Limits...
Enhanced adsorption of trivalent arsenic from water by functionalized diatom silica shells.

Zhang J, Ding T, Zhang Z, Xu L, Zhang C - PLoS ONE (2015)

Bottom Line: The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume.X-ray photoelectron spectroscopy (XPS) further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III) and thiol groups, and through the surface complexation between As(III) and protonated nitrogen and hydroxyl groups.Results indicate that this functionalized bioadsorbent with a high As(III) adsorption capacity holds promise for the treatment of As(III) containing wastewater.

View Article: PubMed Central - PubMed

Affiliation: Environmental Science Institute, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang, People's Republic of China.

ABSTRACT
The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino) groups to effectively remove arsenic in its toxic As(III) form (arsenite) predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III) concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III) at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III) adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film) and internal (intraparticle) diffusion can be rate-determining for As(III) adsorption. Fourier transform infrared spectroscopy (FTIR) indicated that the thiol and amino groups potentially responsible for As(III) adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS) further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III) and thiol groups, and through the surface complexation between As(III) and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III) adsorption capacity holds promise for the treatment of As(III) containing wastewater.

No MeSH data available.


Related in: MedlinePlus

X ray diffraction (XRD) patterns of the raw adsorbent (curve a) and the modified adsorbent (curve b).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4383452&req=5

pone.0123395.g001: X ray diffraction (XRD) patterns of the raw adsorbent (curve a) and the modified adsorbent (curve b).

Mentions: The raw and functionalized diatom frustules were subjected to XRD analysis to elucidate the chemical nature of the modification. Contrary to the amorphous raw diatom frustules (curve a in Fig 1), the XRD spectrum for functionalized diatom frustules showed two distinct peaks characteristic of the crystalline presence at 2θ of 7.5 and 21.2°, corresponding to a d-spacing of 11.78 and 4.26 Å, respectively. The peak at 21.2° is attributed to the presence of quartz as previous studies have reported [11,12], whereas the peak at 7.5° can be assigned to the silanizing agent that became incorporated into the modified diatom frustules.


Enhanced adsorption of trivalent arsenic from water by functionalized diatom silica shells.

Zhang J, Ding T, Zhang Z, Xu L, Zhang C - PLoS ONE (2015)

X ray diffraction (XRD) patterns of the raw adsorbent (curve a) and the modified adsorbent (curve b).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4383452&req=5

pone.0123395.g001: X ray diffraction (XRD) patterns of the raw adsorbent (curve a) and the modified adsorbent (curve b).
Mentions: The raw and functionalized diatom frustules were subjected to XRD analysis to elucidate the chemical nature of the modification. Contrary to the amorphous raw diatom frustules (curve a in Fig 1), the XRD spectrum for functionalized diatom frustules showed two distinct peaks characteristic of the crystalline presence at 2θ of 7.5 and 21.2°, corresponding to a d-spacing of 11.78 and 4.26 Å, respectively. The peak at 21.2° is attributed to the presence of quartz as previous studies have reported [11,12], whereas the peak at 7.5° can be assigned to the silanizing agent that became incorporated into the modified diatom frustules.

Bottom Line: The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume.X-ray photoelectron spectroscopy (XPS) further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III) and thiol groups, and through the surface complexation between As(III) and protonated nitrogen and hydroxyl groups.Results indicate that this functionalized bioadsorbent with a high As(III) adsorption capacity holds promise for the treatment of As(III) containing wastewater.

View Article: PubMed Central - PubMed

Affiliation: Environmental Science Institute, Zhejiang University, Hangzhou, Zhejiang, People's Republic of China; Zhejiang Provincial Key Laboratory of Organic Pollution Process and Control, Hangzhou, Zhejiang, People's Republic of China.

ABSTRACT
The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino) groups to effectively remove arsenic in its toxic As(III) form (arsenite) predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III) concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III) at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III) adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film) and internal (intraparticle) diffusion can be rate-determining for As(III) adsorption. Fourier transform infrared spectroscopy (FTIR) indicated that the thiol and amino groups potentially responsible for As(III) adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS) further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III) and thiol groups, and through the surface complexation between As(III) and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III) adsorption capacity holds promise for the treatment of As(III) containing wastewater.

No MeSH data available.


Related in: MedlinePlus