Engineering a FeOOH/g-C3N4/CA composite photocatalytic membrane for enhanced water treatment: synergistic photocatalysis and Fenton-like processes

Integrating membrane filtration, photocatalysis, and Fenton-like processes into a synergistic photocatalytic membrane has emerged as a highly promising strategy for efficient water treatment. Herein, a FeOOH/g-C₃N₄/CA composite membrane (FGCM) was designed and fabricated to combine membrane filtration with photocatalysis. Owing to the rational design, the FGCM achieved efficient separation of photo-generated charges and responded effectively to both visible light and actual solar light. The catalytic performance of the FGCM for rhodamine B (RhB) removal was systematically investigated under visible light with H₂O₂ assistance. The results showed a 93.2% removal within 2.72 ms residence time under optimized conditions. Experimental and mechanistic analysis demonstrated that the rational design of the FeOOH/g-C₃N₄ heterojunction broadened the visible-light absorption range and enhanced charge separation. Scavenging experiments and electron paramagnetic resonance (EPR) detection proved that ·OH, O₂˙⁻/¹O₂, and h⁺ played important roles in RhB removal. The ·OH and O₂˙⁻ radicals, produced from charge separation in g-C₃N₄, served as the dominant species for RhB degradation, while the promoted electron transfer from g-C₃N₄ to FeOOH drove the Fe(iii)/Fe(ii) cycle to continuously activate H₂O₂. Furthermore, the FGCM system demonstrated good anti-fouling ability, stability, and adaptability in complex water matrices.