A novel Z-Scheme photocatalyst (TCN) was prepared with TiO 2 and graphitic carbon nitride (GCN) and utilized to study the degradation efficiency of a binary dye mixture consisting of 5 ppm Rhodamine B (RhB) and 5 ppm Crystal Violet (CV) solutions by persulfate activation. Derivative spectrometric analysis was adopted to find the degradation efficiencies of the individual dyes in the mixture.The results indicate that in the presence of persulfate ions 0.6 TCN gives 100 % degradation in 60 min and 30 min for Rh B and CV, respectively. Hydroxyl radicals, superoxide radicals, and sulfate radicals were found to be the active species involved in photocatalytic degradation. From the results of radical scavenging experiments and band potentials of the semiconductors, a plausible mechanism of photocatalytic degradation of the model pollutants is proposed.

Recent advances in photocatalysis include the development of floating catalysts since they assure efficient and rapid recollection of the catalysts from the purified liquid, besides enhancing the availability of photons at the catalytic surface. Bismuth ferrite (BiFeO3 and BFO) is a multifunctional perovskite material renowned for its excellent photocatalytic properties. Since bandgap of BFO falls in the visible spectrum, BFO nanoparticles could be combined with a suitable floating substrate to develop efficient visible light photocatalysts. Here, we report the synthesis of BFO–polydimethylsiloxane (PDMS) hybrids for photocatalytic applications, where sol-gel–synthesized BFO nanoparticles are immobilized on a floating porous PDMS sponge. The successful incorporation of the nanoparticles on PDMS is confirmed using Raman spectroscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. The photocatalytic activity of the floating catalysts was studied by monitoring the degradation of malachite green dye under visible light irradiation. The effect of the amount of BFO immobilized, and the area and thickness of the PDMS sponge on the photocatalytic activity of the floating catalysts were investigated. An efficiency of 80.5% was obtained when the weight of BFO immobilized on the PDMS sponge was 5 mg. The method yields degradation efficiencies comparable with or higher than that of conventional BFO powder catalysts, even with 6–18 times less catalyst loading. The method introduces the fabrication of recyclable floating photocatalysts of notable efficiency using significantly less amount of BFO nanoparticles, which could be further modified by approaches such as doping, functionalization, or composite formation.