TY - JOUR
T1 - Zn sorption mechanisms onto sheathed Leptothrix discophora and the impact of the nanoparticulate biogenic Mn oxide coating
AU - Boonfueng, Thipnakarin
AU - Axe, Lisa
AU - Yee, Nathan
AU - Hahn, Dittmar
AU - Ndiba, Peter K.
N1 - Funding Information:
The authors gratefully acknowledge the support of the National Science Foundation under Grant No. BES 0089903 and the DuPont Young Professor's Grant. The authors thank Kaumudi Pandya for technical support at beamline X11A. Research carried out at NSLS, Brookhaven National Laboratory, was supported in part by the U.S. Department of Energy, Division of Materials Sciences and Division of Chemical Sciences, under Contract No. DE-AC02-98CH10886. In addition, beamline X11 at NSLS was supported by the Office of Naval Research.
PY - 2009/5/15
Y1 - 2009/5/15
N2 - Zinc sorption on sheathed Leptothrix discophora bacterium, the isolated extracellular polymeric substances (EPS) sheath, and Mn oxide-coated bacteria was investigated with macroscopic and spectroscopic techniques. Complexation with L. discophora was dominated by the outer membrane phosphoryl groups of the phospholipid bilayer while sorption to isolated EPS was dominated by carboxyl groups. Precipitation of nanoparticulate Mn oxide coatings on the cell surface increased site capacity by over twenty times with significant increase in metal sorption. XAS analysis of Zn sorption in the coated system showed Mn oxide phase contributions of 18 to 43% through mononuclear inner-sphere complexes. The coordination environments in coprecipitation samples were identical to those of sorption samples, indicating that, even in coprecipitation, Zn is not incorporated into the Mn oxide structure. Rather, through enzymatic oxidation by L. discophora, Mn(II) is oxidized and precipitated onto the biofilm providing a large surface for metal sequestration. The nanoparticulate Mn oxide coating exhibited significant microporosity (75%) suggesting contributions from intraparticle diffusion. Transient studies conducted over 7 months revealed a 170% increase in Zn loading. However, the intraparticle diffusivity of 10-19 cm2 s-1 is two orders of magnitude smaller than that for abiotic Mn oxide which we attribute to morphological changes such as reduced pore sizes in the nanoparticulate oxide. Our results demonstrate that the cell-bound Mn oxide particles can sorb significant amounts of Zn over long periods of time representing an important surface for sequestration of metal contaminants.
AB - Zinc sorption on sheathed Leptothrix discophora bacterium, the isolated extracellular polymeric substances (EPS) sheath, and Mn oxide-coated bacteria was investigated with macroscopic and spectroscopic techniques. Complexation with L. discophora was dominated by the outer membrane phosphoryl groups of the phospholipid bilayer while sorption to isolated EPS was dominated by carboxyl groups. Precipitation of nanoparticulate Mn oxide coatings on the cell surface increased site capacity by over twenty times with significant increase in metal sorption. XAS analysis of Zn sorption in the coated system showed Mn oxide phase contributions of 18 to 43% through mononuclear inner-sphere complexes. The coordination environments in coprecipitation samples were identical to those of sorption samples, indicating that, even in coprecipitation, Zn is not incorporated into the Mn oxide structure. Rather, through enzymatic oxidation by L. discophora, Mn(II) is oxidized and precipitated onto the biofilm providing a large surface for metal sequestration. The nanoparticulate Mn oxide coating exhibited significant microporosity (75%) suggesting contributions from intraparticle diffusion. Transient studies conducted over 7 months revealed a 170% increase in Zn loading. However, the intraparticle diffusivity of 10-19 cm2 s-1 is two orders of magnitude smaller than that for abiotic Mn oxide which we attribute to morphological changes such as reduced pore sizes in the nanoparticulate oxide. Our results demonstrate that the cell-bound Mn oxide particles can sorb significant amounts of Zn over long periods of time representing an important surface for sequestration of metal contaminants.
KW - Biogenic manganese oxide
KW - Diffusion
KW - Extracellular polymeric substances
KW - Intraparticle
KW - Leptothrix discophora
KW - Sheath
KW - XAS
KW - Zn
KW - coprecipitation
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U2 - 10.1016/j.jcis.2009.02.033
DO - 10.1016/j.jcis.2009.02.033
M3 - Article
C2 - 19268965
AN - SCOPUS:63249113247
SN - 0021-9797
VL - 333
SP - 439
EP - 447
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
IS - 2
ER -