Highly selective and efficient heavy metal capture with polysulfide intercalated layered double hydroxides

Shulan Ma, Qingmei Chen, Hao Li, Pengli Wang, Saiful M. Islam, Qingyang Gu, Xiaojing Yang, Mercouri G. Kanatzidis

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Abstract

Polysulfide [Sx]2- (x = 2, 4) species were intercalated into magnesium-aluminium layered double hydroxide (MgAl-LDH) by a [Sx]2-/NO3- anion-exchange reaction. The resulting Sx-LDH materials exhibit excellent affinity and selectivity for heavy metal ions such as Cu2+, Ag+ and Hg2+. For the highly toxic Hg2+, the distribution coefficient Kd values can reach ∼107 mL g -1. The Sx-LDH materials rapidly reduce the concentrations of Hg2+ and Ag+ ions in testing solutions from ppm levels to trace levels of ≤1 ppb. A larger series of metal ions were investigated and the selectivity order of Ni2+, Co2+ ≪ Zn 2+, Pb2+ < Cd2+ < Cu2+, Ag+, Hg2+ was observed. The Sx-LDH materials show higher selectivity for Cu2+/Zn2 compared to Co 2+/Ni2+, providing good separation for these transition metal ions. After ion capture, the LDH hybrid materials retained the original hexagonal prismatic shape and showed good stability under acidic conditions (pH ∼ 3). The adsorption process of the metals occurs via M-S bonding. The enhanced environmental stability of the [Sx]2- groups provided by the LDH protective space, the confinement effect offered by the LDH layers, along with the easy accessibility of polysulfide ions to metal ions enable high capture ability and excellent selectivity. The Sx-LDH materials are thus promising as superior sorbents for the decontamination of polluted water. 2014 This journal is

Original languageEnglish
Pages (from-to)10280-10289
Number of pages10
JournalJournal of Materials Chemistry A
Volume2
Issue number26
DOIs
Publication statusPublished - Jul 14 2014

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ASJC Scopus subject areas

  • Chemistry(all)
  • Renewable Energy, Sustainability and the Environment
  • Materials Science(all)

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