Elimination of aqueous levetiracetam by a cyclic flow-through electro-peroxone process

Abstract

Emerging contaminant levetiracetam (LEV) poses potential threats to natural ecosystems and human health. In this work, a cyclic flow-through electro-peroxone (E-peroxone) process was investigated for aqueous LEV removal. Results showed that E-peroxone oxidation exhibited much more efficient in target pollutant degradation than individual processes. The LEV removal ratio at 15 min E-peroxone treatment was ~53.4%, while only ~22.1% and ~7.9% were obtained in ozonation and electrolysis processes, respectively. Moreover, the response surface methodology (RSM) analysis indicated that the appropriate increase in inlet ozone concentration, applied current, solution initial pH and cyclic flow rate significantly enhanced the LEV removal, while complex interaction effects between various operational parameters was observed. Furthermore, the comparison tests revealed that the decomposition of ozone and H2O2 could be accelerated in the combined E-peroxone system, which resulted in the synergistic formation of HO, thereby promoting the treatment efficiency. The linear sweep voltammetry (LSV) determination conjoined with the ozone mass transfer analysis implied that the cathodic ozone reduction and the enhanced reactants mass transfer also contributed to the reactive oxygen species (ROS) production. These observations suggest that cyclic flow-through operation has the potential for improvement of E-peroxone treatment, and this technique could be used for aqueous LEV removal.