## 2 Results and Discussion
### Adsorption Characterization  
In the graphical representations, we mostly present the data for the best-performing adsorbent, PAB3.  
The adsorption capacity onto the polymeric adsorbents was calculated using Equation (1):  
\[q_{e}=\frac{V(C_{i}-C_{e})}{m} \tag{1}\]  
where \(V\) is the volume of solution (L), m is the mass of the dry adsorbent (g), and \(C_{i}\) and \(C_{e}\) (mM/L) are the initial and equilibrium concentrations of the sulfamethoxazole and tetracycline, respectively.  
The comparison of the evolution with the time of the adsorption process on the adsorbent PAB3 is presented in Figures 6 and 7.  
As can be seen from Figures 6 and 7, the adsorption process was fast: at least 80% of the maximum adsorption capacity (equilibrium adsorption capacity) was attained in 4 hrs. Similar behavior was observed with the adsorbents PAB1 and PAB2.  
\begin{table}
\begin{tabular}{c c c} \hline
**Polymeric Adsorbent** & **Surface Area, m\({}^{2}\)/g** & **Total Pore Volume, cm\({}^{3}\)/g** \\ \hline PAB1 & 20.14 & \(2.44\times 10^{-2}\), for pores with \(\phi<45.7\) nm \\ PAB2 & 27.89 & \(4.11\times 10^{-2}\), for pores with \(\phi<47.2\) nm \\ PAB3 & 34.56 & \(5.68\times 10^{-2}\), for pores with \(\phi<47.6\) nm \\ \hline \end{tabular}
\end{table}
Table 2: BET analysis of styrene–divinylbenzene copolymers functionalized with aminobenz-zoic groups.  
Figure 6: Evolution of the % of the equilibrium adsorption capacity and adsorption capacity versus time for the adsorption of sulfamethoxazole on the adsorbent PAB3.  
A comparison of the performances of the adsorbents PAB1, PAB2, and PAB3 in the adsorption of the sulfamethoxazole and tetracycline, respectively, at four temperatures (298 K, 308 K, 313 K and 318 K), for an initial concentration of adsorbate solution of 3 mM/L, is presented in Figure 8.  
As can be seen, all the adsorbents under study were effective in the adsorption of the sulfamethoxazole and tetracycline. The performances were ranked in the following order:  
\[\text{PAB1}<\text{PAB2}<\text{PAB3}\]  
The performance of the adsorbents can be correlated with the morphology and textural properties of the functionalized copolymers. The best performance was observed with the macroporous adsorbent PAB3, which had the largest surface area, total pore volume, and mean pore volume (see Table 2). The equilibrium adsorption capacity was also dependent on the chemical nature of the adsorbate, with the tetracycline being better adsorbed in  
Figure 8: Equilibrium adsorption capacity on the studied adsorbents for an initial adsorbate concentration of 3 mM/L.  
Figure 7: Evolution of the % of the equilibrium adsorption capacity and adsorption capacity versus time for the adsorption of tetracycline on the adsorbent PAB3.  
comparison with the sulfamethoxazole. As can be observed in Figure 9, increasing the operation temperature had a rather minor effect, which suggests that the adsorption process was most likely thermodynamically controlled and not kinetically controlled. The slight decrease in the equilibrium adsorption capacity versus the temperature indicates that the adsorption process was most likely exothermic.