## 3 Results and Discussion
### Sorption Abilities Tests
#### 3.4.2 The Pharmaceuticals Sorption  
The above considerations also justified the obtained results of drug sorption on the tested polymers. Salicylic acid and aspirin are acidic compounds (pKa in the range 2.8-3.5) that are well soluble in water. Their recoveries do not exceed 10% because in their aqueous solution under the conditions of the experiment, the dominant forms were the dissociated ones. For salicylic acid, the highest recovery value (ca. 35%) was recorded for Lo-DVB, i.e., the polymer with the most acidic surface. The ionized salicylic acid in contact with the strongly acidic surface of the Lo-DVB polymer began to turn into undissociated species, the sorption of which was more effective. This description was in line with the previous one regarding the sorption of 2,4,6-TChP. Aspirin, which is an acetyl derivative of salicylic acid, is slightly more soluble in water and has a less acidic character, which justified the lower recoveries and a less pronounced influence of the acidity of the polymer surface on the obtained recovery results. A similar observation was also reported by [PERSON] et al. [34]. Ampicillin in its structure, apart from the acidic carboxyl group, also possessed amine and amide groups, which gave it a basic character. The polarized nature of these chemical bonds caused the hydrophilic character of the ampicillin to be predominant, which was confirmed by one of the lowest log Ps and its good solubility in water. Moreover, its large molecule was the most complex in terms of spatial structure compared to the other test compounds used in this study. All these features undoubtedly influenced its interaction with the polymers. Among the selected pharmaceuticals, ibuprofen and paracetamol had the highest affinity to the tested polymers. For ibuprofen and paracetamol, the recoveries were in the range of 27-70% and 5-40%, respectively. When analyzing the results obtained for paracetamol, it should be stated that higher values of recovery were obtained for terpene-based polymers with highly developed porosity and were much lower for the oil-based ones with much lower specific surfaces. The Lo-DVB and Ro-DVB polymers had similar porous structure parameters but the recovery for the former, which surface was twice richer in acid functional groups, was three times higher than that for the latter. Paracetamol in its structure had two functional groups attached to the aromatic ring: a hydroxyl and an amide. There were strongly negative electrostatic potentials accumulated in the O-H and C=O groups, while in the NH group, a positive potential was localized [30]. The presence of these oxygen functionalities gave this molecule a hydrophilic character (logP, water), which resulted in its lower affinity towards the polymers. On the other hand, the presence of a partial positive charge on the paracetamol molecule favored its stronger interaction with acidic surfaces, as is schematically shown in Figure 10. This effect is clearly visible when comparing the Lo-DVB and Ro-DVB recoveries. The values of paracetamol recoveries for terpene-based polymers differed very little. However, it should be noted that this difference was the result of two independent factors--surface porosity and acidity. Namely, C-DVB had a smaller specific surface area, but about  
Figure 10: Scheme of possible interactions between a paracetamol molecule and an acid functional group on the polymer surface. twice more acid groups than L-DVB with a larger surface area. The paracetamol OH and CONH groups formed associations with the functionalities of the polymer using the other electrostatic potentials accumulated around these moieties. The specific interactions of paracetamol with more numerous acidic groups of C-DVB, compensated for the loss of uptake due to the lower, by about 100 m\({}^{2}\)/g, specific surface area. For this reason, it was finally observed that the sorption effect was almost identical for both materials.