Multiaperture g-C₃N₄@SiO₂ to activate peroxydisulfate via visible light for efficient Rhodamine B removal

The sulfate radical-based advanced oxidation process (SR-AOPs) has been verified as a promising method to handle the persistent organic compounds in water using peroxydisulfate (PDS) as oxidant. A Fenton-like process was constructed and showed great potential to remove organic pollutants using visible-light-assisted PDS activation. The g-C₃N₄@SiO₂ was synthesized via thermo-polymerization, and characterized using powder X-ray diffraction (XRD), scanning electron microscope equipped with an energy-dispersive X-ray (SEM-EDX), X-ray photoelectron spectroscopy (XPS), N₂ adsorption-desorption, Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) method, photoluminescence (PL), transient photocurrent, and electrochemical impedance. Photocatalytic performance was demonstrated using the removal rate of Rhodamine B (RhB), and 96.08% RhB was removed from the solution within 50 min (10 mg/L in 200 mL, g-C₃N₄@SiO₂ = 0.25 g/L, pH = 6.3, PDS = 1 mmol/L). The free radical capture experiment proved that HO^•, h⁺, [Formula: see text] and [Formula: see text] were generated and removed RhB. The cyclic stability of g-C₃N₄@SiO₂ has also been studied, and the result shows no noticeable difference in the six cycles. The system of visible-light-assisted PDS activation might provide a novel strategy for wastewater treatment and must be an environment-friendly catalyst.