## 4 Conclusions  
In this article, we obtained styrene-divinylbenzene copolymers functionalized with aminobenzic acid groups by polymer-analogous reactions. The obtained products, PAB1, PAB2, and PAB3, were characterized by a wide range of methods: FTIR, thermogravimetric analysis, and EDX, SEM, BET, and BJH analysis, and were tested by extensive kinetic and thermodynamic studies on the adsorption of antibiotics (tetracycline, sulfamethoxazole, and amoxicillin) from aqueous solutions. From the data presented in our article, a number of conclusions can be drawn regarding the behaviors of the functionalized styrene-divinylbenzene copolymers as adsorbents:  
It was found that all the polymeric adsorbents modified by functionalization with aminobenzic acid groups could be used in the adsorption processes of some antibiotics from aqueous solutions. They were tested in the removal of the sulfamethoxazole and tetracycline. Amoxicillin adsorption was also attempted, but it did not produce in positive results. The adsorption capacity of the tested polymer adsorbents depended on the degree of crosslinking and the percentage of divinylbenzene in their structure, which affected the porosity, total surface area, pore volume, and pore distribution. The efficiency of the polymer adsorbents was found to increase in the following order: PAB1 < PAB2 < PAB3. This was in agreement with the increase in the cross-linking degrees and porosity. The most effective adsorbent behavior for the removal of antibiotics was demonstrated by the PAB3 polymer adsorbent. The adsorption capacity of the functionalized polymeric matrices depended on the nature and structure of the adsorbed antibiotic. The sulfamethoxazole and tetracyclinewere well adsorbed on all three adsorbents. In ascending order of adsorption capacity, antibiotics are placed in the sequence: sulfamethoxazole < tetracycline. The adsorption process was rather fast: in the first 3-4 h, at least 80% of the maximum adsorption capacity was reached (see Figures 6-8). The kinetic studies of the sulfamethoxazole and tetracycline removal by adsorption on the studied polymeric adsorbents indicated that the process is best described by a pseudo-second-order kinetic model (Ho-McKay). The increase in the operational 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 indicated that the adsorption process was most likely exothermic. The analysis of the adsorption isotherms indicated that the solid adsorbents had rather heterogeneous surfaces and suggested a probable hybrid adsorption mechanism and a _twoorable_ adsorption process. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/molecules27092894/s1](https://www.mdpi.com/article/10.3390/molecules27092894/s1)]([https://www.mdpi.com/article/10.3390/molecules27092894/s1](https://www.mdpi.com/article/10.3390/molecules27092894/s1)). Figure S1: Chemical structures of the adsorbates. Table S1: Kinetic parameters of pseudo-first-order (PFO) and pseudo-second-order (PSO) for the adsorption of sulfamethoxazole and tetracycline on PAB 1, PAB 2, and PAB 3 polymeric adsorbents. Table S2: Experimental equilibrium adsorption data. Table S3: Parameters of Langmuir, Freundlich, Sips, and Redlich-Peterson adsorption isotherms in the adsorption of sulfamethoxazole. Table S4: Separation factors RL for sulfamethoxazole adsorption onto PAB1, PAB2, and PAB3 adsorbents. Table S5: Parameters of Langmuir, Freundlich, Sips, and Redlich-Peterson adsorption isotherms in the adsorption of tetracycline. Coordination of the research project, C.-M.D. and E.S.D. ; coordination and performance of the experimental works, R.A.; methodology, A.P. ; product characterization and analysis, M.I. ; formal analysis, A.P. ; writing--original draft preparation, C.-M.D., R.A. and A.P. ; writing--review and editing, C.-M.D. and E.S.D.