It is clear that at this stage, all the products contain an aromatic ring; however, the
degradation continues with the cleavage of the ring and eventual mineralization of
the products [59, 67]. This is important because according to Feng et al. the toxicity
of these compounds can be reduced upon the mineralization of the aromatic intermediates, and they found out that the final oxidation products are carboxylic acids
such as pyruvic, acetic, formic, and oxalic which can be mineralized in 92% upon the
use of BDD with a photoelectro-Fenton method [66].
Similar results were obtained by Díaz et al. and Pourzamani et al. They showed
that the degradation of diclofenac and naproxen, respectively, began by generating
intermediates of reaction with an aromatic ring, which was further degraded upon
cleavage and formed carboxylic acids that were oxidized to carbon dioxide and
water [57, 60].
Finally, even though some materials show great removal of pharmaceuticals, it is
of utterly importance to mention that some of the research done in electrochemistry
is performed in artificial solutions where the concentration of the drug to be removed
is much higher than the actual concentration present in wastewater; therefore,
diffusion limitations can become greater and limit the efficiency of the process. In
consequence, some anodic oxidation has been coupled with other techniques such as
the use of ultrasound, UV light, or Fenton’s reagents, because they help either in
enhancing the mass transfer or producing additional hydroxyl radicals [66].
5 Conclusions and Perspectives
Adsorption, photocatalysis, and electrocatalysis, the most important treatment processes incorporating nanomaterials to remove NSAIDs from wastewater, have been
reviewed in this chapter. As it has been shown, the incorporation of nanomaterials in
these processes de facto increases their active surface area, resulting in improved
adsorption capacity and catalytic efficiency. As it is expected, these materials’
performance depends on their chemical nature. Properties such as hydrophilicity,
specificity toward certain molecules, stability, and ability to produce specific reactive species when exposed to UV-vis light or after a voltage is applied will always
rely on their chemical structure; therefore, different nanotechnologies can be applied
to tune these materials’ properties.
Physically and chemically activated carbon materials derived from biological
wastes have proven to be effective for removing selected NSAIDs in adsorption
methods even at very low concentrations and under different processing conditions.
Besides, the combination of these materials with magnetic nanoparticles is becoming
a simple alternative for the separation of adsorbents/catalysts by means of an
external magnet.
On the other hand, the nanostructured morphology of common bulk
photocatalysts or electrocatalysts are not only useful for increasing the active surface
area but for changing other physical properties such as band gap, electrical conductivity, and stability; in turn, all of these make them more efficient materials in terms
Nanotechnologies for Removal of Nonsteroidal Anti-inflammatory Drug from. . .
295
degradation continues with the cleavage of the ring and eventual mineralization of
the products [59, 67]. This is important because according to Feng et al. the toxicity
of these compounds can be reduced upon the mineralization of the aromatic intermediates, and they found out that the final oxidation products are carboxylic acids
such as pyruvic, acetic, formic, and oxalic which can be mineralized in 92% upon the
use of BDD with a photoelectro-Fenton method [66].
Similar results were obtained by Díaz et al. and Pourzamani et al. They showed
that the degradation of diclofenac and naproxen, respectively, began by generating
intermediates of reaction with an aromatic ring, which was further degraded upon
cleavage and formed carboxylic acids that were oxidized to carbon dioxide and
water [57, 60].
Finally, even though some materials show great removal of pharmaceuticals, it is
of utterly importance to mention that some of the research done in electrochemistry
is performed in artificial solutions where the concentration of the drug to be removed
is much higher than the actual concentration present in wastewater; therefore,
diffusion limitations can become greater and limit the efficiency of the process. In
consequence, some anodic oxidation has been coupled with other techniques such as
the use of ultrasound, UV light, or Fenton’s reagents, because they help either in
enhancing the mass transfer or producing additional hydroxyl radicals [66].
5 Conclusions and Perspectives
Adsorption, photocatalysis, and electrocatalysis, the most important treatment processes incorporating nanomaterials to remove NSAIDs from wastewater, have been
reviewed in this chapter. As it has been shown, the incorporation of nanomaterials in
these processes de facto increases their active surface area, resulting in improved
adsorption capacity and catalytic efficiency. As it is expected, these materials’
performance depends on their chemical nature. Properties such as hydrophilicity,
specificity toward certain molecules, stability, and ability to produce specific reactive species when exposed to UV-vis light or after a voltage is applied will always
rely on their chemical structure; therefore, different nanotechnologies can be applied
to tune these materials’ properties.
Physically and chemically activated carbon materials derived from biological
wastes have proven to be effective for removing selected NSAIDs in adsorption
methods even at very low concentrations and under different processing conditions.
Besides, the combination of these materials with magnetic nanoparticles is becoming
a simple alternative for the separation of adsorbents/catalysts by means of an
external magnet.
On the other hand, the nanostructured morphology of common bulk
photocatalysts or electrocatalysts are not only useful for increasing the active surface
area but for changing other physical properties such as band gap, electrical conductivity, and stability; in turn, all of these make them more efficient materials in terms
Nanotechnologies for Removal of Nonsteroidal Anti-inflammatory Drug from. . .
295