## 3 Results and Discussion
### Sorption Abilities Tests
#### 3.4.1 The Sorption of the Phenols Mixture  
The upper panels of Figure 8 present the results of the sorption of the phenolic compounds on the above specified materials. Figure 8: _Cont_. In the first pair of polymers, 2,4-DChP showed the highest affinity to the C-DVB and L-DVB surfaces. This compound also achieved the highest recoveries even for sample volumes as large as 500 mL. A slight increase in recovery in this range of sample volumes may be caused by the longer interaction time of the sorbent with the solution. At a volume of 600 mL, a decrease in the recovery value was observed; thus, a breakthrough volume for this compound had been reached. 2-ChP and 2,4,6-TChP initially showed similar recoveries of about 50-80% for small sample volumes, but as the sample volume increased, the recoveries for the former compound gradually decreased and for the latter, they increased. This phenomenon can be explained in the following way: as the volume of the sample increased, the interaction time of the sorbent with the solution became longer, and this in turn may have led to a situation in which the previously adsorbed 2-ChP was replaced by 2,4,6-TChP, which interacted more strongly with the polymer surface. The process of sorption of aromatic compounds at the polymer-solution interface showed some analogies to the extraction process in the octanol-water system; therefore, the factors of lipophilic and hydrophilic properties, such as the octanol-water partition coefficient and water solubility, may be useful for explaining some dependencies related to the course of processes that took place during the solid phase extraction [57]. Comparing the logP and s\({}_{\text{water}}\) data (Table 6) allowed for an explanation of why the molecules of 2-ChP could be replaced by those of 2,4,6-TChP. The higher logP value and lower solubility in water of 2,4,6-trichlorophenol indicated that it was more lipophilic than 2-ChP; therefore, its interaction with the polymer surface was stronger. On the other hand, the recoveries of 2,4,6-TChP were up to 25% lower than those obtained for 2,4-DChP. Taken together, the logP values for the two compounds suggested that 2,4,6-TChP should be adsorbed better than 2,4-DChP, but the obtained results showed an inverse relationship. In order to understand why this was so, the values of the acid dissociation constants pKa (Table 6) should be taken into account. Under the experimental conditions, the tested solutions had a slightly acid to neutral pH. In such an environment, the pKa of 2,4,6-TChP was close to the pH value, and therefore, dissociated molecules were also present in the solution. Excluding the possibility of electrostatic interactions, their interactions with the sorbent were weaker than these of the undissolved molecules, which in turn reduced the efficiency of the sorption process. Phenol is the compound with the lowest affinity for both polymers. The maximum recoveries of this compound were 40 and 20% for C-DVB and L-DVB, respectively, and they decreased gradually with increasing sample volume. This was a consequence of good water solubility and the relatively low lipophilic character of phenol. Figure 8: SPE results for C-DVB, L-DVB, Lo-DVB, and Ro-DVB. In the case of the second pair of sorbents (Lo-DVB and Ro-DVB), the observed relationships were almost the same as those for the terpene-based polymers. However, due to the oil-based polymers having around five times lower specific surface areas, the effectiveness of these materials was slightly lower. Additionally, attention should be paid to the PSD of the discussed materials. This pair of polymers had a much larger proportion of wider mesopores and macropores in their structure, and narrow-width pores made up a small fraction of the total pore volume, especially in the case of Lo-DVB. For this reason, although both polymers possessed quite similar values of the porous structure parameters, higher recoveries were obtained for Ro-DVB, which had a greater portion of pores with widths below 6 nm than the polymer Lo-DVB.