## 2 Results and Discussion
### Adsorption Experiment
#### 2.9.2 Adsorption Isotherms  
The isotherm plots obtained from the CFA adsorption onto the WMS and NR/WMS materials are compared in Figure 10 and Figure S3. The data were analyzed with the Langmuir and Freundlich mathematical expressions to postulate the model of CFA adsorption onto the pristine and functionalized materials. The CFA adsorption capacity observed for these adsorbents was ranked in the following descending order: NR/WMS-0.05 > NR/WMS-0.10 > NR/WMS-0.15 > WMS-0.10 > NR/WMS > WMS. The calculated parameters and R\({}^{2}\) for each adsorbent are shown in Table 4. The isotherms of CFA adsorption on the amino-functionalized WMS and NR/WMS materials properly fitted with Langmuir models, while the Freundlich model was more suitable for the adsorption over the pristine WMS and NR/WMS materials as judged by the R\({}^{2}\) values and data modeling approaches (Figure S3). The previous study revealed that the adsorption of CFA onto the amino-functionalized mesoporous silica materials was best described with the Langmuir adsorption model [3; 17]. In our case, the isotherm study suggested that the CFA adsorption onto the surface of pure silica WMS and NR/WMS nanocomposites without and with the aminopropyl groups proceeded via a combination of different interaction forces [3; 18; 38]. The silanol groups mainly provided the hydrogen-bonding interaction, while the amino-functional groups offered both a hydrogen-bonding interaction and electrostatic force with the CFA molecules. According to [PERSON], the amine-functionalized SBA-15 enhanced the adsorption capacity of pharmaceutical residue molecules in aqueous solution due to both a hydrogen-bonding interaction and electrostatic force [40]. The introduction of a rubber phase into the mesostructured silica inserted a weak hydrophobic interaction via the aromatic moieties of the CFA molecules. [PERSON] et al. reported that the polyamidoamine/silica (PAMAM/SiO\({}_{2}\)) adsorbent exhibited a higher adsorption capacity of CFA compared to pure SiO\({}_{2}\) adsorbent due to its hydrophobicity and amine-functionalized group [41]. Therefore, the presence of both the NR and aminopropyl groups in the NR/WMS-NH\({}_{2}\) materials promoted not only the adsorption kinetics by reducing the competitive adsorption of H\({}_{2}\)O, but also molecular interactions with the CFA molecules, resulting in the enhanced adsorption performance.  
\begin{table}
\begin{tabular}{l c c c|c c c} \hline \hline  & \multicolumn{3}{c}{**[PERSON]**} & \multicolumn{3}{c}{**[PERSON]**} \\ \cline{2-7}
**Adsorbent** & \(k_{\text{L}}\) & \(q_{\text{m}}\) & \(R^{2}\) & \(n\) & \(k_{\text{F}}\) & \(R^{2}\) \\  & (**L mg\({}^{-1}\))** & (**mg g\({}^{-1}\))** & & & & \\ \hline WMS & 0.008 & 1.81 & 0.996 & 1.13 & 0.017 & 0.999 \\ WMS-0.10 & 0.016 & 3.73 & 0.993 & 1.38 & 0.103 & 0.976 \\ NR/WMS & 0.006 & 3.13 & 0.969 & 0.84 & 0.012 & 0.999 \\ NR/WMS-0.05 & 0.026 & 6.29 & 0.999 & 1.55 & 0.305 & 0.993 \\ NR/WMS-0.10 & 0.022 & 5.66 & 0.998 & 1.50 & 0.230 & 0.993 \\ NR/WMS-0.15 & 0.020 & 4.30 & 0.997 & 1.44 & 0.149 & 0.991 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Isotherm parameters of CFA adsorption onto the adsorbent.