites. The mercury reduction is accompanied by Ag0 oxidation to Ag+ and subsequent formation of silver chloride.

Original languageEnglish
Article number112825
JournalJournal of Molecular Liquids
Volume305
Early online date2 Mar 2020
DOIs
Publication statusPublished - 1 May 2020

Keywords

  • adsorption isotherms
  • mercury removal
  • nanocomposites
  • silver
  • zeolites

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