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Polyethylenimine modified potassium tungsten oxide adsorbent for highly efficient Ag + removal and valuable Ag 0 recovery.
- Source :
-
The Science of the total environment [Sci Total Environ] 2019 Nov 20; Vol. 692, pp. 1048-1056. Date of Electronic Publication: 2019 Jul 21. - Publication Year :
- 2019
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Abstract
- Elemental Ag <superscript>0</superscript> is well known for its remarkable catalytic and antibacterial properties, thus the regeneration of valuable Ag <superscript>0</superscript> metal from Ag <superscript>+</superscript> wastewater is of great significance. In this study, a novel polyethylenimine (PEI) modified potassium tungsten oxide (N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> ) adsorbent was prepared for Ag <superscript>+</superscript> removal and reduction to Ag <superscript>0</superscript> using glutaraldehyde as crosslinking agent. XPS and FT-IR spectra verified PEI successfully anchored on the surface O and W atoms of K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> through aldehyde bridges. The content of PEI in N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> was calculated as 8.74wt% by TG curve. A heterogeneous PEI coating was observed in the SEM and TEM images. The N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> exhibited larger Ag <superscript>+</superscript> uptake (48.25mg/g) than the raw K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> (42.50mg/g) though required a longer equilibrium time. This was due to the combined results of strong chelation and weak electrostatic repulsion that meanwhile occurring on the positive-charged surface of N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> . The maximum Ag <superscript>+</superscript> uptake on N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> was 72.5mg/g, which was larger than many of the reported adsorbents. Furthermore, the prepared N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> displayed good anti-interference toward background ions (Na <superscript>+</superscript> , K <superscript>+</superscript> ) and hold a stable Ag <superscript>+</superscript> removal (>95%) after five runs of recycling tests. The mechanism studies elucidated that NH/N groups from the PEI modified N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> mainly accounted for the Ag <superscript>+</superscript> adsorption and Ag <superscript>0</superscript> recovery in the adsorption-reduction process. Ion-exchange between Ag <superscript>+</superscript> and K <superscript>+</superscript> from the N-K <subscript>2</subscript> W <subscript>4</subscript> O <subscript>13</subscript> lattice also occurred. This work provided a facile method to synthesize a promising adsorbent for Ag <superscript>+</superscript> wastewater remediation and valuable Ag <superscript>0</superscript> recovery.<br /> (Copyright © 2019. Published by Elsevier B.V.)
Details
- Language :
- English
- ISSN :
- 1879-1026
- Volume :
- 692
- Database :
- MEDLINE
- Journal :
- The Science of the total environment
- Publication Type :
- Academic Journal
- Accession number :
- 31539937
- Full Text :
- https://doi.org/10.1016/j.scitotenv.2019.07.328