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→·O2−→1O2. This work provides new inspiration into the mechanisms of antibiotic degradation and electron transfer based on PMS activation.