## 3 Results and Discussion
### Retention of 2,4-DCFA by Composite Beads in Adsorption/Oxidation Processes  
The adsorption tests were performed using the whole bead, which led to a difference between the amount of sample of 40.0 \(\pm\) 1.0 mg. Even though the beads were thoroughly washed to remove the solvent (Table 1), some residual alcohol remained in the more confined pore structures of beads and leached out during the 24 h adsorption interval, interfering with the TOC measurement for 2,4-DCFA quantification. As observed from the results centralized in Table 4, the supernatants of 2,4-DCFA solutions after adsorption show higher values of TOC compared to the initial value of 46.35 mg C/L (corresponding to the solution of 100 mg 2,4-DCFA/L), except for sample 3-RM. Another interference in TOC measurement for RM-based based composite beads may be associated with the small (5.7%) but existing amount of CO\({}_{2}\) in the RM, which may be released at low pH values. Nevertheless, the results may be interpreted qualitatively, and aside from the potential CO\({}_{2}\) release, 3-RM seems to be the only system capable of absorbing at least 9.7% 2,4-DCFA from the initial solution. This is why the following oxidation trials were performed only for this system and compared to its reference, 3-Ref, as well as to the values obtained for RM alone. The results of the oxidation trial are summarized in Table 5, in which case a similar amount of adsorbent (40.0 \(\pm\) 0.2 mg) was used. In support of the selection of the 3-RM system, it can be mentioned that the increase in carboxylic groups in the precursor copolymer (resulting from the use of higher AA ration) contributes to the particular performance of 3-RM. If we evaluate the chemical structure of AA and AN monomer units and that of 2,4-DCFA, it is more likely that the cyano groups in AN interact with the carboxylic groups in 2,4-DCFA through hydrogen bonds. Therefore, to facilitate the access of 2,4-DCFA to the cyano groups, a more hydrophilic environment is needed to favor the diffusion processes. The increase in AA contributes to the creation of this environment [80,81], especially when using 20% (the case of 3-RM and 3-Ref). On the other hand, if the content of AA is increased over 20%, the copolymer becomes too \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Sample** & \begin{tabular}{c} **BET Surface Area** \\ **(m\({}^{2}\)g\({}^{-1}\))** \\ \end{tabular} & \begin{tabular}{c} **Pore Surface Area** \\ **(BJH) (m\({}^{2}\)g\({}^{-1}\))** \\ \end{tabular} & \
\begin{tabular}{c} **Mean Pore Diameter** \\ **(BJH) (nm)** \\ \end{tabular} &
\begin{tabular}{c} **Mean Pore Volume (BJH)** \\ **(cm\({}^{3}\)g\({}^{-1}\))** \\ \end{tabular} \\ \hline
1-Ref & 56.72 & 65.51 & 3.47 & 0.0277 \\
1-RM & 7.07 & 5.99 & 3.17 & 0.0113 \\
2-Ref & 41.79 & 66.59 & 4.54 & 0.0545 \\
2-RM & 2.74 & 18.60 & 4.54 & 0.0150 \\
3-Ref & 1.15 & 3.09 & 4.54 & 0.0037 \\
3-RM & 2.18 & 3.47 & 4.54 & 0.0070 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Parameters of samples determined by N\({}_{2}\) porosimetry. hydrophilic to be used with success for the wet phase inversion process [80]. Another relevant study [81] highlighted that even methacrylic acid, which is less water-soluble than AA, should be used in ratios of maximum 20% relative to AN for achieving a good adsorption of analytes. Following the oxidation assays, a clear decrease in the TOC value is observed for both 3-RM and the reference, indicating that 2_A_-DCFA is retained quantitatively in the copolymer beads (Table 5). Another exciting value of TOC is attained for RM alone, which now suggests that RM may release CO\({}_{2}\) upon adsorption/oxidation. The TOC value for 3-RM calculated against the initial TOC value after oxidation of 2_A_-DPCA is close to that obtained in the previous adsorption test (12.8% vs. 9.7%), confirming the potential adsorbent character of 3-RM.