Simultaneous removal of norfloxacin and chloramphenicol using cold atmospheric plasma jet (CAPJ): Enhanced performance, synergistic effect, plasma-activated water (PAW) contribution, mechanism and toxicity evaluation

Abstract

The extensive abuse and inadvertent discharge of various antibiotics into the environment has become a serious problem for posing a big threat to human health. In order to deal with this problem, we utilized cold atmospheric plasma jet (CAPJ) to treat two different antibiotics, namely, norfloxacin and chloramphenicol, and investigated the efficiencies and corresponding mechanisms for removing the mixed antibiotics. In the application of the CAPJ technique, we made use of not only the direct plasma processing, but also the indirect plasma-activated water (PAW) treatment. The efficiency for mixed antibiotics treatment was considerably enhanced as compared to the efficiency for treatment of single antibiotics. The contributions from the CAPJ-induced reactive oxygen/nitrogen species (RONS) were examined, showing that ·OH and 1O2 played a major role in the degradation of norfloxacin and chloramphenicol in the direct plasma treatment, while 1O2 played a major role in the PAW treatment. The bio-toxicity evaluation was also provided to verify the ecological safety of the CAPJ treatment. As such, this work has not only showed the effectiveness of CAPJ treatment of mixed antibiotics, but also elucidated the mechanisms for the enhanced treatment efficiency, which may provide a new solution for treatment of antibiotics in the environment.