Degradation of Sulfamethoxazole Using Peroxymonosulfate Activated by Self-Sacrificed Synthesized CoAl-LDH@CoFe-PBA Nanosheet: Reactive Oxygen Species Generation Routes at Acidic and Alkaline Ph

Novel cobalt aluminum layered double hydroxide@cobalt aluminum Prussian blue analogs (CoAl-LDH@CoFePBA) nanosheet was synthesized via a self-sacrificed method from CoAl-LDH. The morphology and physicochemical properties characterization showed that CoAl-LDH@CoFe-PBA nanosheets were hexagon shape with diameter of 100 nm. Peroxymonosulfate (PMS) activation via CoAl-LDH@CoFe-PBA towards sulfamethoxazole (SMX) degradation was systematically examined. The catalytic system showed a satisfactory SMX degradation efficiency (over 80%) with the initial pH range of 3.0-9.0. In particular, only similar to 8 min was required to achieve 98% of SMX (40 mu M) degradation with 0.1 g/L CoAl-LDH@CoFe-PBA and 0.3 mM PMS. Besides, the underlying reaction mechanism and generation routes of various reactive oxygen species (ROS) with varied initial pH was explicated by the electron paramagnetic resonance (EPR) and quenching tests. The surface-bound (OH)-O-center dot and O-1(2) were responsible for SMX degradation at acidic pH, and O-1(2) was mainly produced from O-2(center dot-). At alkaline pH, SO4 center dot- and O-1(2) co-contributed to the degradation, while O-1(2) was generated from O-2(center dot-) and SO4 center dot-. Oxygen vacancy in the inner space of the catalyst was considered as key electron donors involved in O-2(center dot-) production. In addition, nine major degradation intermediates of SMX were identified and the possible degradation pathways were further proposed accordingly.