9.4 Future Remarks and Limitations
During the twentieth century and for future enhancing outlook, one of the main
universal fears should be environmental remediation aspects. The required energy for
remediation and environmental have close dependence about numerous issues
having interplaying effects. The ultimate goal of green remediation for minimizing
the greenhouse gas emissions needs most spending efforts. The well-known different
nanomaterials have been introduced to achieve detection and elimination of pathogens. The respected nanomaterials can act through applicable routes with high
sensitivity, lower cost, in-line and real-time detection, lower turnaround times, and
more throughput and transportability in environmental purification. Among them,
nanomaterials of metal oxide and metal especially chemical-functionalized ones can
be utilized for removal of aqueous and aerial organic pollutants. Further improvements have to be exerted in selective and complete photocatalytic remediation
through degradation of contaminants to non-toxic products to changing of pH and
concentration of chemical staffs and cost optimization. TiO 2 has been considered
one of the most effective ones because of its stability and some other advantages.
However, several efforts have been and are being followed to decrease the major
failure of TiO 2 to enhance usage in a huge area of solar light for more asked
applications. The original importance of sophistication of proper band gap and
chemistry of surface/interface addressed the required researches. The appropriate
studies are (i) usage of metals–non-metals having general suitable characters as
semiconductor, surface plasmon resonance, and so on, (ii) introduction of novel
composite compounds; (iii) study of the effect of dopants–additives–sensitizers;
(iv) finding the catalytic mechanism; (v) production of thin films of photocatalysts
within titania, alumina, stainless steel, and molecular sieves; (vi) enhancing the
effective surface area of photocatalyst; (vii) development of more sensitive
photocatalyst in natural sunlight against of fictional light; and (viii) applying of
diverse synthesis methods such as hydrothermal, co-precipitation, electrochemical,
sol–gel, and so on. Another important challenge regarded to designing of appropriate
photoreactor and the commercial concerns. Despite the great contents of mercantile
contaminants needing remedy, the running conditions of technology should not be
enough. However, at first an effective multiphasic impact of pollutant, oxygen, solar
light, and photocatalyst is required. In order to commercialize of scale implementation for reliable scale-up, the specification of eminent factors and simulation of a
reliable rate declaration are necessary. Investigations are still pursuing to improve
quantum yield and maximize the impact of substances and photons regarding
fluctuations in solar irradiation. Nonetheless, designing of photoreactors are
followed according to alternative and approximate kinetic statements. Main designs
of a photoreactor are performed for concentrating collector–reactor, compound
parabolic collector–reactor, and non-concentrating collector one (Blanco et al.
2009; Braham and Harris 2009; Spasiano et al. 2015). Of the related more routine
designs, compound parabolic collector–reactor includes more advantages about
utilizing both of beam and reactive components and is resulted as the most modern
9 Nanomaterials for the Photoremediation of Pollutants
307
During the twentieth century and for future enhancing outlook, one of the main
universal fears should be environmental remediation aspects. The required energy for
remediation and environmental have close dependence about numerous issues
having interplaying effects. The ultimate goal of green remediation for minimizing
the greenhouse gas emissions needs most spending efforts. The well-known different
nanomaterials have been introduced to achieve detection and elimination of pathogens. The respected nanomaterials can act through applicable routes with high
sensitivity, lower cost, in-line and real-time detection, lower turnaround times, and
more throughput and transportability in environmental purification. Among them,
nanomaterials of metal oxide and metal especially chemical-functionalized ones can
be utilized for removal of aqueous and aerial organic pollutants. Further improvements have to be exerted in selective and complete photocatalytic remediation
through degradation of contaminants to non-toxic products to changing of pH and
concentration of chemical staffs and cost optimization. TiO 2 has been considered
one of the most effective ones because of its stability and some other advantages.
However, several efforts have been and are being followed to decrease the major
failure of TiO 2 to enhance usage in a huge area of solar light for more asked
applications. The original importance of sophistication of proper band gap and
chemistry of surface/interface addressed the required researches. The appropriate
studies are (i) usage of metals–non-metals having general suitable characters as
semiconductor, surface plasmon resonance, and so on, (ii) introduction of novel
composite compounds; (iii) study of the effect of dopants–additives–sensitizers;
(iv) finding the catalytic mechanism; (v) production of thin films of photocatalysts
within titania, alumina, stainless steel, and molecular sieves; (vi) enhancing the
effective surface area of photocatalyst; (vii) development of more sensitive
photocatalyst in natural sunlight against of fictional light; and (viii) applying of
diverse synthesis methods such as hydrothermal, co-precipitation, electrochemical,
sol–gel, and so on. Another important challenge regarded to designing of appropriate
photoreactor and the commercial concerns. Despite the great contents of mercantile
contaminants needing remedy, the running conditions of technology should not be
enough. However, at first an effective multiphasic impact of pollutant, oxygen, solar
light, and photocatalyst is required. In order to commercialize of scale implementation for reliable scale-up, the specification of eminent factors and simulation of a
reliable rate declaration are necessary. Investigations are still pursuing to improve
quantum yield and maximize the impact of substances and photons regarding
fluctuations in solar irradiation. Nonetheless, designing of photoreactors are
followed according to alternative and approximate kinetic statements. Main designs
of a photoreactor are performed for concentrating collector–reactor, compound
parabolic collector–reactor, and non-concentrating collector one (Blanco et al.
2009; Braham and Harris 2009; Spasiano et al. 2015). Of the related more routine
designs, compound parabolic collector–reactor includes more advantages about
utilizing both of beam and reactive components and is resulted as the most modern
9 Nanomaterials for the Photoremediation of Pollutants
307