1：Experimental Design and Method Selection:

The study employed g-C3N4 as a photocatalyst for reduction and oxidation reactions. Catalytic reduction of Cr(VI) used formic acid (FA) as a reducing agent, and oxidative degradation of SIZ used potassium peroxydisulfate (PS) as an oxidizing agent under visible light irradiation. Mechanisms were investigated using electron spin resonance (ESR) spectroscopy.

2：Sample Selection and Data Sources:

g-C3N4 was synthesized via urea pyrolysis. Cr(VI) source was potassium dichromate, and SIZ was purchased. De-ionized water was used for all experiments.

3：List of Experimental Equipment and Materials:

Equipment included SEM (Hitachi S-4800), TEM (JEM-2100 F), XRD (Shimadzu XRD-6000), XPS (ESCALAB 250), FTIR (Nicolet 670), UV-vis spectrophotometer (Cary 50 Scan, UV-2450), HPLC (Agilent 1200 infinity series), ESR spectrometer (JES-FA200), Zetasizer nano ZS90. Materials included urea, formic acid, potassium peroxydisulfate, sulfisoxazole, and various chemicals from Sinopharm and other suppliers.

4：Materials included urea, formic acid, potassium peroxydisulfate, sulfisoxazole, and various chemicals from Sinopharm and other suppliers. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: For Cr(VI) reduction, g-C3N4 was dispersed in water with Cr(VI) and FA, stirred for adsorption equilibrium, then irradiated with visible light. Samples were taken at intervals, filtered, and Cr(VI) concentration measured by UV-vis. For SIZ degradation, similar steps with PS added, and SIZ concentration measured by HPLC. pH was adjusted using NaOH and HCl.

5：Data Analysis Methods:

Kinetics analyzed using ln(C/C0) = kt. ESR used to identify radicals. XPS and other techniques for material characterization.