## 4 Conclusions  
A batch of FS-FT (0 g) catalysts was synthesized using the hot solvent method for the fabrication of anatase-phase TiO\({}_{2}\), utilizing TBOT as the titanium source, along with the sol-gel technique for the fabrication of FS-FT (0 g). The FS-FT (0.18-0.45 g) catalysts were obtained by controlling the amount of FeCl\({}_{3}\)-6H\({}_{2}\)O added.  
The photocatalytic removal of MO was performed using FS-FT catalysts (0-0.45 g) with different iron concentrations. The experimental results indicated that FS-FT (0.36 g) achieved a 99% degradation rate of MO, outperforming other catalysts under identical conditions. In contrast, the FS-FT (0 g) exhibited a degradation rate of 90.25%, suggesting that appropriate iron doping enhances the catalytic performance of FS-FT. The recycling experiment showed that FS-FT (0.36 g) had good recyclability. However, excessive iron doping can transition Fe from a capturing center to a complex center, increasing the recombination rate of photogenerated carriers, thereby inhibiting the photocatalytic degradation of acid dyes and resulting in a decreased degradation rate.  
Using a MO-Na\({}_{2}\)SO\({}_{4}\)-blended solution as a simulated pollutant, the experimental results demonstrated that FS-FT (0.36 g) effectively degraded methyl orange with a degradation rate of 97.16%, while the degradation rate of FS-FT (0 g) was slightly lower at 92.38%. The results demonstrate that FS-FT (0.36 g) still exhibits strong photocatalytic activity even in complex environments. The recycling experiment showed that FS-FT (0.36 g) had good recyclability. The degradation experiments of MO-Na\({}_{2}\)SO\({}_{4}\)-blended solutions with different concentrations using FS-FT (0.36 g) indicate that the inhibitory effect on FS-FT (0.36 g) becomes stronger as the Na\({}_{2}\)SO\({}_{4}\) concentration increases. The observed decrease in photocatalytic degradation efficiency with MO can be attributed to the introduction of a significant amount of sulfate ions (SO\({}_{4}\)\({}^{2-}\)) upon the addition of Na\({}_{2}\)SO\({}_{4}\). These sulfate ions  
Figure 12: Photodegradation principle of MO-Na\({}_{2}\)SO\({}_{4}\) using FS-FT (0.36 g).  
adsorbed onto the photocatalyst surface and combined with holes, acting as a pore-trapping agents to generate sulfate radicals (SO\({}_{4}\bullet^{-}\)). Fe\({}^{3+}\) ions reacted with free electrons to form Fe\({}^{2+}\), which is crucial in the photocatalytic degradation process. The reduction in the concentrations of Fe\({}^{3+}\) and free electrons adversely affected the photocatalytic performance, leading to decreased photoelectric conversion efficiency and a lower degradation rate, ultimately inhibiting the degradation of the MO-Na\({}_{2}\)SO\({}_{4}\)-blended solution.  
The results also indicated that the photocatalytic removal of MO using FS-FT (0 g) and FS-FT (0.36 g) followed first-order kinetic equations. The degradation rate of FS-FT (0.36 g) was found to be higher than that of FS-FT (0 g), suggesting that iron doping altered the lattice structure of TiO\({}_{2}\), enhancing its photocatalytic degradation rate.  
Conceptualization, L.S. and Z.Y.; methodology, L.S. and Z.L.; software, Z.L. and X.O.; validation, L.S., Z.Y., and Z.L.; formal analysis, L.S., Z.L., and X.O.; investigation, S.M. and Z.C.; resources, L.S. and Z.Y.; data curation, L.S., Z.L., and X.O.; writing--original draft preparation, L.S. and Z.L.; writing--review and editing, L.S. and Z.C.; visualization, Y.L. and K.Z.; supervision, L.S. and Y.L.; project administration, F.M. and Y.X.; funding acquisition, L.S. and S.M. All authors have read and agreed to the published version of the manuscript.  
This work has been subsidized by the National Natural Science Foundation of China (Grant No. 11904268) and Science and Technology Program of Hubei Province (CN) (Grant No. 2019 CFB613).  
The data are contained within this article.  
The authors declare no conflicts of interest.