Crystallization regulation of Fe0@Fe3O4 using a g-C3N4/diatomite composite for enhancing photocatalytic peroxymonosulfate activation

Photocatalysis and persulfate synergistic catalysis have recently become promising technologies for degrading refractory organic contaminants in effluents. In this work, Fe0@Fe3O4 is successfully immobilized on a N-deficient g-C3N4/diatomite composite (NGD) via a simple self-assembly process. The structural characteristics and peroxymonosulfate activation ability of the composite under visible-light irradiation are explored in detail. Notably, the introduction of NGD affects the crystallinity and morphology of Fe0@Fe3O4, forming homogenously distributed nanoparticles rather than irregular and agglomerated crystals with rod-like structures. The synthesized Fe0@Fe3O4/N-deficient g-C3N4/diatomite composite (FNGD) exhibits a superior removal percentage of bisphenol A (> 95% within 15 min). Furthermore, its degradation rate constant (k) is ~59 and ~27 times higher than those of NGD and bare Fe0@Fe3O4, respectively. Moreover, holes (hvb+), singlet oxygen (1O2) and superoxide free radicals (•O2-) play a major role in the FNGD/peroxymonosulfate/visible system based on radial quenching experiments and electron paramagnetic resonance spectra. Overall, this study provides novel insights into visible light-assisted peroxymonosulfate activation by the g-C3N4/mineral-based composite for wastewater treatment.