Designing of a magnetically recoverable (Ce^{+3, +4}/Fe⁺². Fe⁺³) _oxide@ 2D g-C₃N₄ surface for enhanced photo-Fenton catalytic degradation of Bismarck-Brown R and Congo red dyes: kinetics, optical properties,and mechanistic pathway studies

ABSTRACT

Co-precipitation-assisted hydrothermal synthesis was employed to synthesize Fe₃O₄/CeO₂ nanohybrids over 2D g-C₃N₄ (CF@GCN) for photo-Fenton catalytic degradation of Bismarck brown R (BBR) and Congo Red (CR) dyes. Initially, Fe loading was deployed in CF@GCN with different sets of molar ratios of Fe against the 1 mole of Ce (Ce: Fe=1:0.2-1). Among different sets, the one with 0.8 moles of Fe against the 1 mole of Ce (C₁F_0.8@GCN) performed excellently for BBR and CR dye degradation via aiding in the photo-Fenton process. Morphological, structural, compositional, and electronic states of the final nanocomposite were evaluated using powder X-ray diffraction, transmission electron microscopy/high-resolution transmission electron microscopy, selected area electron diffraction, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. BET analysis of the final nanocomposite showed an excellent surface area of 56.76 m²g⁻¹, allowing for effective degradation. UV–vis spectrophotometry, UV-DRS, and PL (photoluminescence) techniques were performed to monitor the optical properties of the final nanocomposite. Taulc’s plots estimated the band gaps of catalysts, and the final nanocomposite’s band gap was 2.2 eV, which was key for capturing photons from the light source and functioning the degradation process. Further, operating parameters such as catalyst dose, dye concertation, pH, H₂O₂ dose, and contact time studies were done with the final nanocomposite. C1F0.8@GCN degraded BBR up to 94.5 % within 30 minutes with a first-order rate constant of 0.09747 min⁻¹ and CR dye up to 97.7 % within 45 minutes with a first-order rate constant of 0.07391 min⁻¹. All results supported a nanocomposite of Fe₃O₄ nanoparticles and CeO₂ nanorods grown over 2D g-C₃N₄ sheets. As predicted, composing Fe₃O₄ sped up catalyst recovery. Also, the final nanocomposite’s dye degradation rate was consistent till the 6th run. So, the study proposes a cost-effective plan for dealing with organic water contaminants like hazardous dyes.

KEYWORDS:

• Staggered type II heterojunction
• photo-Fenton photocatalysis
• Congo red dye
• Bismarck brown dye
• magnetically recoverable photocatalyst

Disclosure statement

No potential conflict of interest was reported by the author(s).