Application of Zero-valent Iron Nanoparticles for Environmental Clean Up - Advanced Materials for Agriculture, Food and Environmental Safety - page 409

dif erent dispersants (aluminum lactate, sodium lactate, ethyl lactate, aspar-
tic acid, polyacrylic acid, 2-hydroxypropyl-β-cyclodextrin, β-cyclodextrin
and methyl-cyclodextrin) and found improved stability and transport for
the all over bare nFe 0 , with aluminum lactate as the best stabilizer demon-
strating highest elution from soil column. Besides these polymers, several
researchers have also used microemulsions, starch, guar gum, silica, etc.
[25, 85, 116], as delivery vehicles for transport of nFe 0 in porous media.
Another interesting approach towards improving the mobility of
nanoparticles in soil is the application of electric i eld, i.e., Electrokinetics.
Ya n g et al. [117] reported that under the inl uence of an electric magnetic
i eld, polyacrylic acid-modii ed nFe 0 could be ef ectively transported hori-
zontally through packed loamy sand soil (18-25 m). Pamukcu et al. [118]
also showed ef ective movement of polymer-coated nFe 0 from anode to
cathode through clay soil. h ey further reported in addition to enhanced
transport, electric i eld also activates nFe 0 . Reddy et al. [119] investigated
the electrokinetic delivery of lactate modii ed nanoscale iron particles
(LM-NIP) into low permeability kaolin soil, spiked with dinitrotoluene
(DNT). h e application of constant voltage gradient (1VDC/cm) pro-
duced electro-osmotic l ow in the soil, which in combination with electro-
migration enhanced the extent of transport of LM-NIP in the soil. Besides
increasing the transport, enhanced degradation of the contaminant via
electrokinetic remediation is an additional benei t of this approach [120].
Some recent studies also successfully demonstrated the ef ectiveness of
electrokinetics in enhancing nFe 0 transport and contaminant degradation
in several nFe 0 permeable reactive barriers [121, 122].
14.6 IntegratedApproach
h e integrated approach exploits the reductive capabilities of nFe 0 - mediated
abiotic degradation and biotic degradation/microbial degradation either
sequentially or concurrently. h e combination of nFe 0 aided remediation
and microbial degradation processes, could provide an ef ective method
for degradation of most recalcitrant compounds. Generally, highly chlori-
nated compounds with i ve or more chlorine atoms such as polychlorinated
biphenyls remain biorefactory to aerobic bacteria, whereas low chlorinated
compounds degrade easily in the environment. h e basic concept of an
integrated system is to transform highly chlorinated non-biodegradable
compounds abiotically through nFe 0 to less chlorinated compounds, which
can then be easily subjected to degradation by biotic communities under
aerobic/anaerobic conditions.