and in that way they eliminate formation of the iron oxide-passivation layer on nZVI
surface, thus extending the operational life of nZVI (Chang and Cheng 2006).
Moreover, electro-migration phenomena provide inhibition of sedimentation and
aggregation of nZVI, i.e., their mobility and advection is increased (Černík et al.
2019). Subsequently, long-term and high reactivity of nZVI is guaranteed. In
Fig. 2.9b is depicted a model example of the merge of the two techniques for
hexavalent chromium (Cr(VI)) removal, where nZVI is positioned as a reactive
wall and constant electric potential gradient was applied in order to move the
electrolyte solution within the soil cell. Weng et al. (2007) showed the successful
incorporation of nZVI and EK by presenting the synergetic effect of this combination in hexavalent chromium reduction. Chowdhury et al. (2012) investigated the
impact of an external electric field on nZVI mobility in two different porous media.
Due to the surface properties of nZVI, the nZVI injection into the media was
preferably applied near the cathode. The obtained results revealed the potential of
the minimization of nZVI oxidation and the enhancement of nZVI migration when
electrokinetics was applied.
Moreover, electrokinetics offers the flexibilty to involve any nZVI based material
in such processes. For instance, Reddy et al. (2011) studied the transport and
reactivity of aluminum lactate modified nZVI in dinitrotoluene contaminated soils
under applied electric potential, showing the altered properties both in mobility and
Fig. 2.9 (a) Basics of electrokinetic phenomena (adapted from Glendinning et al. (2007) with
permission), (b) Model of the combination of nZVI and electrokinetics process setup (adapted
from Weng et al. (2007) with permission), (c) Total iron distribution on the electrophoretic cell
(adapted from Gomes et al. (2013) with permission) (d) The effect of electrokinetics on water
chemistry (adapted from Chang and Cheng (2006) with permission) (e) The effect of electrokinetics
on TCE removal (adapted from Yang and Chang (2011) with permission)
36
T. Phenrat et al.
surface, thus extending the operational life of nZVI (Chang and Cheng 2006).
Moreover, electro-migration phenomena provide inhibition of sedimentation and
aggregation of nZVI, i.e., their mobility and advection is increased (Černík et al.
2019). Subsequently, long-term and high reactivity of nZVI is guaranteed. In
Fig. 2.9b is depicted a model example of the merge of the two techniques for
hexavalent chromium (Cr(VI)) removal, where nZVI is positioned as a reactive
wall and constant electric potential gradient was applied in order to move the
electrolyte solution within the soil cell. Weng et al. (2007) showed the successful
incorporation of nZVI and EK by presenting the synergetic effect of this combination in hexavalent chromium reduction. Chowdhury et al. (2012) investigated the
impact of an external electric field on nZVI mobility in two different porous media.
Due to the surface properties of nZVI, the nZVI injection into the media was
preferably applied near the cathode. The obtained results revealed the potential of
the minimization of nZVI oxidation and the enhancement of nZVI migration when
electrokinetics was applied.
Moreover, electrokinetics offers the flexibilty to involve any nZVI based material
in such processes. For instance, Reddy et al. (2011) studied the transport and
reactivity of aluminum lactate modified nZVI in dinitrotoluene contaminated soils
under applied electric potential, showing the altered properties both in mobility and
Fig. 2.9 (a) Basics of electrokinetic phenomena (adapted from Glendinning et al. (2007) with
permission), (b) Model of the combination of nZVI and electrokinetics process setup (adapted
from Weng et al. (2007) with permission), (c) Total iron distribution on the electrophoretic cell
(adapted from Gomes et al. (2013) with permission) (d) The effect of electrokinetics on water
chemistry (adapted from Chang and Cheng (2006) with permission) (e) The effect of electrokinetics
on TCE removal (adapted from Yang and Chang (2011) with permission)
36
T. Phenrat et al.