separation and charge injection not understood for the many materials. The energy
management and energy-economy should be maintained in every step of the
photocatalytic degradation process. The efficiency also refers to the production
efficiency, such as minimization use of the raw materials and all operations. Current
trial and error approach may not be best approach to attain the high efficiency. Hence
the research direction requires serious collaboration with the chemists, physicist,
material scientist, electronics and photo-chemists which research direction utilize
every possible opportunity. Alternatively, the nanomaterials are providing wonderful opportunity for the enhancing the efficiency (Farnesi Camellone and Marx 2013;
Jabbari et al. 2016; Savage and Diallo 2005). Since the nanomaterials has high
surface to volume ratio, it provided extra catalytic centers on the photocatalytic
surfaces. Moreover, nanoparticles band gap is depending on the size of the
nanoparticles which provides the unexplored opportunity for the photocatalyst
bandgap engineering. Due to the small surface area charge separation and charge
transfer also easy in nano photocatalyst. Hence nanotechnology can empower the
photocatalytic technology and have the promise of high efficiency. In summary, the
solution of high efficient material design is short term and requires cooperation from
material design as well as research and development.
7.3.2 Recycling the Utilized Photocatalytic Materials
Recycling means utilizing the used catalyst instead of mining the materials and this
may address the earth abundant materials problem. The photocatalyst is heterogenous in nature and it can be recycled numerous times with negligible loss
photocatalytic activity which is applicable to both powder and the thin films. It is
to be mentioned that photocatalyst must be extracted from the catalytic medium after
the catalysis. Then it must clean up, reactivated and reused for the next cycle for the
catalysis. The solution is permanent but the technology for recycling process should
be developed separately. It is extremely unlikely to implement the recycling method
due to economics involved in the process. From the industrial perspective, the
recycling is money intense process and involving collection, separation, recycling
of photocatalyst, time and labor cost. Recently, magnetically recoverable catalysts
gain wide attention due to the simplicity in the process and zero loss during the
recovery. The process improves the separation efficiency and recovery. It is believed
that recycling technology completely dominated by the magnetic materials
(Ambashta and Sillanpää 2010; Hu et al. 2016; Lu et al. 2007; Zhang et al. 2010;
Zhang et al. 2016b). But the water remediation process restricts the photocatalytic
water remediation process to few magnetic materials (Mamba and Mishra 2016).
Recycling process is more of engineering and technology than the science. Hence
the problem of recycling associated with the industries and solution should industry
conducive. Another important factor to consider the while recycling process is
stability of active materials. The materials must be stable towards photons, charge
transfer, oxidation, reduction and leaching process. Due to this factor materials
7 Earth Abundant Materials for Environmental Remediation and Commercialization
209
management and energy-economy should be maintained in every step of the
photocatalytic degradation process. The efficiency also refers to the production
efficiency, such as minimization use of the raw materials and all operations. Current
trial and error approach may not be best approach to attain the high efficiency. Hence
the research direction requires serious collaboration with the chemists, physicist,
material scientist, electronics and photo-chemists which research direction utilize
every possible opportunity. Alternatively, the nanomaterials are providing wonderful opportunity for the enhancing the efficiency (Farnesi Camellone and Marx 2013;
Jabbari et al. 2016; Savage and Diallo 2005). Since the nanomaterials has high
surface to volume ratio, it provided extra catalytic centers on the photocatalytic
surfaces. Moreover, nanoparticles band gap is depending on the size of the
nanoparticles which provides the unexplored opportunity for the photocatalyst
bandgap engineering. Due to the small surface area charge separation and charge
transfer also easy in nano photocatalyst. Hence nanotechnology can empower the
photocatalytic technology and have the promise of high efficiency. In summary, the
solution of high efficient material design is short term and requires cooperation from
material design as well as research and development.
7.3.2 Recycling the Utilized Photocatalytic Materials
Recycling means utilizing the used catalyst instead of mining the materials and this
may address the earth abundant materials problem. The photocatalyst is heterogenous in nature and it can be recycled numerous times with negligible loss
photocatalytic activity which is applicable to both powder and the thin films. It is
to be mentioned that photocatalyst must be extracted from the catalytic medium after
the catalysis. Then it must clean up, reactivated and reused for the next cycle for the
catalysis. The solution is permanent but the technology for recycling process should
be developed separately. It is extremely unlikely to implement the recycling method
due to economics involved in the process. From the industrial perspective, the
recycling is money intense process and involving collection, separation, recycling
of photocatalyst, time and labor cost. Recently, magnetically recoverable catalysts
gain wide attention due to the simplicity in the process and zero loss during the
recovery. The process improves the separation efficiency and recovery. It is believed
that recycling technology completely dominated by the magnetic materials
(Ambashta and Sillanpää 2010; Hu et al. 2016; Lu et al. 2007; Zhang et al. 2010;
Zhang et al. 2016b). But the water remediation process restricts the photocatalytic
water remediation process to few magnetic materials (Mamba and Mishra 2016).
Recycling process is more of engineering and technology than the science. Hence
the problem of recycling associated with the industries and solution should industry
conducive. Another important factor to consider the while recycling process is
stability of active materials. The materials must be stable towards photons, charge
transfer, oxidation, reduction and leaching process. Due to this factor materials
7 Earth Abundant Materials for Environmental Remediation and Commercialization
209