Systematical comparison of antibiotic degradation in the activated peroxymonocarbonate and Fenton systems: Kinetics, matrix influence, mechanisms and intermediate toxicities

Abstract

The degradation of representative antibiotics and their mechanisms in the activated peroxymonocarbonate (PMC) and Fenton systems were systematically investigated and compared in this work. The PMC can exist and be reliable at high ratios for 1 h according to the 13C nuclear magnetic resonance spectra. The activated PMC system was proven to be more efficient than the Fenton system for the degradation of sulfamethoxazole, ciprofloxacin and ceftriaxone under same experiment conditions. The activated PMC system exhibited higher sulfamethoxazole removal performance in different actual water matrices due to the insignificant effect of coexisting substances, while the impurities had an adverse impact on the Fenton system. The pH of the activated PMC system was relatively stable and ranged from 7.8 to 8.2, while the pH of the Fenton system dropped from 5.2 to 4.1. The slight decreases of sulfamethoxazole removal efficiencies were observed after bubbling O2, N2 and CO2 in the Fenton system, while removal rates in the activated PMC system were greatly prohibited and the inhibition ratios increased with gas solubility. The selective 1O2 and CO3− played primary roles in the activated PMC system according to scavenging experiments and time-series spin-trapping electron spin resonance spectra, which resulted in higher removal efficiencies and lower oxidation degree. The non-selective OH contribution was dominant in the Fenton system. The activated PMC system was more suitable for subsequent biological treatment and friendlier to the ecosystem than the Fenton system according to intermediate pharmacophore removal and toxicity comparisons. The activated PMC system showed apparent advantages over the Fenton system in most cases, which might encourage more researchers to devote their interest and time on this promising degradation system.