Highly efficient carbon quantum dot suspensions and membranes for sensitive/selective detection and adsorption/recovery of mercury ions from aqueous solutions

Chun Chieh Fu, Chien Te Hsieh*, Ruey Shin Juang, Jou Wen Yang, Siyong Gu, Yasser Ashraf Gandomi

*Corresponding author for this work

Research output: Contribution to journalJournal Article peer-review

40 Scopus citations

Abstract

Nitrogen-doped carbon quantum dots (CQDs), synthesized through a solid-phase microwave-assisted pyrolysis of citric acid and urea at 250 °C, were employed as highly-selective/-sensitive probe as well as an efficient adsorbent toward Hg 2+ ions that exist in aqueous solutions. The spherical CQDs possess a homogeneous dispersion with a narrow distribution, ranged from 2.5 to 5.5 nm. The fluorescence responses from CQD samples demonstrate triple band at ca. 450, 500 and 520 nm, influenced by the ratio of citric acid to urea in the carbon precursor. The fluorescence quenching ratio was found to be proportional to the Hg 2+ concentration within the solution. Such a correlation was formulated using Stern–Volmer model. The detection limit of CQDs toward Hg 2+ ions reached as high as 10 ppb, and the maximal adsorption capacity of Hg 2+ onto CQDs was as high as 3.33 g/g, which is 1280, 6, and 16 times higher than the values reported for the active carbon, graphene, and carbon nanotubes, respectively. The CQD-coated polymeric membrane also exhibits the fluorescence quenching and it is easily regenerated by iodide anions for subsequent usages. Accordingly, the functionalized CQDs pave the pathway for engineering the adsorption and recovery of toxic Hg 2+ contaminant that are present in aqueous solutions.

Original languageEnglish
Pages (from-to)127-136
Number of pages10
JournalJournal of the Taiwan Institute of Chemical Engineers
Volume100
DOIs
StatePublished - 07 2019

Bibliographical note

Publisher Copyright:
© 2019 Taiwan Institute of Chemical Engineers

Keywords

  • Adsorption capacity
  • Carbon quantum dots
  • Fluorescence quenching
  • Mercury ions
  • Solid-phase microwave-assisted method

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