Constructing a 3D interconnected "trap-zap" β-CDPs/Fe-g-C₃N₄ catalyst for efficient sulfamethoxazole degradation via...

A novel and high-efficiency catalyst Fe doped g-C₃N₄ (Fe-g-C₃N₄) composited with β-cyclodextrin polymers (β-CDPs) was synthesized for activating peroxymonosulfate (PMS). The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that the catalyst was 3D interconnected porous structure. The degradation rate constant of sulfamethoxazole (SMX) in β-CDPs/Fe-g-C₃N₄+PMS system was estimated to be 0.132 min^-1, which was 14.7 times and 2.2 times that of g-C₃N₄+PMS and Fe-g-C₃N₄+PMS system, respectively. In addition, the β-CDPs/Fe-g-C₃N₄ exhibited superior degradation performance in a wide pH range (3.0-9.0) and good selectivity in the presence of other inorganic anions and natural organics. Radical scavenging, electron paramagnetic resonance (EPR) and electrochemical measurements indicated that ¹O₂ and Fe(V)O were the main active species for SMX degradation in β-CDPs/Fe-g-C₃N₄+PMS system. Moreover, β-CDPs accelerated electron transfer between catalyst and PMS and promoted the generation of reactive oxygen species (ROS) during PMS activation. The loading of β-CDPs increased the yields of Fe(V)O and ¹O₂ in the system and limited the leaching of Fe³⁺. In addition, the possible degradation pathways of SMX were described based on the intermediates detected by liquid chromatography-mass spectrometry (LC-MS), and the toxicity of the intermediates was also evaluated. This work investigate the role of β-CDPs in PMS activation for the first time and develop a promising material with potential for water treatment.