Highly efficient chloramphenicol degradation by UV and UV/H2 O2 processes based on LED light source.

Abstract

In this study, UV-LED was employed as a novel light source to investigate the degradation of a representative antibiotic compound, chloramphenicol (CAP), in the absence or presence of H2 O2 . The UV-LED irradiation showed a higher capability for degradation of CAP than conventional UV-Hg vapor lamps. Effects of the initial CAP concentration, UV wavelength, and light intensity on the degradation of CAP by UV-LED were evaluated. Introduction of H2 O2 evidently enhanced the degradation efficiency of CAP due to the production of reactive hydroxyl radicals. Results showed that the UV-LED/H2 O2 removed CAP by up to 95% within 60min at pH 5.0, which was twice as that achieved by the UV-LED alone. The degradation products were identified to propose plausible degradation pathways. Moreover, the formation potentials of typical carbonaceous disinfection by-products (C-DBPs) and nitrogenous disinfection by-products (N-DBPs) were assessed for the CAP polluted water treated by the UV-LED alone and UV-LED/H2 O2 processes. Results indicate unintended formation of certain DBPs, thereby highlighting the importance of health risk assessments before practical application. This study opens a new avenue for developing environment-friendly and high-performance UV-LED photocatalytic reactors for abatement of CAP pollution in water. PRACTITIONER POINTS: UV-LED bore higher capability to degrade CAP than low-pressure Hg lamp. The optimal performance to degrade CAP can be achieved at the UV wavelength of 280nm. The degradation efficiency under UV-LED/H2 O2 process was double of that under UV-LED process. TCM, DCAN, and TCNM formation were higher under the existence of UV-LED radiation. The addition of H2 O2 had greater influence on the formation of DCAcAm than the introduction of UV-LED.