1：Experimental Design and Method Selection:

The study involved synthesizing Fe-TiO2 nanoparticles via a hydrothermal sol-gel method with variations in Fe content (0, 0.3, 0.6, 1.0 at.%), characterizing them using XRD, BET, TEM, SEM, DRS, and XPS, and evaluating photocatalytic activity through hydroxyl radical generation using pNDA probe and E3 degradation under high and low UV irradiation sources (GE F15T8 BLB and GE F15T8 D lamps).

2：3, 6, 0 at.%), characterizing them using XRD, BET, TEM, SEM, DRS, and XPS, and evaluating photocatalytic activity through hydroxyl radical generation using pNDA probe and E3 degradation under high and low UV irradiation sources (GE F15T8 BLB and GE F15T8 D lamps). Sample Selection and Data Sources:

2. Sample Selection and Data Sources: Samples included zero-iron TiO2, Fe-TiO2 with different Fe concentrations, and commercial Aeroxide? TiO2 P25. Data were obtained from laboratory experiments with controlled conditions (pH 6 ± 0.1, 20°C).

3：Data were obtained from laboratory experiments with controlled conditions (pH 6 ± 1, 20°C). List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: Equipment included XPS spectrometer (Thermo Fisher Scientific K-Alpha), UV-visible spectrophotometer (Hatch DR/4000U), HPLC system (Waters 1515), SEM (JEOL JSM-7800 F), TEM (JEM-2100 LaB6), BET analyzer (Nova Station A), XRD diffractometer (Siemens D-5000), photoreactor with GE lamps, thermostatic bath (Polystat), centrifuge (Biofuge Primo), and muffle furnace (Isotemp?). Materials included estriol, titanium isopropoxide, pNDA, SDS, iron(III) nitrate, HNO3, ethanol, methanol, and deionized water from Sigma-Aldrich and other suppliers.

4：Experimental Procedures and Operational Workflow:

Synthesis involved dissolving precursors, adjusting pH, thermal treatment, and washing. Photocatalytic tests involved preparing solutions, adding catalyst, dark phase for adsorption, irradiation, sampling, centrifugation/filtration, and analysis via UV-vis spectrophotometry for pNDA and HPLC for E

5：Data Analysis Methods:

Data were analyzed using pseudo-first-order kinetics for degradation rates, linear regression for correlations, and empirical modeling for Fe content effects. Software included Excel Solver for numerical approximations and XPSpeak for spectral deconvolution.