Aqueous and vapor phase mercury sorption by inorganic oxide materials functionalized with thiols and poly-thiols

A. Makkuni, L. G. Bachas, R. S. Varma, S. K. Sikdar, D. Bhattacharyya

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

The objective of the study is the development of sorbents where the sorption sites are highly accessible for the capture of mercury from aqueous and vapor streams. Only a small fraction of the equilibrium capacity is utilized for a sorbent in applications involving short residence times (e.g., vapor phase capture of mercury from coal-fired power plant flue gases). So, dynamic capacity rather than equilibrium capacity is more relevant for these kinds of situations. Rapid sorption rates and higher dynamic capacity can be achieved by increasing the accessibility of active sites and decreasing the diffusional resistance to mass transport for the adsorbing species. This requires the use of open structured sorbent materials and attachment of functional groups on the external surface area of supports. The strong interaction of sulfur containing ligands (e.g., thiol) with mercury makes them suitable candidates for immobilization on these types of materials. In this study, inorganic oxide supports like alumina and silica are functionalized with thiol moieties like mercapto silane, cysteine and poly-cysteine for capturing mercury from aqueous and vapor phase. Aqueous phase Hg (II) sorption studies with cysteine/poly-cysteine functionalized silica showed that high dynamic capacity can be achieved by attaching active sites (thiol) on the external area of supports. Vapor phase Hg capture studies with thiol-functionalized mesoporous silica (Hg0 concentration = 3.37mg/m3N2 as the carrier, gas temperature = 70°C) yielded a capacity of 143 μg Hg/g for the sorbent. Although the sulfur content for the sorbent was low (0.80wt.%) the molar ratio of Hg captured to sulfur was comparatively high (2.86×10-3) pointing to the high accessibility of sulfur sites.

Original languageEnglish (US)
Pages (from-to)87-96
Number of pages10
JournalClean Technologies and Environmental Policy
Volume7
Issue number2
DOIs
StatePublished - May 1 2005
Externally publishedYes

Keywords

  • Alumina
  • Diffusion
  • Dynamic capacity
  • Ligands
  • Pollution control
  • Power plant
  • Silica

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Management, Monitoring, Policy and Law

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