## 3 Results and Discussion
### Swelling Test  
For this test, uncrosslinked CS beads were also obtained to evaluate the swelling capacity and the cross-linking effect with GLA. The swelling of the beads was measured in a neutral aqueous medium and an acid medium (0.1 M HCl) in duplicate. Table 7 shows the results of swelling of the synthesized cross-linking chitosan beads (%). The swelling test studies the porous expansion of the synthesized beads, and although it is related to the adsorption capacity, it is not the variable that affects it to a greater extent, such as the pH and the initial concentration of the dye [13; 37]. The swelling mechanism involves the adsorption of water molecules through hydrogen bonds by the polar groups of the CS. Table 7 shows that the uncrosslinked CS beads show the highest swelling compared to the synthesized beads. However, CS is not stable and eventually solubilizes in the acidic media. On the other hand, the swelling decreases considerably with GLA incorporation. An alteration occurs throughout the entire CS structure during the cross-linking process, significantly affecting its adsorption capacity [38]. The decrease in the swelling degree is explained by the existence of fewer nitrogen atoms available for water adsorption since GLA chemically reacts with CS to form the mine-type covalent bond [39]. The effect of TiO\({}_{2}\) nanoparticles on swelling agrees with the previously reported by [PERSON] et al. [40], where the addition of zinc oxide (ZnO) nanoparticles to CS hydrogels decreases the swelling capacity. This swelling decreasing can be attributed to the metal oxide nanoparticles, which restrict the expansion of the polymeric chains by \"strong knot tightening\" through chelation with some amino and hydroxyl groups of CS. The study of [PERSON] et al. [14] indicates that there is a decrease (from 22.54% to 14.49%) in NH\({}_{2}\) groups of CS for two CS-TiO\({}_{2}\)-GLA bead systems (25 and 50 wt.%) due to the interaction between the titanium atom of the nanoparticles (acting as Lewis acid) and the \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Run**} & \multirow{2}{*}{**Initial Dye Concentration**} & \multicolumn{2}{c}{**Removal Efficiency (\%)**} \\ \cline{3-4}  & & **CS-TiO\({}_{2}\)-GLA** & **CS-GO-TiO\({}_{2}\)-GLA** \\ \hline
6 & 45 & 7.0 & 17.3 & 96.7 \\
13 & 15 & 7.0 & 54.3 & 99.3 \\
15 & 45 & 3.0 & 100.0 & 100.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of the removal efficiency of dye between the two adsorbent systems prepared (Amount of TiO\({}_{2}\) for all beads was 300 mg and 3 wt.% GO relative to TiO\({}_{2}\)). \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Beads**} & \multicolumn{2}{c}{**Swelling (\%)**} \\ \cline{2-3}  & **Distilled Water** & **HCl 0.1 M** \\ \hline CS & 139.8 & Soluble \\ CS-GLA & 39.5 & 63.0 \\ CS-TiO\({}_{2}\)-GLA & 36.2 & 74.3 \\ CS-GO-TiO\({}_{2}\)-GLA & 33.7 & 44.9 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Swelling percentages of the nanocomposite beads. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**GO (wt.\% Relative to TiO\({}_{2}\))**} & **Run CCD** & **Initial Dye Concentration (mg L\({}^{-1}\))** & **pH** & **Removal Efficiency (\%)** \\ \hline
1\% & 6 & 45 & 7.0 & 83.5 \\
1\% & 13 & 15 & 7.0 & 98.5 \\
15 & 45 & 3.0 & 100.0 \\
6 & 45 & 7.0 & 96.7 \\
3\% & 13 & 15 & 7.0 & 99.3 \\
15 & 45 & 3.0 & 100.0 \\
10\% & 6 & 45 & 7.0 & 91.3 \\
15 & 15 & 7.0 & 98.2 \\
15 & 45 & 3.0 & 99.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: GO effect in the removal efficiency of FD&C Red 40 dye. free electron pair of the CS nitrogen (Lewis base). In the present work, 10 wt.% TiO\({}_{2}\) was used and could be assumed a decrease in the amount of NH\({}_{2}\) groups available. By adding the GO to the CS-TiO\({}_{2}\)-GLA system, the degree of swelling decreased only by 2.5% (Table 7), probably due to an electrostatic interaction between GO and TiO\({}_{2}\), decreasing its capacity to capture water molecules [41], so the change in porous expansion is minimal.