Chapter 11
The Use of Nanomaterials in Electro-Fenton
and Photoelectro-Fenton Processes
Ignasi Sirés and Enric Brillas
Abstract Nowadays, electro-Fenton and photoelectro-Fenton are considered two of
the best electrochemical advanced oxidation processes to ensure fast degradation of
organic pollutants and inactivation of toxic pathogens. Despite their apparent simplicity, two critical factors must be carefully controlled in order to enhance the
production of
•
OH from homogeneous Fenton’s reaction: the H 2 O 2
electrogeneration from cathodic O 2 reduction, and the characteristics of metal
species employed to catalyze the quick decomposition of H 2 O 2 . In conventional
electrochemical Fenton-based systems, the cathodes are made of either raw carbon
powder or massive carbon pieces since these materials are known to promote the
two-electron reduction of O 2 to yield H 2 O 2 , whereas Fe(II) or Fe(III) salts are added
to allow homogeneous catalysis at optimum pH ~3. On the basis of this concept,
good progress has been made when working with nanomaterials because the
increased specific surface area provides: (i) more active cathode surfaces to produce
H 2 O 2 ; (ii) better heterogeneous catalysts, which may react to a larger extent with
H 2 O 2 , within a wider pH range; (iii) a larger absorption of photons, promoting
photoreduction and photooxidation reactions; and (iv) a larger area to adsorb
pollutants that can be further degraded. As will be discussed in this chapter, most
of the work has addressed the use of pristine, functionalized, and decorated
nanocarbons as cathodes; the synthesis of nanocatalysts containing iron since this
is the best metal for Fenton’s reaction; and the preparation of nanostructured anodes.
Keywords Carbon felt · Carbon nanotubes · Electrochemical reactor · Gas
diffusion · Graphene · Heterogeneous catalysis · Homogeneous catalysis · Hydrogen
peroxide · Electro-Fenton · Nanomaterials · Photocatalysis · Photoelectro-Fenton ·
Surface functionalization · Water treatment
I. Sirés (*) · E. Brillas
Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química
Física, Facultat de Química, Universitat de Barcelona, Barcelona, Spain
e-mail: i.sires@ub.edu
© Springer Nature Switzerland AG 2020
J. Filip et al. (eds.), Advanced Nano-Bio Technologies for Water and Soil Treatment,
Applied Environmental Science and Engineering for a Sustainable Future,
https://doi.org/10.1007/978-3-030-29840-1_11
257
The Use of Nanomaterials in Electro-Fenton
and Photoelectro-Fenton Processes
Ignasi Sirés and Enric Brillas
Abstract Nowadays, electro-Fenton and photoelectro-Fenton are considered two of
the best electrochemical advanced oxidation processes to ensure fast degradation of
organic pollutants and inactivation of toxic pathogens. Despite their apparent simplicity, two critical factors must be carefully controlled in order to enhance the
production of
•
OH from homogeneous Fenton’s reaction: the H 2 O 2
electrogeneration from cathodic O 2 reduction, and the characteristics of metal
species employed to catalyze the quick decomposition of H 2 O 2 . In conventional
electrochemical Fenton-based systems, the cathodes are made of either raw carbon
powder or massive carbon pieces since these materials are known to promote the
two-electron reduction of O 2 to yield H 2 O 2 , whereas Fe(II) or Fe(III) salts are added
to allow homogeneous catalysis at optimum pH ~3. On the basis of this concept,
good progress has been made when working with nanomaterials because the
increased specific surface area provides: (i) more active cathode surfaces to produce
H 2 O 2 ; (ii) better heterogeneous catalysts, which may react to a larger extent with
H 2 O 2 , within a wider pH range; (iii) a larger absorption of photons, promoting
photoreduction and photooxidation reactions; and (iv) a larger area to adsorb
pollutants that can be further degraded. As will be discussed in this chapter, most
of the work has addressed the use of pristine, functionalized, and decorated
nanocarbons as cathodes; the synthesis of nanocatalysts containing iron since this
is the best metal for Fenton’s reaction; and the preparation of nanostructured anodes.
Keywords Carbon felt · Carbon nanotubes · Electrochemical reactor · Gas
diffusion · Graphene · Heterogeneous catalysis · Homogeneous catalysis · Hydrogen
peroxide · Electro-Fenton · Nanomaterials · Photocatalysis · Photoelectro-Fenton ·
Surface functionalization · Water treatment
I. Sirés (*) · E. Brillas
Laboratori d’Electroquímica dels Materials i del Medi Ambient, Departament de Química
Física, Facultat de Química, Universitat de Barcelona, Barcelona, Spain
e-mail: i.sires@ub.edu
© Springer Nature Switzerland AG 2020
J. Filip et al. (eds.), Advanced Nano-Bio Technologies for Water and Soil Treatment,
Applied Environmental Science and Engineering for a Sustainable Future,
https://doi.org/10.1007/978-3-030-29840-1_11
257