technology over the existing ones are minimal reagent consumption, minimal sludge
production with As (hazardous waste), and disinfecting effect.
Keywords Ferrates · Arsenic removal · Drinking water treatment · Groundwater ·
Disinfecting effect · Disinfecting agents
13.1 Introduction
Ferrates have been described in the literature for the past two decades as a new type
of substance enabling versatile employment in environmental applications. Laboratory tests on the level of fundamental research proved their significant potential
applicable for water remediation (e.g., removal of metals, triazine pesticides, endocrine disruptors, cyanides, chemical warfare agents, etc., disinfecting effects (Filip
et al. 2011; Zboril et al. 2012; Prucek et al. 2013, 2015; Yates et al. 2014). Ferrates
show strong oxidation effect; their final products after the reaction—ferric oxides
and oxyhydroxides—are considered nontoxic, and, moreover, they can act as coagulants. Chemical properties of ferrates such as fast reaction with contaminants or low
reagent consumption and the resulting lower waste footprint represent an advantage
for their application compared with other commonly used technologies.
High-quality resources of drinking water have been disappearing in the Czech
Republic, hence the need to begin deploying resources of lower quality. On account
of that, research into the disinfecting effect of ferrates has been included within the
treatment scheme for arsenic removal. From a microbiological point of view, the
remediated water met the requirements for drinking water. Such a promising effect
may have been caused by the combination of several factors: disinfecting effect of
ferrates reacting in water environment, sorption of microorganisms on the formed
nanoparticles of iron oxide/oxyhydroxide, and ultrafiltration with the pore size of
0.45 μm.
13.2 Characterization of Ferrates Used for the Testing
For the purpose of laboratory tests aimed at arsenic removal from groundwater, we
used commercial ferrates. In this case, these were commercial ferrates from NANO
IRON company (Czech Republic) containing about 33 wt.% of K 2 FeO 4 in aqueous
solution (UV–VIS measurement done by spectrophotometry at 510 nm and subsequent calculation according to Bielski and Thomas (1987). Detailed characterization
of the commercial ferrate is provided in Tables 13.1 and 13.2.
The commercial ferrate is formed by coarse-grained aggregates of a black-violet
or almost black color containing crystals of ferrates Fe(V) and Fe(VI). When it is
dissolved in water, ferrate Fe(V) disproportionates to Fe(VI) and Fe(III) in the ratio
about 2:1. Ferrates in aqueous solution exist mainly in the form of Fe(VI). Fe(VI) is
unstable in aqueous solution, after 24 h the concentration reaches only about 10% of
300
M. Heřmánková et al.
production with As (hazardous waste), and disinfecting effect.
Keywords Ferrates · Arsenic removal · Drinking water treatment · Groundwater ·
Disinfecting effect · Disinfecting agents
13.1 Introduction
Ferrates have been described in the literature for the past two decades as a new type
of substance enabling versatile employment in environmental applications. Laboratory tests on the level of fundamental research proved their significant potential
applicable for water remediation (e.g., removal of metals, triazine pesticides, endocrine disruptors, cyanides, chemical warfare agents, etc., disinfecting effects (Filip
et al. 2011; Zboril et al. 2012; Prucek et al. 2013, 2015; Yates et al. 2014). Ferrates
show strong oxidation effect; their final products after the reaction—ferric oxides
and oxyhydroxides—are considered nontoxic, and, moreover, they can act as coagulants. Chemical properties of ferrates such as fast reaction with contaminants or low
reagent consumption and the resulting lower waste footprint represent an advantage
for their application compared with other commonly used technologies.
High-quality resources of drinking water have been disappearing in the Czech
Republic, hence the need to begin deploying resources of lower quality. On account
of that, research into the disinfecting effect of ferrates has been included within the
treatment scheme for arsenic removal. From a microbiological point of view, the
remediated water met the requirements for drinking water. Such a promising effect
may have been caused by the combination of several factors: disinfecting effect of
ferrates reacting in water environment, sorption of microorganisms on the formed
nanoparticles of iron oxide/oxyhydroxide, and ultrafiltration with the pore size of
0.45 μm.
13.2 Characterization of Ferrates Used for the Testing
For the purpose of laboratory tests aimed at arsenic removal from groundwater, we
used commercial ferrates. In this case, these were commercial ferrates from NANO
IRON company (Czech Republic) containing about 33 wt.% of K 2 FeO 4 in aqueous
solution (UV–VIS measurement done by spectrophotometry at 510 nm and subsequent calculation according to Bielski and Thomas (1987). Detailed characterization
of the commercial ferrate is provided in Tables 13.1 and 13.2.
The commercial ferrate is formed by coarse-grained aggregates of a black-violet
or almost black color containing crystals of ferrates Fe(V) and Fe(VI). When it is
dissolved in water, ferrate Fe(V) disproportionates to Fe(VI) and Fe(III) in the ratio
about 2:1. Ferrates in aqueous solution exist mainly in the form of Fe(VI). Fe(VI) is
unstable in aqueous solution, after 24 h the concentration reaches only about 10% of
300
M. Heřmánková et al.