The manufacture of significant quantities of nanomaterials will inevitably lead to
the introduction of these materials into the environment. The understanding of the
characteristics and the fate of these nanomaterials in water is crucial to evaluate
their environmental implication and potential risk for human exposure. This
research investigated the characteristics, dispersion and stability of two important
categories of nanomaterials, metal oxide nanoparticles and quantum dots (QDs)
in different aquatic environments, as well as their propensity to be removed by
portable water treatment. Lab-synthesized hematite was prepared as individual
nanoparticles; whereas, all commercial metal oxide nanoparticles were
aggregates as received. Neither sonication nor dispersant could not break up
these aggregates to primary nanoparticles. It may attribute to chemical bonding
during the synthesis or storage. Except silica, metal oxide nanoparticle
aggregates aggregated further in 0.01 M KCl solution. The stability of silica may
be related to its low pH value of zero point of charge (pHzpc) and low Hamaker
constant. Addition of 4 mg/L natural organic matter (NOM) could stabilize metal oxide nanoparticles by
imparting negative charge to their surface and producing an increase in absolute
surface potential. Compared with metal oxide nanoparticles, most QD particles
presented as individual nanoparticles, but they also contained a few aggregates.
Due to carboxyl functional groups bound on QDs surface, QDs remained stable
unless divalent or trivalent cations were introduced to form complexes with QDs.
Portable water treatment studies showed that these nanoparticles were relatively
difficult to be removed from water only by coagulation, flocculation and
sedimentation processes and 0.45 µm filtration enhanced their removal. Includes 9 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 2.4 MB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 40 |
| Published : | 06/01/2007 |
