Nitrogen-doped carbon nanotubes encapsulating Fe/Zn nanoparticles as persulfate activator for sulfamethoxazole degradation: role of encapsulated bimetallic nanoparticles and nonradical reaction
In this work, the carbon nanotubes (CNTs) encapsulating Zn and Fe bimetallic nanoparticles (FeZn@NC) was synthesized through one-pot pyrolytic strategy. The persulfate (PS) activation ability of FeZn@NC with various ratios of Fe and Zn was determined by sulfamethoxazole (SMX) degradation. Result indicated that the iron played a key role to form external CNTs and the catalytic activity of FeZn@NC was mainly based on the encapsulated FeZn nanoparticles. In addition, PS activation was greatly strengthened by the hetostructure of FeZn@NC. Free radical quenching experiments and electron paramagnetic resonance (EPR) spectra suggested that the singlet oxygen was the key reactive oxygen species for SMX degradation. The activity of pyridinc-N, pyrrolic-N and graphitic-N on external CNTs was analyzed by the theoretical calculations, which showed the pyridinc-N processed strong adsorptive ability to active PS to sulfate radicals.