Enhanced degradation of carbamazepine by electrochemical activation of peroxymonosulfate with PTFE/black carbon as cathode

Abstract

Sulfate radical (SO4•−)-based advanced oxidation processes (AOPs), such as the electro-activated peroxymonosulfate (E-PMS) process, have shown great potential for environmental remediation. As oxygen competes with PMS for electrons at the cathode in the E-PMS process, oxygen was proposed to be one of the negative factors reducing the generation of SO4•− in previous studies. Surprisingly, our preliminary experiment found that polytetrafluoroethylene-black carbon (PBC), which could efficiently produce H2O2 in the E-PMS process as a cathode, could produce an 18.4 times greater steady-state concentration of SO4•− than Pt cathodes with nearly no production of H2O2. In addition, the generation of SO4•− in the E-PMS process with a Pt cathode can also be significantly enhanced by dosing H2O2 in the system. Quenching experiments and electron paramagnetic resonance (EPR) analysis demonstrated that H2O2 could react with PMS at the cathode to produce superoxide radicals (O2•−). Furthermore, O2•− reacted with PMS in solution to generate SO4•−. In addition, the influence of various water matrices on carbamazepine (CBZ) removal was also discussed. Finally, the degradation pathways of CBZ were proposed and corresponding toxicity of products was analyzed by ecological structure activity relationships (ECOSAR) analysis. This study may present novel and fundamental insights into the E-PMS process and a simple and convenient approach to regulate the generation of SO4•− during PMS activation.