3618
R.N. Coimbra et al.
25
0 1 2 3 4 5 6 7 8 9 10
(a)
(b)
20
15
10
Experimental data
Experimental data Freundlich Langmuir Sips
Freundlich
5
Langmuir
0
0
20
40
60
80
100
0
20
40
60
80
100
C e (μg L
-1 )
C e (μg L
-1 )
16
16
(d)
(c)
14
14
12
12
10
10
8
8
6
6
Experimental data Freundlich Langmuir Sips
Experimental data Freundlich Langmuir Sips
4
4
2
2
0
0
0
20
40
60
80
100
0
20
40
60
80
100
C e (μg L
-1 )
C e (μg L
-1 )
Figure 4 Equilibrium results on the removal of (a) diclofenac, (b) salicylic acid, (c) ibuprofen, and (d) acetaminophen from ultrapure water by adsorption onto PS800-150. Experimental results are shown together with fittings to the Freundlich, to the Langmuir and to the Sips isotherm models. Note: error bars stand for standard deviation of three experimental replications.
microorganisms in wastewater. In fact, Combarros et al. (2014) proved that the formation of bacterial biofilm on the sur- face of a commercial activated carbon increased the adsorptive removal of salicylic acid from water. In fact, it is possible that the synergetic microorganism action may have compensated the competitive effect of organic matter so that the removal capacity remains the same when using the produced charcoal for the removal of diclofenac, salicylic acid, ibuprofen and acet- aminophen. It must be highlighted that, it was verified in this work that the pharmaceuticals concentration in controls (ultra- pure or STP secondary effluent, in the absence of charcoal) remained constant throughout the duration of all the experiments. Unfortunately, no other than the here referred works have been found in the literature on the comparative kinetics or iso- therms in ultrapure and wastewater for the adsorption of phar- maceuticals. Therefore, it is not possible to further contrast our findings with results by other authors and with other adsorbent materials. From our point of view, this sort of study is essential for the application of any adsorbent in the tertiary treatment of wastewater.
Our results differ from those by Sotelo et al. (2012), who determined the adsorption isotherms of diclofenac and isopro- turon using three carbonaceous materials (activated carbon, multiwalled carbon nanotubes and carbon nanofibers), found that the single adsorption capacity of these drugs was higher in ultrapure water than in real wastewater. Similarly, Kovalova et al. (2013) determined the adsorption isotherm and batch kinetic data using two powdered activated carbons to assess the removal of the pharmaceuticals 5-fluorouracil (5- Fu) and cytarabine (CytR) from ultrapure water and from a wastewater treatment plant effluent. These authors (Sotelo et al., 2012; Kovalova et al., 2013) found that the presence of organic matter in wastewater lowered the pharmaceuticals adsorption uptake. Using natural organic matter (NOM), Saravia and Frimmel (2008) showed that its presence slightly reduced the adsorption of pharmaceuticals, namely carba- mazepine, clofibric, diclofenac, and iohexol on activated car- bon. On the contrary, Me´ ndez-Dı´ az et al. (2012) found that an increased adsorption capacity of phthalic acid (PA) from wastewater than from ultrapure water occurred onto two differ- ent activated carbons, which was attributed to the action of
Made with FlippingBook Digital Publishing Software