development of nanomaterials to eliminate NSAIDs from water in the fields of
adsorption, photocatalysis, and electrocatalysis, which have been in the spot of
environmental research for these pharmaceutical wastewater treatments.
2 Nanomaterials for NSAIDs Adsorption
Recently, Mlunguza et al. reviewed the use of different adsorbent materials, which
can become an efficient removal strategy for NSAIDs present in water effluents
[12]. Among the systems reviewed, we can find activated carbon, ligninolytic
enzymes, graphene-based adsorbents, molecularly imprinted polymers, electrochemical methods, sonochemical processes, and photocatalytic degradation.
Nanomaterials are becoming an important class of adsorbing materials due to their
small size, large active surface area, catalytic properties, and easy tunability through
chemical functionalization of their surfaces. These so-called “nanoadsorbents” may
be capable of removing the new emerging pollutants selectively, even at very low
concentrations (μg/L) and under different conditions of pH, temperature, and wastewater composition [13]. Here, we will discuss and analyze some specific features,
advantages, and limitations of selected examples of adsorbent materials recently
reported in the literature.
Graphene has been revisited as a versatile nanomaterial that can be used as
photocatalyst, disinfectant, and, due to its large surface area, a potentially useful
adsorbent in water treatment technologies [14]. The efficiency of removal of ibuprofen, ketoprofen, naproxen, and sodium salt of diclofenac from an aqueous model
and a real solution was investigated by Al-Khateeb et al. using high surface area
graphene (HSAG) (Fig. 2a). They evaluated different operational parameters that
may affect the adsorption process including solution pH, temperature, and adsorption time. Kinetic and thermodynamic parameters were also determined in order to
understand the adsorption mechanism. Characterization of the HSAG showed that it
was conformed by layered nanoplatelets (average thickness of 5.0 nm) and surface
area of 677.5 m
2 g
À1 . The material was able to remove most of the studied NSAIDs
after a few minutes using 10 mg of the HSAG at room temperature, with adsorption
capacities of 11.9 mg/g (ibuprofen), 16.6 mg/g (ketoprofen), 17.8 mg/g (naproxen),
and 19.3 mg/g (diclofenac sodium salt). Thermodynamically, the adsorption process
was spontaneous, endothermic, and temperature-dependent (the higher temperature,
the larger the adsorption capacities). When tested in a real water sample, the results
showed a high removal efficiency for the mentioned NSAIDs [15]. Focusing on
other type of carbon-based nanoadsorbent, Ahmed reviewed the performance of
different types of activated carbons (ACs, Fig. 2b) as adsorbents for the water
remotion of ibuprofen, ketoprofen, naproxen, and diclofenac [16]. The ACs were
prepared by physical and chemical activation of lignocellulosic biomass and/or agroindustrial wastes. In general, ACs show better adsorption properties than zeolites,
graphene-based adsorbents, and clays. The maximum adsorption capacities obtained
from Langmuir isotherms for these drugs were of 417, 25, 290, and 372 mg/g for
280
M. Cerro-Lopez et al.
adsorption, photocatalysis, and electrocatalysis, which have been in the spot of
environmental research for these pharmaceutical wastewater treatments.
2 Nanomaterials for NSAIDs Adsorption
Recently, Mlunguza et al. reviewed the use of different adsorbent materials, which
can become an efficient removal strategy for NSAIDs present in water effluents
[12]. Among the systems reviewed, we can find activated carbon, ligninolytic
enzymes, graphene-based adsorbents, molecularly imprinted polymers, electrochemical methods, sonochemical processes, and photocatalytic degradation.
Nanomaterials are becoming an important class of adsorbing materials due to their
small size, large active surface area, catalytic properties, and easy tunability through
chemical functionalization of their surfaces. These so-called “nanoadsorbents” may
be capable of removing the new emerging pollutants selectively, even at very low
concentrations (μg/L) and under different conditions of pH, temperature, and wastewater composition [13]. Here, we will discuss and analyze some specific features,
advantages, and limitations of selected examples of adsorbent materials recently
reported in the literature.
Graphene has been revisited as a versatile nanomaterial that can be used as
photocatalyst, disinfectant, and, due to its large surface area, a potentially useful
adsorbent in water treatment technologies [14]. The efficiency of removal of ibuprofen, ketoprofen, naproxen, and sodium salt of diclofenac from an aqueous model
and a real solution was investigated by Al-Khateeb et al. using high surface area
graphene (HSAG) (Fig. 2a). They evaluated different operational parameters that
may affect the adsorption process including solution pH, temperature, and adsorption time. Kinetic and thermodynamic parameters were also determined in order to
understand the adsorption mechanism. Characterization of the HSAG showed that it
was conformed by layered nanoplatelets (average thickness of 5.0 nm) and surface
area of 677.5 m
2 g
À1 . The material was able to remove most of the studied NSAIDs
after a few minutes using 10 mg of the HSAG at room temperature, with adsorption
capacities of 11.9 mg/g (ibuprofen), 16.6 mg/g (ketoprofen), 17.8 mg/g (naproxen),
and 19.3 mg/g (diclofenac sodium salt). Thermodynamically, the adsorption process
was spontaneous, endothermic, and temperature-dependent (the higher temperature,
the larger the adsorption capacities). When tested in a real water sample, the results
showed a high removal efficiency for the mentioned NSAIDs [15]. Focusing on
other type of carbon-based nanoadsorbent, Ahmed reviewed the performance of
different types of activated carbons (ACs, Fig. 2b) as adsorbents for the water
remotion of ibuprofen, ketoprofen, naproxen, and diclofenac [16]. The ACs were
prepared by physical and chemical activation of lignocellulosic biomass and/or agroindustrial wastes. In general, ACs show better adsorption properties than zeolites,
graphene-based adsorbents, and clays. The maximum adsorption capacities obtained
from Langmuir isotherms for these drugs were of 417, 25, 290, and 372 mg/g for
280
M. Cerro-Lopez et al.