1：Experimental Design and Method Selection:

The study involved synthesizing sodium-doped g-C3N4 (Na-g-C3N4) by calcination and doping with NaCl, followed by characterization and photocatalytic testing under solar light. The Langmuir-Hinshelwood model was used for kinetic analysis.

2：Sample Selection and Data Sources:

Real tannery effluent was collected and characterized; phenol was extracted using isobutyl acetate. Synthetic catalysts (g-C3N4 and Na-g-C3N4 with varying NaCl amounts) were prepared.

3：List of Experimental Equipment and Materials:

Equipment included XRD diffractometer, FTIR spectrometer, UV-vis spectrophotometer, PL spectrometer, FESEM, TEM, gas sorption analyzer, TGA, zeta potential analyzer, XPS, ICP-AES, GC-MS, pH meter, conductivity meter, and solar photocatalytic reactor. Materials included melamine, NaCl, ethanol, isobutyl acetate, H2O2, and deionized water.

4：Experimental Procedures and Operational Workflow:

Synthesis involved calcination of melamine to form g-C3N4, grinding with NaCl, dissolution in ethanol-water, drying, and calcination. Characterization included structural, optical, and morphological analyses. Photocatalytic experiments were conducted in a solar reactor with varied parameters (irradiance time, pH, H2O2 concentration, flow rate), and phenol degradation was monitored.

5：Data Analysis Methods:

Data were analyzed using standardized illumination time, percentage reduction calculations, and kinetic modeling with the Langmuir-Hinshelwood equation. Statistical means of triplicate experiments with error bars were reported.