Rapid peroxymonosulfate activation by self-assembly of layered fluorine-free MXene with nanofibrous Co3O4: Antibiotic degradation and electron transfer mechanism

Herein, nanofibrous Co3O4 was self-assembled with lamellar fluorine-free MXene (Ff-Ti3C2Tx) to prepare a nanofibrous layered structure of Ff-Ti3C2Tx-Co3O4. Benefiting from the unique structure, Ff-Ti3C2Tx-Co3O4 exhibited excellent catalytic activity for degradation (nearly 100%) in the pH range of 4-10 and was resistant to ionic interference. The Ff-Ti3C2Tx-Co3O4 membranes were prepared by vacuum filtration, permeated 220 mL of sulfamethoxazole (SMX) in the municipal wastewater influent matrix and maintained removal efficiency above 95%. Furthermore, PMS decomposition was linearly correlated with SMX degradation and each millimolar of PMS oxidized 0.425 mM of SMX. Meanwhile, electrons were rapidly transferred from Ff-Ti3C2Tx-Co3O4 to PMS to consume HCO5  and produce metastable active species (Ff-Ti3C2Tx-Co3O4-PMS*). The mechanism of rapid SMX degradation involved fast electron transfer in Ti2+/Ti3+⇋Ti4+ and Co2+⇋Co3+ redox cycles with PMS. Furthermore, 1O2 was generated via PMS ->center dot O2  -> 1O2. This work provides new inspiration into the mechanisms of antibiotic degradation and electron transfer based on PMS activation.

Automated summary

In this study, a nanofibrous layered structure of Ff-Ti3C2Tx-Co3O4 was prepared by self-assembling nanofibrous Co3O4 with lamellar fluorine-free MXene (Ff-Ti3C2Tx). The Ff-Ti3C2Tx-Co3O4 exhibited excellent catalytic activity for degradation, resistant to ionic interference, and maintained high removal efficiency of sulfamethoxazole (SMX) in municipal wastewater. The rapid SMX degradation involved fast electron transfer in redox cycles with PMS and the generation of 1O2 via PMS ->center dot O2  -> 1O2. This work provides new insights into antibiotic degradation mechanisms and electron transfer based on PMS activation.