2.3. Photocatalytic Tests and Analytical Methods

The photocatalytic experiments were conducted in a photochemical reaction instrument (BL-GHX-CH500, Xi’an Depai Biotech. Co. Ltd., Xi’an, China) and a 500 W xenon lamp was applied as the visible-light source. Typically, 40 mg FePcS–PMA–LDH was added to 100 mL of BPA solution with the initial concentration of 10 mg L⁻¹. The initial pH value of the solution was adjusted by adding NaOH or HNO₃ solutions. The mixed solution was magnetically stirred for 30 min in the dark to achieve adsorption equilibrium between FePcS–PMA–LDH and BPA. Then, the xenon lamp was turned on and H₂O₂ was added to the BPA solution. At predetermined time intervals, the sample was taken out and centrifuged to obtain the supernatant for analysis. The concentration of the remaining BPA in the aqueous solution was determined with high efficiency liquid chromatography (HPLC, Agilent 1260). The concentration of Total Organic Carbon (TOC) during the degradation solutions was measured by a TOC analyzer (Shimadzu TOC-L CPH CN 200, Kyoto, Japan) equipped with an auto-sampler. Electron spin resonance (ESR) spectra of •OH, O₂^•−, and ¹O₂ were tested by an ESR spectrometer (JEOL JES-FA, Peabody, MA, USA).