## 3 Results and Discussion
### Comparison with Other Carbon/TiO\({}_{2}\) Composites  
A comparison of different carbon nanomaterials in composites with TiO\({}_{2}\) for the photocatalytic degradation of MO is presented in Table 3. A direct comparison is difficult due to differences in the experimental conditions used by the different workers. In Table 3, different composites of TiO\({}_{2}\)/carbon nanomaterials with different sources of carbon are presented: carbon nanofibers [CNFs] of cellulose origin (TiO\({}_{2}\)/CNF), graphitic carbon nitride (g-C\({}_{3}\)N\({}_{4}\): TiO\({}_{2}\)/g-C\({}_{3}\)N\({}_{4}\)), nitrogen-doped graphene quantum dots (N-GQDs) [N-GQD/TiO\({}_{2}\)], carbon quantum dots (CQDs) [TiO\({}_{2}\)/CQD], multiwall-carbon nanotubes (MWCNTs) [MWCNT/TiO\({}_{2}\)], and OLNCs [TiO\({}_{2}\)/OLNC].  
In all cases, the combination of carbon/TiO\({}_{2}\) has proven effective in the removal of MO at low initial concentrations (10 to 40 mg/L). The adsorption of MO to the photocatalyst's surface is important for the rapid degradation of the dye. For the selected composites, adsorption of the dye by the TiO\({}_{2}\) alone was lower than in the composite materials. This was attributed to the active sites responsible for dye adsorption. This resulted in a synergistic removal pathway of the dye with the dye adsorbed on the surface of the photocatalyst through carbon material. This was followed by the degradation of the dye molecules through the TiO\({}_{2}\). The synthesized composites of TiO\({}_{2}\)/OLNC proved to be comparable with other carbon/TiO\({}_{2}\)-based photocatalysts, as it demonstrates 99.9% degradation of MO at 120 min--significantly higher than all the presented composites. However, the TiO\({}_{2}\)/CNF and the MWCNT/TiO\({}_{2}\) showed fewer reaction times of 30 min and 90 min, respectively, with the TiO\({}_{2}\)/CNF having the lowest volume of MO solution (20 mL). The composites with the lowest degradation were the TiO\({}_{2}\)/CQD and TiO\({}_{2}\)/g-C\({}_{3}\)N\({}_{4}\) at 39.1% and 55%, respectively. This could be due to the generally low surface functional groups [33]. Therefore, along with a simple synthesis method of flame pyrolysis of waste cooking oil for making OLNCs the TiO\({}_{2}\)/OLNC composites show potential in the photocatalytic degradation of MO.  
Figure 11: Schematic representation of MO degradation using the OLNCs/TiO\({}_{2}\) photocatalyst.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Photocatalyst** & **Carbon Source** & **C\({}_{\textbf{O}}\) (mg/L)** & **Degradation (\%)** & **Time (Min)** & **Volume (mL)** & **Reference** \\ \hline TiO\({}_{2}\)/CNF & Nanocellose & 40 & 99.72 & 30 & 20 & [34] \\ TiO\({}_{2}\)/g-C\({}_{3}\)N\({}_{4}\) & g-C\({}_{3}\)N\({}_{4}\) & 10 & 55 & 180 & 100 & [35] \\ N-GQD/TiO\({}_{2}\) & N-GQDs & 10 & 95 & 120 & 50 & [36] \\ TiO\({}_{2}\)/CQD & CQDs & 10 & 39.1 & 120 & 100 & [37] \\ MWCNT/TiO\({}_{2}\) & MWCNTs & 15 & 97.4 & 90 & 150 & [38] \\ TiO\({}_{2}\)/MC & RF & 100 & 89 & 75 & \(\ast\) & [39] \\ MgO/TiO\({}_{2}\)/biochar & Biochar & 20 & 97.48 & 60 & 40 & [40] \\ TiO\({}_{2}\)/OLNC & OLNCs & 10 & 99.9 & 120 & 100 & This study \\ \hline \hline \end{tabular}  
* No data provided.  
\end{table}
Table 3: Comparison of different carbon/TiO\({}_{2}\) photocatalysts for MO degradation.