New insights of metal free 2D graphitic carbon nitride for photocatalytic degradation of bisphenol A.

Polymeric oxygen rich exfoliated graphitic carbon nitride (exfoliated GCN, EGCN) was synthesized by the acid treatment of bulk GCN. The photocatalyst was characterized using X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and point of zero charge. EGCN shows high valance band hole transfer under short-time visible light (λ > 420 nm) exposure for photocatalytic mineralization of bisphenol A (BPA). Enhanced BPA removal was achieved by EGCN (99 %) due to formation of OH● radicals (H2O/hVB+ →OH●/H+). Major factors affecting BPA degradation including catalyst dose, wide pH range, and pollutant concentration were optimized. Repeated cycles of BPA degradation were performed with negligible rate decreased from 0.045 to 0.029 min-1. The degradation profile and plausible reaction mechanism of BPA was established and well justified by the byproducts identified by mass analysis HR-ESI-MS. Therefore, the as-synthesized metal free EGCN, active under visible light, offers a new platform for complete mineralization of byproducts of halogenated organic contaminants.