One-step synthesis of magnetic-TiO2-nanocomposites with high iron oxide-composing ratio for photocatalysis of rhodamine 6G

Figure 1. XRD patterns of MNPs and magnetic-TiO2-nanocomposites.Figure 2. Characteristics of magnetic-TiO2-nanocomposites. Including XPS spectra of the synthesized MNPs and magnetic-TiO2-nanocomposites (A), Fe2p region spectra (MNPs (B), FexOy/TiO2-0.5 (C), FexOy/TiO2-0.35 (D), FexOy@TiO2-0.5 (E) and FexOy@TiO2-0.35 (F)) and magnetization curve for magnetic-TiO2-nanocomposites (G).Figure 3. Langmuir (dotted line) and Freundlich (solid line) adsorption isotherms of R6G on the synthesized magnetic-TiO2-nanocomposites, ((A) for FexOy/TiO2-0.5, (B) for FexOy/TiO2-0.35, (C) for FexOy@TiO2-0.5 and (D) for FexOy@TiO2-0.35.) spots represent experimental data. Figure 4. Impacts of pH on R6G photocatalysis performance. (A) pH=3, (B) pH=7, (C) pH=10. Dotted lines represent photolysis of R6G under UV-irradiation without magnetic-TiO2-nanocomposites, solid lines represent removal rate of R6G under UV-irradiation with magnetic-TiO2-nanocomposites. Experimental conditions: UV-irradiation, 253 nm (20 W); magnetic-TiO2-nanocomposites concentration, 0.4 g/L; initial R6G concentration, 10 mg/L. Figure 5. Impacts of magnetic-TiO2-nanocomposite concentration on R6G degradation kinetics. (A) FexOy/TiO2-0.5, (B) FexOy/TiO2-0.35, (C) FexOy@TiO2-0.5 and (D) FexOy@TiO2-0.35. Experimental conditions: UV-irradiation, 253 nm (20 W); initial R6G concentration, 10 mg/L; initial magnetic-TiO2-nanocomposites concentration, 0.2 mg/L, 0.4 mg/L and 0.8 mg/L, respectively; pH, 7.0.Figure 6. R6G degradation performance after reusing magnetic-TiO2-nanocomposites 5 times. Dotted lines represent blank R6G without magnetic-TiO2-nanocomposites, solid lines represent removal rate of R6G under UV-irradiation with magnetic-TiO2-nanocomposites. Experimental conditions: UV-irradiation, 253 nm (20 W); initial magnetic TiO2 nanocomposites concentration, 0.4 g/L; initial R6G concentration, 10 mg/L; pH, 7.0.Figure S3. Energy dispersive spectroscopy pattern of synthesized magnetic-TiO2-nanocomposites. (A) FexOy/TiO2-0.5, (B) FexOy/TiO2-0.35 (C) FexOy@TiO2-0.5 and (D) [e-mail] S4. R6G adsorption kinetics on the synthesized magnetic-TiO2-nanocomposites. (A) 1 mg/L, (B) 5 mg/L, (C) 10 mg/L, (D) 15 mg/L, (E) 20 mg/L, (F) 25 mg/L. Experimental conditions: magnetic-TiO2-nanocomposites concentration, 0.4 g/L; pH, 7.0.Figure S5. Impacts of pH on R6G adsorption on the synthesized magnetic-TiO2-nanocomposites. Experimental conditions: magnetic-TiO2-nanocomposites concentration, 0.4 g/L; initial R6G concentration, 10 mg/L.Figure S6. R6G declining curves of the synthesized magnetic-TiO2-nanocomposites without UV-irradiation. (A) pH=3.0, (B) pH=7.0, (C) pH=10.0.Figure S7. Impacts of irradiation wavelength on the R6G photocatalytic degradation of the synthesized magnetic-TiO2-nanocomposites. (A) 460 nm, (B) 540 nm.Figure S8. Percentage of R6G loss during the photocatalysis process. The number in x-axis (0.2, 0.4 and 0.8) refers to the concentration of the synthesized magnetic-TiO2-nanocomposites (mg/L).Figure S9. Effects of magnetic-TiO2-nanocomposite concentration on R6G photodegradation kinetics. (A) FexOy/TiO2-0.5, (B) FexOy/TiO2-0.35, (C) FexOy@TiO2-0.5 and (D) FexOy@TiO2-0.35.

