Synthesis of Gold Nanoparticles-Aluminium Oxide Adsorbents for Analysis of Mercury Species
Date Issued
2011
Date
2011
Author(s)
Lo, Sut-I
Abstract
We report a new and effective adsorbent for removal of metal ions and mercury species. By mixing Au NPs (13 nm in diameter) with aluminum oxide particles (50-200 μm in diameter), Au NPs─Al2O3 adsorbents are easily prepared. Three adsorbents—Al2O3, Au NPs, and Au NPs─Al2O3—have been tested for removal of the metal ions (Cd2+, Co2+, Cr3+, Ni2+, Pb2+) and mercury species [Hg2+, methylmercury (CH3Hg+), ethylmercury (C2H5Hg+), and phenylmercury (C6H5Hg+)]. The Au NPs adsorbent has higher binding affinity toward Hg2+ ions (Kd = 0.3 nM; Bmax = 3370 μmol/g Au NP) than that of Al2O3 adsorbent (Kd = 52.9 nM; Bmax = 130 μmol/g Al2O3). Relative to the individual Al2O3 and Au NPs adsorbents, the Au NPs─Al2O3 adsorbents have higher affinity for mercury species (CH3Hg+: Kd = 6.9 nM; C2H5Hg+: Kd = 6.2 nM; C6H5Hg+: Kd = 7.9 nM; Hg+: Kd = 19.2 nM) and other tested metal ions (Cd2+: Kd = 5.5 nM; Co2+: Kd = 8.1 nM; Cr3+: Kd = 40.5 nM; Ni2+: Kd = 16.9 nM; Pb2+: Kd = 4.6 nM), respectively. The Au NPs─Al2O3 adsorbents provide a synergic effect and thus are effective for removal of most tested metal ions and organic mercury species. After preconcentration of mercury ions by Au NPs─Al2O3 adsorbent, inductively coupled plasma-mass spectrometry (ICP-MS) allows the detection of mercury ions down to sub-fM level in aqueous solution. The Au NPs─Al2O3 adsorbent allows effective removal of mercury species spiked in nature waters (lake water, ground water and sea water), with the efficiencies greater than 97%. We have used sequentially Al2O3 and Au NPs─Al2O3 adsorbents for selective removal of Hg2+ and CH3Hg+ ions from a certified fish sample (DORM-2). The ICP-MS has been applied to determine the concentrations of the preconcentrated Hg2+ and CH3Hg+ ions, with results that are in good agreement with the certified values. The low-cost, effective, and stable Au NPs─Al2O3 adsorbents show great potential for economic use in removal of metal ions and various mercury species.
Subjects
mercury
methylmercury
gold nanoparticles
aluminium oxide
Type
thesis
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