184
exposure to gamma rays, the human body can suffer from several diseases and eventually death (Altagracia-Martinez et al. 2012).
The recovery of radioactive cesium can be performed with two main processes,
precipitation and extraction. Among several compounds, Prussian blue analogs
occupy a principal place (Vincent et al. 2015) because of one key property toward
cesium and other heavy metals sequestration: the selectivity. For instance, due to its
versatility in a wide pH range, copper hexacyanoferrate was used for Cs removal
from wastewaters (Chen et al. 2013a, b; Arisaka et al. 2015; Sangvanich et al. 2010;
Parajuli et al. 2016). However, the challenge for the utilization of Prussian blue
analog materials in large-scale applications is still open: the relatively small size of
the particles, regularly in the nano- or submicro-domain, may represent a serious
drawback especially due to the required filtration step. This engineering problem
can be solved by using, for instance, water-ink based metal hexacyanoferrate
nanoparticles (Chen et al. 2012, 2013a, b) or by using an immobilization technique
for the potassium copper hexacyanoferrate based on three-dimensional porous
hydrogel structure (Kim et al. 2017). Zheng et al. (2017) proposed a dendritic copper hexacyanoferrate/carbon nanotube approach, while a functionalized magnetic
nanocluster of sodium copper hexacyanoferrate was employed by Yang et al. (2017).
More recently, El-bahy et al. (2018) proposed a carbomer encapsulated potassium
copper hexacyanoferrate for batch techniques, where several variable were measured, evaluated, and probed. Zong et al. (2017) fabricated a composite based on
potassium copper ferrocyanide particle demonstrating the suitability of this adsorbent in a moderate acid condition. As Fig. 7.5 reports, the adsorbent selectivity for
the cesium are very interesting at pH of about 5.
To evaluate the Prussian blue analogs capabilities as exchanger materials in
nuclear wastewater and, more generally, in industrial wastewaters, the work of
Sangvanich et al. (2010) is relevant as different sorbents and matrices are considered. His study reveals not only a high affinity toward cesium but also for thallium.
Table 7.2 summarizes his study, by reporting the measured distribution coefficient
for several cations on copper hexacyanoferrate immobilized in silica and of the
Prussian Blue in seawater. Although the selectivity of both agents based on Prussian
blue are similar for a given cation, some differences are clearly evident, especially
while different pH condition are considered.
As indicated in the Sect. 7.2.2, a device based on the sorption characteristic of a
Prussian blue-based material can be used as a superior sorbent for the Cs
+
uptake if
an external force, i.e., the electricity, is used. This strategy is called electrochemically switched ion exchange, and the Fig. 7.6 displays its potentiality, while a conventional versus the electrochemically switched ion exchange method is used, as
reported by Chen et al. (2013a, b). The plot at the left indicated that both methods
can be used, but the electrochemically switched ion exchange not only turned out to
be more efficient but also reversible.
M. Berrettoni et al.
exposure to gamma rays, the human body can suffer from several diseases and eventually death (Altagracia-Martinez et al. 2012).
The recovery of radioactive cesium can be performed with two main processes,
precipitation and extraction. Among several compounds, Prussian blue analogs
occupy a principal place (Vincent et al. 2015) because of one key property toward
cesium and other heavy metals sequestration: the selectivity. For instance, due to its
versatility in a wide pH range, copper hexacyanoferrate was used for Cs removal
from wastewaters (Chen et al. 2013a, b; Arisaka et al. 2015; Sangvanich et al. 2010;
Parajuli et al. 2016). However, the challenge for the utilization of Prussian blue
analog materials in large-scale applications is still open: the relatively small size of
the particles, regularly in the nano- or submicro-domain, may represent a serious
drawback especially due to the required filtration step. This engineering problem
can be solved by using, for instance, water-ink based metal hexacyanoferrate
nanoparticles (Chen et al. 2012, 2013a, b) or by using an immobilization technique
for the potassium copper hexacyanoferrate based on three-dimensional porous
hydrogel structure (Kim et al. 2017). Zheng et al. (2017) proposed a dendritic copper hexacyanoferrate/carbon nanotube approach, while a functionalized magnetic
nanocluster of sodium copper hexacyanoferrate was employed by Yang et al. (2017).
More recently, El-bahy et al. (2018) proposed a carbomer encapsulated potassium
copper hexacyanoferrate for batch techniques, where several variable were measured, evaluated, and probed. Zong et al. (2017) fabricated a composite based on
potassium copper ferrocyanide particle demonstrating the suitability of this adsorbent in a moderate acid condition. As Fig. 7.5 reports, the adsorbent selectivity for
the cesium are very interesting at pH of about 5.
To evaluate the Prussian blue analogs capabilities as exchanger materials in
nuclear wastewater and, more generally, in industrial wastewaters, the work of
Sangvanich et al. (2010) is relevant as different sorbents and matrices are considered. His study reveals not only a high affinity toward cesium but also for thallium.
Table 7.2 summarizes his study, by reporting the measured distribution coefficient
for several cations on copper hexacyanoferrate immobilized in silica and of the
Prussian Blue in seawater. Although the selectivity of both agents based on Prussian
blue are similar for a given cation, some differences are clearly evident, especially
while different pH condition are considered.
As indicated in the Sect. 7.2.2, a device based on the sorption characteristic of a
Prussian blue-based material can be used as a superior sorbent for the Cs
+
uptake if
an external force, i.e., the electricity, is used. This strategy is called electrochemically switched ion exchange, and the Fig. 7.6 displays its potentiality, while a conventional versus the electrochemically switched ion exchange method is used, as
reported by Chen et al. (2013a, b). The plot at the left indicated that both methods
can be used, but the electrochemically switched ion exchange not only turned out to
be more efficient but also reversible.
M. Berrettoni et al.