Efficient, stable and selective adsorption of heavy metals by thio-functionalized layered double hydroxide in diverse types of water

Jawad Ali, Huabin Wang, Jerosha Ifthikar, Aimal Khan, Ting Wang, Kun Zhan, Ajmal Shahzad, Zhulei Chen, Zhuqi Chen

Research output: Journal PublicationArticlepeer-review

130 Citations (Scopus)

Abstract

The designing of efficient, selective and stable adsorbents for heavy metals removal remained a challenging task, as most adsorbents did not exhibit consistent performance in diverse types of water. Unlike traditional adsorbents based on surface oxygen groups, thio-functionalized layered double hydroxide (LDH) as Mn-MoS4 was designed by inserting MoS42− anions into lamellar layers in LDH, and was applied as a highly stable, efficient and selective adsorbent for heavy metals removal. The record high distribution coefficient (Kd ∼ 107–108 mL/g), fast kinetics and enormous saturated uptake capacities (594, 564 & 357 mg/g) for Hg2+, Ag+ and Pb2+ placed Mn-MoS4 as the most efficient adsorbent for the removal of such metals so far. Further, Mn-MoS4 can completely tolerate the impact of huge concentration of background electrolytes (Ca2+, Mg2+, Na+, Cl, NO3 & SO42−), and effectively control the concentrations of Hg2+, Ag+ and Pb2+ ions from tap water, lake water or industrial wastewater far below the limitation in drinking water. Similarly, Mn-MoS4 is a potential filter due to its consistent performance over a broad pH range (from 2.0 to 11.0), changing ionic strength (up to 100 mM) or in the presence of organic matters. These remarkable features originate from the dominant chemical adsorption mechanism through inner-sphere coordination between thio groups as soft Lewis acid and Hg2+, Ag+ and Pb2+ as soft Lewis bases. More interestingly, LDH layers offer protective space for intercalated MoS42− anions against oxidation, and facilitate Mn-MoS4 with the advantage of easy storage and application over other adsorbents.

Original languageEnglish
Pages (from-to)387-397
Number of pages11
JournalChemical Engineering Journal
Volume332
DOIs
Publication statusPublished - 15 Jan 2018
Externally publishedYes

Keywords

  • Adsorption
  • Heavy metal ions
  • Layered double hydroxide
  • Selectivity
  • Thiol

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering

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