Environmental Engineering Reference
In-Depth Information
29
Humic Functional Derivatives anD
nanocoatings For remeDiation oF
actiniDe-contaminateD environments
Irina V. Perminova
1
, Stepan N. Kalmykov
1
, Natalia S. Shcherbina
1,2
, Sergey A.
Ponomarenko
1,3
, Vladimir A. Kholodov
1,4
, Alexander P. Novikov
5
,
Richard G. Haire
6
, and Kirk Hatfield
7
1
Chemistry Department, Lomonosov Moscow State University, Moscow, Russia
2
Paul Scherrer Institute (PSI), Villigen, Switzerland
3
Enikolopov Institute of Synthetic Polymeric Materials of RAS, Moscow, Russia
4
Dokuchaev Soil Science Institute of RAAS, Moscow, Russia
5
Vernadsky Institute of Geochemistry and Analytical Chemistry of RAS, Moscow, Russia
6
Oak Ridge National Laboratory, Oak Ridge, TN, USA
7
Engineering School of Sustainable Infrastructure & Environment, University of Florida, Gainesville, FL, USA
29.1
introDuction
Actinides in higher-valence states (e.g., V and VI) represent one of the most difficult classes of contaminants due to both their
high radiotoxicity and mobility. The interaction of actinides with other materials is an important topic affecting migration,
release, and natural and designed controls within the environment. Actinides interact strongly with humic substances (HS),
many of which occur naturally in both mobile and immobile forms [1-8]. HS can enhance actinide solubility through
complexation and by forming stable colloids. If HS exist as coatings on mineral surfaces, they can aid actinide retention on
these surfaces. Both methods of control of actinide migration in the environment are shown in Figure 29.1.
HS are natural hyperbranched polyelectrolytes with a vast functional periphery dominated by carboxyl and hydroxyl
groups. HS account for 50-80% of the organic carbon in soils, natural waters, and bottom sediments [9]. They are characterized
with substantial molecular heterogeneity and disordered structures, which contribute to the longevity of HS spanning from
hundreds to thousands of years. The recalcitrant nature of HS is of particular relevance for soil/aquifer remediation
technologies predicated on a reactive matrix that is not consumed by microorganisms during remediation. On the other hand,
the structural complexity inherent in HS (illustrated by Fig. 29.2) creates opportunities for a broad range of chemical
interactions.
These HS can be oxidized by strong oxidants; act as reducing agents; take part in protolytic, ion exchange, and complexation
reactions; participate in donor-acceptor interactions; engage in hydrogen bonding; and take part in van-der-Waals interactions
[10]. Hence, the HS can interact practically with all chemicals released to the environment. This unique constellation of reactive
features strongly suggests that HS have the potential to address a broad spectrum of needs within the focal area of environmental
remediation [11], which is confirmed by multiple examples of actual remedial applications [12-14]. However, despite multiple