图1 为磁性纳米颗粒（MNPs）与磁性-TiO₂纳米复合材料的X射线衍射（XRD）图谱。
图2 为磁性-TiO₂纳米复合材料的表征结果，包含合成的MNPs与磁性-TiO₂纳米复合材料的X射线光电子能谱（XPS）总谱（A）、Fe 2p高分辨谱（分别对应MNPs（B）、FexOy/TiO2-0.5（C）、FexOy/TiO2-0.35（D）、FexOy@TiO2-0.5（E）以及FexOy@TiO2-0.35（F）），以及磁性-TiO₂纳米复合材料的磁化曲线（G）。
图3 为合成的磁性-TiO₂纳米复合材料对罗丹明6G（R6G）的朗缪尔（Langmuir）与弗伦德里希（Freundlich）吸附等温线，其中虚线对应朗缪尔模型、实线对应弗伦德里希模型；(A)对应FexOy/TiO2-0.5、(B)对应FexOy/TiO2-0.35、(C)对应FexOy@TiO2-0.5、(D)对应FexOy@TiO2-0.35，图中散点代表实验实测数据。
图4 为pH值对R6G光催化性能的影响，其中(A)为pH=3、(B)为pH=7、(C)为pH=10。虚线代表无磁性-TiO₂纳米复合材料时，紫外照射下R6G的光解过程；实线代表添加磁性-TiO₂纳米复合材料后，紫外照射下R6G的去除率。实验条件：紫外照射波长253 nm（功率20 W）；磁性-TiO₂纳米复合材料投加浓度0.4 g/L；初始R6G浓度10 mg/L。
图5 为磁性-TiO₂纳米复合材料投加浓度对R6G降解动力学的影响，其中(A)对应FexOy/TiO2-0.5、(B)对应FexOy/TiO2-0.35、(C)对应FexOy@TiO2-0.5、(D)对应FexOy@TiO2-0.35。实验条件：紫外照射波长253 nm（功率20 W）；初始R6G浓度10 mg/L；磁性-TiO₂纳米复合材料初始投加浓度分别为0.2 mg/L、0.4 mg/L与0.8 mg/L；pH值为7.0。
图6 为磁性-TiO₂纳米复合材料重复使用5次后的R6G降解性能。虚线代表无磁性-TiO₂纳米复合材料的空白R6G体系；实线代表添加磁性-TiO₂纳米复合材料后，紫外照射下R6G的去除率。实验条件：紫外照射波长253 nm（功率20 W）；磁性-TiO₂纳米复合材料初始投加浓度0.4 g/L；初始R6G浓度10 mg/L；pH值为7.0。
图S3 为合成的磁性-TiO₂纳米复合材料的能量色散X射线能谱（EDS）图谱，其中(A)对应FexOy/TiO2-0.5、(B)对应FexOy/TiO2-0.35、(C)对应FexOy@TiO2-0.5、(D)对应FexOy@TiO2-0.35。
图S4 为合成的磁性-TiO₂纳米复合材料对R6G的吸附动力学曲线，其中(A)对应1 mg/L、(B)对应5 mg/L、(C)对应10 mg/L、(D)对应15 mg/L、(E)对应20 mg/L、(F)对应25 mg/L。实验条件：磁性-TiO₂纳米复合材料投加浓度0.4 g/L；pH值为7.0。
图S5 为pH值对合成的磁性-TiO₂纳米复合材料吸附R6G的影响。实验条件：磁性-TiO₂纳米复合材料投加浓度0.4 g/L；初始R6G浓度10 mg/L。
图S6 为无紫外照射时，合成的磁性-TiO₂纳米复合材料对R6G的消减曲线，其中(A)对应pH=3.0、(B)对应pH=7.0、(C)对应pH=10.0。
图S7 为照射波长对合成的磁性-TiO₂纳米复合材料光催化降解R6G的影响，其中(A)对应460 nm、(B)对应540 nm。
图S8 为光催化过程中R6G的损失率占比，横轴数值（0.2、0.4与0.8）代表合成的磁性-TiO₂纳米复合材料的投加浓度（单位：mg/L）。
图S9 为磁性-TiO₂纳米复合材料投加浓度对R6G光降解动力学的影响，其中(A)对应FexOy/TiO2-0.5、(B)对应FexOy/TiO2-0.35、(C)对应FexOy@TiO2-0.5、(D)对应FexOy@TiO2-0.35。