@article {54,
	title = {Hematite decorated multi-walled carbon nanotubes (α-Fe2O3/MWCNTs) as sorbents for Cu(II) and Cr(VI): comparison of hybrid sorbent performance to its nanomaterial building blocks.},
	journal = {RSC Advances},
	volume = {6},
	year = {2016},
	note = {CAPLUS AN 2016:1655141(Journal; Online Computer File)},
	month = {2016},
	pages = {99997 - 100007},
	publisher = {Royal Society of Chemistry},
	abstract = {Major hurdles in the application of engineered nanomaterials for water treatment include loss of reactive surface area arising from particle aggregation and the development of application platforms that limit their potential release into the treated water supply.  Here, we develop hybrid nanostructures through the growth of hematite (α-Fe2O3) nanoparticles, which are recognized sorbents for various heavy metals, on multi-walled carbon nanotubes (MWCNTs).  The hybrid nanostructures were synthesized via hydrolysis of ferric nitrate in the presence of carboxylated MWCNTs, and their activity as sorbents toward Cu(II) and chromate (CrO42-) was examd. as a function of pH (i.e., pH-edge expts.) and initial metal concn. (i.e., adsorption isotherms).  Characterization of α-Fe2O3/MWCNT nanostructures via Raman spectroscopy and transmission electron microscopy (TEM) with selected area electron diffraction (SAED) confirmed the deposited iron phase as α-Fe2O3.  Further, complementary acid digestions and TEM imaging revealed that the amt. (0.1 and 0.5 g g-1 α-Fe2O3/MWCNT) and size [5.9 ({\textpm}1.1) and 8.9 ({\textpm}1.5) nm, resp.] of α-Fe2O3 nanoparticles immobilized on MWCNTs were tunable during synthesis.  Generally, mass-normalized concns. of adsorbed Cu(II) and CrO42- were greatest for α-Fe2O3/MWCNT hybrids relative to adsorption on either carboxylated MWCNTs or freely suspended α-Fe2O3 nanoparticles, with evidence implicating α-Fe2O3 as the active sorbent phase in hybrid materials.  Indeed, per unit mass of available α-Fe2O3, hybrid sorbents exhibited capacities comparable to or exceeding most other iron-based sorbents for Cu(II) and CrO42- (from 220 to 470 mg Cu(II) per g α-Fe2O3 and 60 mg CrO42- per g α-Fe2O3, resp., at pH 6 and 20 {\textdegree}C).  The enhanced sorption capacity of the hybrid nanostructures is due, at least in part, to the greater available surface area of α-Fe2O3 nanoparticles immobilized on MWCNTs when compared to their more extensively aggregated state in suspension.  Notable differences in the pH-dependent trends of Cu(II) and CrO42- uptake on α-Fe2O3/MWCNT hybrids, along with differences in zeta potential measurements across pH, also suggest that the immobilized α-Fe2O3 nanoparticles may exhibit unique surface reactivity relative to their freely suspended analogs as a result of their assocn. with the neg. charged MWCNT surface. [on SciFinder(R)]},
	keywords = {hematite MWCNT copper chromium hybrid sorbent nanomaterial building block},
	isbn = {2046-2069},
	author = {Verdugo, Edgard M. and Xie, Yang and Baltrusaitis, Jonas and Cwiertny, David M.}
}
@article {88,
	title = {N-Functionalized Carbon Nanotubes As a Source and Precursor of N-Nitrosodimethylamine: Implications for Environmental Fate, Transport, and Toxicity.},
	journal = {Environmental Science \& Technology},
	volume = {48},
	year = {2014},
	note = {CAPLUS AN 2014:1233176(Journal; Online Computer File)},
	pages = {9279 - 9287},
	publisher = {American Chemical Society},
	abstract = {Hazardous byproducts may be generated during the environmental processing of engineered nanomaterials.  Here, we explore the ability of carbon nanotubes with nitrogen-contg. surface groups (N-CNTs) to generate N-nitrosodimethylamine (NDMA) during chem. disinfection.  Unexpectedly, we obsd. that com. N-CNTs with amine, amide, or N-contg. polymer (PABS) surface groups are a source of NDMA.  As-received powders can leach up to 50 ng of NDMA per mg of N-CNT in aq. suspension; presumably NDMA originates as a residue from N-CNT manufg.  Furthermore, reaction of N-CNTs with free chlorine, monochloramine, and ozone generated byproduct NDMA at yields comparable to those reported for natural org. matter.  Chlorination also altered N-CNT surface chem., with XPS indicating addn. of Cl, loss of N, and an increase in surface O.  Although these changes can increase N-CNT suspension stability, they do not enhance their acute toxicity in E. coli bioassays above that obsd. for as-received powders.  Notably, however, dechlorination of reacted N-CNTs with sulfite completely suppresses N-CNT toxicity.  Collectively, our work demonstrates that N-CNTs are both a source and precursor of NDMA, a probable human carcinogen, while chem. disinfection can produce CNTs exhibiting surface chem. and environmental behavior distinct from that of native (i.e., as-received) materials. [on SciFinder(R)]},
	keywords = {nitrogen functionalized carbon nanotube arsenic source precursor nitrosodimethylamine toxicity},
	isbn = {0013-936X},
	author = {Verdugo, Edgard M. and Krause, Caitlin and Genskow, Kelly and Han, Ying and Baltrusaitis, Jonas and Mattes, Timothy E. and Valentine, Richard L. and Cwiertny, David M.}
}
