Selective removal of heavy metals by hydrotalcites as adsorbents in diverse wastewater: Different intercalated anions with different mechanisms

Ali Jawad, Li Peng, Zhuwei Liao, Zhihua Zhou, Ajmal Shahzad, Jerosha Ifthikar, Mengmeng Zhao, Zhulei Chen, Zhuqi Chen

Research output: Journal PublicationArticlepeer-review

82 Citations (Scopus)

Abstract

The designing of selective and efficient adsorbent for removal of heavy metals from wastewater of diverse chemistry is a challenging task for researchers. Herein, FeMgAl derived from layered double hydroxides (LDH) with different intercalated anions (CO3 2−, NO3−, S5 2− and MoS4 2−) as selective adsorbents were evaluated by considering capturing heavy metals from a complex aqueous environment such as: 1) adsorption of single metals ions from a mixture of Ag+, Hg2+, Pb2+, Cu2+, Cd2+, Co2+, Ni2+, Zn2+, 2) adsorption of heavy metals in the presence of huge amount of Ca2+, Mg+, Na+, Cl, NO3 and SO4 2− ions, 3) adsorption under different solution pHs, 4) solutions with high salinity etc. Out of the studied materials, fast kinetics, record capacities (582 for Hg2+ and 565 mg/g for Ag+) with enormous Kd values (1.0 × 108–2.5 × 107) placed FeMgAl–MoS4 (Fe–MoS4 LDH) as the most selective and promising material. FeMgAl–S5 (Fe–S5 LDH) was also impressive due to its good capacities (279 mg/g for Hg2+ and 341 mg/g for Ag+ ions) with Kd values (8.3 × 105–1.0 × 103). In contrast, FeMgAl–CO3 and FeMgAl–NO3 (Fe–CO3 LDH and Fe–NO3 LDH) showed very poor selectivity, lower capacities and very small Kd values. Furthermore, Fe–MoS4 LDH and Fe–S5 demonstrated negligible efficiency loss in the presence of competitive cations/anions or with change in solution pH. As confirmed by X-ray Diffraction (XRD) and Fourier Transformed Infrared (FTIR) analysis, a mechanism for adsorbed metals in the form of various coordinated complexes inside LDH layers was proposed for Fe–MoS4 or Fe–S5 LDHs. In contrast, a dominant precipitation mechanism as metal-hydroxide or metal-carbonate was suggested for Fe–CO3 and Fe–NO3 LDHs.

Original languageEnglish
Pages (from-to)1112-1126
Number of pages15
JournalJournal of Cleaner Production
Volume211
DOIs
Publication statusPublished - 20 Feb 2019
Externally publishedYes

Keywords

  • Adsorption
  • Heavy metal ions
  • Intercalated anions
  • Layered double hydroxide
  • Selectivity

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • General Environmental Science
  • Strategy and Management
  • Industrial and Manufacturing Engineering

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