Effective degradation of norfloxacin by 3D diatomite plate@polydopamine@WC co-catalytic Fenton at near-neutral pH

To further rush the reduction of Fe3+ and realize the simple application of cocatalyst, 3D diatomite plate@polydopamine@WC (DPW) cocatalysts were prepared using a simple two-step impregnation method to construct a DPW/Fenton system for degrading norfloxacin (NOR) at near-neutral pH (5.5). Characterization results from Scanning electron microscope (SEM), automatic mercury porosimeter, Brunauer-Emmett-Teller (BET) analyzer, and X-ray Photoelectron Spectroscopy (XPS) revealed that 3D DPW possessed a macroporous structure with W0 and W4+ distributed on its surface and within its pores. Under suitable conditions, the DPW/Fenton could degrade 94.98 % of NOR with a reaction rate constant of 0.2087 min−1, being 2.08 and 1.09 times that of MoS2/Fenton and WS2/Fenton, respectively. The Fe2+ content in DPW/Fenton was 1.13 and 1.05 times that of MoS2/Fenton and WS2/Fenton at 15 min. The exposed W0/W4+ sites on DPW enhanced the Fe3+/Fe2+ cycle and increased the H2O2 decomposition rate to 39.82 %. EPR measurements and probe experiments indicated that NOR degradation occurred mainly through·OH-dominated radical pathway. Notably, DPW/Fenton had strong resistance to inorganic salt ions and humic acid, maintaining high degradation rates (68 %, 75 %, and 78 %) for high-ionization-potential contaminants (IP ≥ 9.1 eV) like benzoic acid, terephthalic acid and p-nitrophenol. Impressively, the activity of DPW could be regenerated by the impregnation procedure. Even after 24 reuses, the degradation efficiency of NOR was still above 80 %, and the dissolved concentration of W was below 0.022 mg/L. Interestingly, after being stored for 5 months, the catalytic activity of DPW remained basically unchanged. This work provides a theoretical basis and technical support for the large-scale preparation and convenient application of DPW, as well as the degradation of toxic organic contaminants.