et al. 2017). In addition, sulfidated particles are more efficient for the formation of
ROS in aerobic conditions than unamended iron particles (Song et al. 2017;
Rayaroth et al. 2017), allowing the development of the technology for wastewater
treatment.
It is also possible to use sodium dithionite in combination with ZVI particles to
extend the reactive lifetime of iron particles in alkaline conditions by dissolving and
reducing Fe 2 O 3 and Fe(OH) 3 layer to regenerate Fe(II) species (Xie and Cwiertny
2010). The addition of sodium dithionite or other soluble reductant to iron particles
enhance reduction rates of dechlorination of chloromethanes, chloroethanes,
chloroethenes such as recalcitrant 1,2-DCA, and chlorobenzenes (Vermeul et al.
2000; Lee 2004; Brown 2010; Nunez Garcia et al. 2016).
6.3.2.5 Combination of Iron-Based Particles with Other Techniques
In field application, abiotic remediation processes cannot be considered separately
from biotic processes (Brown et al. 2009; Koenig et al. 2016; Němeček et al. 2016;
Wang et al. 2016; Cecchinc et al. 2017; You et al. 2017; Xu et al. 2017; Vogel et al.
2018). Indeed, iron particles have several effects on the microbial activity and
growth. These effects are generally dose- and species-dependent and are influenced
by the environmental conditions, and both synergetic and inhibitory effects are
reported in the literature (Xie et al. 2017). The production of H 2 resulting from
iron corrosion can stimulate dehalorespiring bacteria (Bruton et al. 2015). In addition, the polymer coating used for the stabilization of the particles may act as a
fermentable substrate (Kirschling et al. 2010, 2011; Kocur et al. 2015, 2016).
However, some inhibitory effects of nZVI particles on sulfate reducing bacteria
are also reported (Kumar et al. 2014b). In porous media, the mobility of iron particles
can be affected by the presence of a natural biofilm (Crampon et al. 2018).
In addition, a lot of techniques can be used in combination to enhance ZVI
technology (Jiang et al. 2018), such as physical enhanced technologies (e.g.,
ultrasonic-assisted technology, UV-visible light, microwave or weak magnetic
field) (Guan et al. 2015), advanced oxidation processes, e.g., modified Fenton
process (Fu et al. 2014a) or ZVI-activated persulfate (Al-Shamsi and Thomson
2013), electrokinetic remediation (Fan et al. 2016c; Xiong et al. 2018) or the
combination of ZVI with phytoremediation (Gong et al. 2018).
6.3.2.6 Toxicity
Potential risks of nZVI particles for in situ application in soils and groundwater
remediation are still not clearly established (Grieger et al. 2010; Jang et al. 2014).
Studies on other nanoscale materials, such as carbon nanotubes or fullerenes, have
shown specific evidence for human and ecological risk, but iron nanoparticles are
not as small, reactive, persistent, or mobile (Reijnders 2006; Tratnyek and Johnson
312
R. Rodrigues et al.
ROS in aerobic conditions than unamended iron particles (Song et al. 2017;
Rayaroth et al. 2017), allowing the development of the technology for wastewater
treatment.
It is also possible to use sodium dithionite in combination with ZVI particles to
extend the reactive lifetime of iron particles in alkaline conditions by dissolving and
reducing Fe 2 O 3 and Fe(OH) 3 layer to regenerate Fe(II) species (Xie and Cwiertny
2010). The addition of sodium dithionite or other soluble reductant to iron particles
enhance reduction rates of dechlorination of chloromethanes, chloroethanes,
chloroethenes such as recalcitrant 1,2-DCA, and chlorobenzenes (Vermeul et al.
2000; Lee 2004; Brown 2010; Nunez Garcia et al. 2016).
6.3.2.5 Combination of Iron-Based Particles with Other Techniques
In field application, abiotic remediation processes cannot be considered separately
from biotic processes (Brown et al. 2009; Koenig et al. 2016; Němeček et al. 2016;
Wang et al. 2016; Cecchinc et al. 2017; You et al. 2017; Xu et al. 2017; Vogel et al.
2018). Indeed, iron particles have several effects on the microbial activity and
growth. These effects are generally dose- and species-dependent and are influenced
by the environmental conditions, and both synergetic and inhibitory effects are
reported in the literature (Xie et al. 2017). The production of H 2 resulting from
iron corrosion can stimulate dehalorespiring bacteria (Bruton et al. 2015). In addition, the polymer coating used for the stabilization of the particles may act as a
fermentable substrate (Kirschling et al. 2010, 2011; Kocur et al. 2015, 2016).
However, some inhibitory effects of nZVI particles on sulfate reducing bacteria
are also reported (Kumar et al. 2014b). In porous media, the mobility of iron particles
can be affected by the presence of a natural biofilm (Crampon et al. 2018).
In addition, a lot of techniques can be used in combination to enhance ZVI
technology (Jiang et al. 2018), such as physical enhanced technologies (e.g.,
ultrasonic-assisted technology, UV-visible light, microwave or weak magnetic
field) (Guan et al. 2015), advanced oxidation processes, e.g., modified Fenton
process (Fu et al. 2014a) or ZVI-activated persulfate (Al-Shamsi and Thomson
2013), electrokinetic remediation (Fan et al. 2016c; Xiong et al. 2018) or the
combination of ZVI with phytoremediation (Gong et al. 2018).
6.3.2.6 Toxicity
Potential risks of nZVI particles for in situ application in soils and groundwater
remediation are still not clearly established (Grieger et al. 2010; Jang et al. 2014).
Studies on other nanoscale materials, such as carbon nanotubes or fullerenes, have
shown specific evidence for human and ecological risk, but iron nanoparticles are
not as small, reactive, persistent, or mobile (Reijnders 2006; Tratnyek and Johnson
312
R. Rodrigues et al.