higher bacteria removal efficiency compared to pure g-C 3 N 4 and m-Bi 2 O 4 . This is
due to the direct generation of H 2 O 2 , and the reduction of O 2 by the m-Bi 2 O 4 -
graphitic carbon nitride (Xia et al. 2017). Similar results were also reported by Wang
et al. (2017b).
In general, combining graphitic carbon nitride with other materials such as Ag
and Bi showed high charge diffusion pathway, enhanced separation of
photogenerated charges, and high reactive oxygen species generation. Therefore, it
would be useful to find the proper posttreatment and method for the recovery of the
photocatalytic material. This will be a critical factor in the future to apply these
materials on a large scale under visible light for water/wastewater disinfection.
7.3 Natural Minerals as Photocatalysts for Water
Disinfection
Currently, nanostructured materials are a promising technology for water disinfection. Therefore, more efforts are taking place in design and material synthesis for
large-scale applications. However, it is required to build different procedures for the
fabrication and manufacturing of these materials taking into consideration energy
consumption. This is aligned with the so-called water–energy nexus.
Minerals which are found naturally in the form of solid substance that is molded
through biogeochemical processes present distinct properties and chemical composition. These minerals represent a promising method for the disinfection process that
can be applied on a large scale. Peng et al. (2017) studied the feasibility of using
natural minerals such as natural magenetic sphalerite in large scale for disinfection
process in their research, and they developed batch cylindrical reactor of 5 L with a
plastic stirrer and a magnetic field generator to hold the natural minerals. They
showed that it thoroughly disinfected E. coli, S. aureus, M. barkeri, and B. subtilis
within three rotations in 120 min under sunlight irradiation. In addition to this, the
authors claimed that after water disinfection, they could recycle natural minerals as
cost-effective photocatalyst. However, the disinfection ability decreased over time
due to the decomposition of the bacterial cells and the accumulations of the biomass
on the mineral active sites.
Recent publications have provided evidence for natural minerals such as natural
magnetic sphalerite (NMS) as outstanding composites for water disinfection and
organic compound degradation in practical application (Chen et al. 2011, 2013; Li
et al. 2008b, 2009; Xia et al. 2013). However, when compared with fabricated
nanostructured materials, NMS has a lower disinfection activity. This could be due
to its large size and reduced specific surface areas. To increase their efficiency for
bacterial disinfection and to enhance their stability, some researchers proposed the
modification of natural minerals such as pyrrhotite using thermal calcination (Xia
et al. 2015a). This opens the opportunity for the complete disinfection of bacteria cell
at a low cost with the potential application at large scale.
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T. G. Ambaye et al.
due to the direct generation of H 2 O 2 , and the reduction of O 2 by the m-Bi 2 O 4 -
graphitic carbon nitride (Xia et al. 2017). Similar results were also reported by Wang
et al. (2017b).
In general, combining graphitic carbon nitride with other materials such as Ag
and Bi showed high charge diffusion pathway, enhanced separation of
photogenerated charges, and high reactive oxygen species generation. Therefore, it
would be useful to find the proper posttreatment and method for the recovery of the
photocatalytic material. This will be a critical factor in the future to apply these
materials on a large scale under visible light for water/wastewater disinfection.
7.3 Natural Minerals as Photocatalysts for Water
Disinfection
Currently, nanostructured materials are a promising technology for water disinfection. Therefore, more efforts are taking place in design and material synthesis for
large-scale applications. However, it is required to build different procedures for the
fabrication and manufacturing of these materials taking into consideration energy
consumption. This is aligned with the so-called water–energy nexus.
Minerals which are found naturally in the form of solid substance that is molded
through biogeochemical processes present distinct properties and chemical composition. These minerals represent a promising method for the disinfection process that
can be applied on a large scale. Peng et al. (2017) studied the feasibility of using
natural minerals such as natural magenetic sphalerite in large scale for disinfection
process in their research, and they developed batch cylindrical reactor of 5 L with a
plastic stirrer and a magnetic field generator to hold the natural minerals. They
showed that it thoroughly disinfected E. coli, S. aureus, M. barkeri, and B. subtilis
within three rotations in 120 min under sunlight irradiation. In addition to this, the
authors claimed that after water disinfection, they could recycle natural minerals as
cost-effective photocatalyst. However, the disinfection ability decreased over time
due to the decomposition of the bacterial cells and the accumulations of the biomass
on the mineral active sites.
Recent publications have provided evidence for natural minerals such as natural
magnetic sphalerite (NMS) as outstanding composites for water disinfection and
organic compound degradation in practical application (Chen et al. 2011, 2013; Li
et al. 2008b, 2009; Xia et al. 2013). However, when compared with fabricated
nanostructured materials, NMS has a lower disinfection activity. This could be due
to its large size and reduced specific surface areas. To increase their efficiency for
bacterial disinfection and to enhance their stability, some researchers proposed the
modification of natural minerals such as pyrrhotite using thermal calcination (Xia
et al. 2015a). This opens the opportunity for the complete disinfection of bacteria cell
at a low cost with the potential application at large scale.
226
T. G. Ambaye et al.