Abstract

Low-cost mesoporous silicas of the SBA-15 family were prepared, aimed for removal of a broad spectrum of both cationic and anionic forms of hazardous metal pollutants (Cr(III, VI), Mn(II, VII), Pb(II), Cd(II), and Cu(II)) from environmental water. Series of mono-and bifunctional materials with immobilized ethylenediaminetriacetic acid (EDTA), primary amine (NH2), and quaternary ammonium (QAS) groups were prepared in a cost-efficient one-step synthesis using two silica sources, low-cost sodium metasilicate (Na2SiO3 9H(2)O) and the conventional source-tetraethylorthosilicate (TEOS). The functionalized SBA-15 samples obtained from both silica sources were highly ordered, as evidenced by TEM and SAXS data. All obtained materials were mesoporous with high surface area values of up to 745 m(2)/g, pore volumes from 0.99 to 1.44 cm(3)/g, and narrow pore distributions near 7 nm. The adsorption affinity of the EDTA-functionalized samples followed the common order Pb(II)> Cd(II)> Cu(II)> Cr(III)> Mn(II), which could be explained based on the Pearson theory. The highest adsorption capacities were observed for samples functionalized by EDTA groups using TEOS for synthesis (TEOS/EDTA): 195.6 mg/g for Pb(II), 111.2 mg/g for Cd(II), 58.7 mg/ g for Cu(II), 57.7 mg/g for Cr(III), and 49.4 mg/g for Mn(II). Moreover, organic matter (humic acid up to 10 mg/L) and inorganic (Na(I), K(I), Mg(II), Ca(II), etc) macrocomponents present in environmental water had almost negligible effect on the removal of these cations. The NaSi/EDTA/NH2 sample revealed a better selectivity compared to the NaSi/NH2 sample towards such species as Cr(III), Mn(II), Cd(II), and Cu(II). The chromate-ions uptake at pH 7.5 by the TEOS/QAS sample turned practically unaffected by the presence of doubly charged anions (CO32-, SO42-). The content of functional groups on the surface of MS decreased only slightly (similar to 1-5%) after several regeneration cycles. The complete desorption of all heavy metal ions can be achieved using 1 mol/L EDTA solution. Reusability tests demonstrated the complete stability of the adsorbent for at least five to six consecutive adsorption/ desorption cycles with no decrease in its adsorption characteristics compared to those obtained by 0.05 mol/L HNO3 treatments. The synthesized mesoporous materials were evaluated for removal of the heavy metal ions from drinking and different natural water samples, proving their potential as sustainable, effective, and cost-efficient adsorbents.

Published in

ACS Omega
2022, Volume: 7, number: 27, pages: 23576-23590
Publisher: AMER CHEMICAL SOC

SLU Authors

• Kessler, Vadim

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Seisenbaeva, Gulaim

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

Sustainable Development Goals

Ensure availability and sustainable management of water and sanitation for all


UKÄ Subject classification

Materials Chemistry
Water Treatment


Publication identifier

DOI: https://doi.org/10.1021/acsomega.2c02151

Permanent link to this page (URI)

https://res.slu.se/id/publ/118471